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Accepted papers to appear in an upcoming issue

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Generalized sequential four-step phase-shifting color digital holography

Takanori Nomura and Kazuma Shinomura

Doc ID: 296886 Received 30 May 2017; Accepted 25 Jul 2017; Posted 25 Jul 2017  View: PDF

Abstract: A generalized sequential four-step phase-shifting color digital holography using a color camera is proposed. As an arbitrary phase-shift quantity can be used for four-step phase-shifting, three primary color phase-shifting digital holograms can be recorded simultaneously. Experimental results for transparent and reflective objects are shown to confirm the proposed phase-shifting digital holography.

Progress in high power continuous wave quantum cascade lasers

Pedro Figuieredo, Matthew Suttinger, Rowel Go, Eugene Tsvid, Chandra Kumar Patel, and Arkadiy Lyakh

Doc ID: 297486 Received 05 Jun 2017; Accepted 24 Jul 2017; Posted 25 Jul 2017  View: PDF

Abstract: Multi-watt continuous wave room temperature operation with efficiency exceeding 10% has been demonstrated for quantum cascade lasers in the entire mid-wave and long-wave infrared spectral regions. These devices are the only room temperature lasers that directly convert electrical power into infrared optical power. In this manuscript, we review the progress in high power quantum cascade lasers made over the last ten years. Specifically, an overview of the most important active region, waveguide, and thermal design techniques is presented and various aspects of die packaging for high power applications are discussed. Prospects of power scaling with lateral device dimensions for reaching optical power level in the range from 10W to 20W are also analyzed. Finally, coherent and spectral beam combining techniques for very high power infrared platforms are discussed.

Superconductor based ternary periodic multilayered structure as a single and multichanneled filter in the terahertz region

NIRMALA MARIA D SOUZA and Vincent Mathew

Doc ID: 293331 Received 24 Apr 2017; Accepted 24 Jul 2017; Posted 25 Jul 2017  View: PDF

Abstract: A single as well as a multichannelled filter in the terahertz (THz) region have been proposed by desiging a one dimenstional photonic crystal(PhC) structure using a High Temperature Superconductor (HTS)-air-dielectric ternary periodic structure. The filter is designed withoutincorporating any defect, which is rarely been proposed in a ternary PhC structure. The theoretical study of transmittancewas performed by applying transfer matrix method. The transition from single channel to desired multichannel is achieved by adjusting the number of periods. Furthermore, the impact of the thicknesses and dielectric constants of the constituting layers was investigated. In addition to this, the tunability is achieved by the influence of temperature-dependent dielectric constant of the superconductor.

Bounds of Parameter Estimation for Interference Signals

Chengshuai Li and Yizheng Zhu

Doc ID: 295091 Received 02 May 2017; Accepted 24 Jul 2017; Posted 25 Jul 2017  View: PDF

Abstract: Parameter estimation, especially frequency estimation, from noisy observations of interference is essential inoptical interferometric sensing and metrology. The Cramer-Rao bound of such estimation determinesmeasurement sensitivity limit. Unlike the well-studied complex sinusoids in communication theory, opticalinterference signal is distinctly different in its model parameters and noise statistics. The connection betweenthese parameters and their estimation bounds has not been well understood. Here we propose a complete, realisticmulti-parameter interference model corrupted by a combination of shot noise, dark noise and readout noise. Wederive the Fisher information matrix and the Cramer-Rao bounds for all model parameters, including intensity,visibility, optical path length (frequency) and initial phase. We show that the Cramer-Rao bounds of frequency andphase are coupled but not affected by the knowledge of intensity and visibility. Knowing the initial phase offerssignificant sensitivity advantage, which is verified by both theoretical derivations and numerical simulations. Inaddition to the complete model, a shot noise-limited case is studied, which permits the calculation of theCramer-Rao bounds directly from measured data.

Pattern-illuminated Fourier ptychography microscopywith a pattern-estimation algorithm

Ruizhi Cao, Tingting Yang, Yue Fang, Cuifang Kuang, and Xu Liu

Doc ID: 293259 Received 24 Apr 2017; Accepted 24 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: In this paper, we proposed a new method, which combines random pattern illumination, patternestimationalgorithm and FP algorithm, to recover a super resolution image. We shift one multi-spot pattern todifferent positions to capture images, and estimate these illumination patterns using a novel algorithm whichshares the same root with blind SIM. Based on the captured images and estimated patterns, FP algorithm is thenapplied to recover a super resolution image. Our method, termed as Pattern-estimated Fourier ptychography(PEFP) microscopy, does not need the prior information about the scanning position, thus insensitive to rotationalerrors and shift errors. The performance of PEFP has been demonstrated both in simulations and experiments.And PEFP could achieve better resolution than pattern-illuminated Fourier ptychography (FP) method when shifterrors appears in our simulations. Compared with a newly proposed blind SIM method, PEFP also shows betterresolution enhancement both in our simulations and experiments. Our method also provides the possibility toextend the application of pattern-illuminated FP to any pattern illumination because we estimated everyillumination pattern separately as blind SIM does.

Compressive Correlation Holography

RACHIT SALUJA, Sai Subrahmanyam Gorthi, Deepak Mishra, VINU RV, and Rakesh Singh

Doc ID: 295419 Received 22 May 2017; Accepted 24 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: We propose and demonstrate a compressive sensing(CS) framework for correlation holography. This is ac-complished by adopting the principle of compressivesensing and thresholding in the two point intensitycorrelation. The measurement matrix and the sensingmatrix that is required for applying the CS frameworkhere are systematically extracted from the random illu-minations of the laser speckle data. Reconstruction re-sults using CS, CS with thresholding and intensity cor-relation are compared. Our study reveals that liminalCS requires far fewer samples for the reconstruction ofthe hologram and has wide application in image recon-struction.

Continuously tunable mode-spacing of dual-modeexternal cavity InAs/InP quantum dot laser

Hui-Hong Yuan, Feng Gao, and Tao Yang

Doc ID: 296234 Received 01 Jun 2017; Accepted 24 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: Tunable double-mode external cavity InAs/InP quantum dot laser based on a dual-Littrow configuration isdemonstrated. A 115nm single mode tuning spectrum with obviously varied mode intensity has been obtained. Amodified tuning method has been adopted to realize continuously tunable mode-spacing between two modes. It isfound that single and double modes coexisted in the tuning spectrum when one grating angle is fixed while theother grating is rotated; the biggest mode-spacing between double modes is about 75nm. Continuously tunablerange of mode-spacing between double wavelengths has reached up to 80nm by inserting an attenuation slice inthe external optical feedback paths to balance the intensity of the double modes; the separation of double modes isabout 50nm at best. The average output power of the double-mode laser is about a few milliwatts.

Effect of laser intensity on temporal and spectral features of laser generated acoustic shock waves: ns vs ps laser pulses

Manikanta Elle, Vinoth Kumar L Lakshmi Narayanan R, Leela Chelikani, and Prem Kiran Paturi

Doc ID: 296485 Received 22 May 2017; Accepted 24 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: Evolution of acoustic shock wave (ASW) properties generated during ns- and ps- laser induced breakdown (LIB) ofatmospheric air at different input intensities is presented. The intensity is varied by changing focal geometry of nsand ps pulses. The ASW pressures are observed to follow the dynamic interplay between the plasma density andrecombination of plasma species. The conversion of laser energy to acoustic energy has increased from loose totight focusing conditions. The central frequencies have moved towards the lower side with increasing laserintensities for both ns-LIB (76 to 48 kHz) and ps-LIB (111.2 to 92.1 kHz). The angular distribution of acousticemissions was observed to follow the laser induced plasma spark in both ns- and ps-LIB.

A new scheme for achieving continuous-wavelaser operation at 1178 nm

huanian Zhang, Ping Li, and xiaohan chen

Doc ID: 296702 Received 24 May 2017; Accepted 23 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: We report, for the first time to our knowledge, a new scheme for generating the important 1178 nm laser. Based ona high power 1018 nm fiber laser as a pump source and CVD-diamond as a Raman gain medium, the Raman laserwas capable of generating 34.6 W output power centered at 1178.02 nm. As far as we known, 34.6 W is the highestoutput power of a 1178 nm laser obtained within a crystalline Raman gain medium. The experimental resultsshow the superiority of our scheme in obtaining 1178 nm laser generation.

Comparison of hyperspectral imaging spectrometer designs and the improvement of system performance with freeform surfaces

Chang Liu, Christoph Straif, Thomas Flügel-Paul, Uwe Zeitner, and Herbert Gross

Doc ID: 291097 Received 22 Mar 2017; Accepted 23 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: Hyperspectral grating based imaging spectrometer systems with F/3 and covering the VNIR (420 nm-1000nm) spectral range are investigated for monitoring Earth’s environmental change. The systems have an entrance slit of 24 µm and a 6.5 nm spectral resolution. Both smile and keystone distortions are smaller than 20% of the pixel pitch. We benefit from the development in freeform technology and design 13 different systems with the help of off-axis aspheric and freeform surfaces. The potential of each system is explored with the help of non-spherical surfaces. Cross comparisons between different mirror types are summarized to give their advantages and disadvantages. In the end, detailed tolerancing of one selected system is presented to show the feasibility for fabrication.

Measurement error analysis for polarization extinction ratio of multi-functional integrated optic chips

Haoliang Zhang, Jun Yang, Chuang Li, Zhangjun Yu, Zhe Yang, yuan yonggui, Feng Peng, Hanyang Li, Changbo Hou, Jianzhong Zhang, Libo Yuan, Jianming Xu, and Chao Zhang

Doc ID: 292009 Received 07 Apr 2017; Accepted 23 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: Measurement error for the polarization extinction ratio (PER) of multi-functional integrated optic chip (MFIOC) utilizing white light interferometry was analyzed. Three influence factors derived from the all-fiber device (or optical circuit) under test were demonstrated to be the main error sources, including: 1) the axis-alignment angle (AA) of connection point between the extended polarization-maintaining fiber (PMF) and the chip PMF pigtail, 2) the oriented angle (OA) of linear polarizer and 3) the birefringence dispersion of PMF and MFIOC chip. Theoretical calculations and experimental results indicated that by controlling the AA range within 0°±5°, the OA range within 45°±2° and combining with dispersion compensation process, the maximal PER measurement error can be limited to under 1.4 dB, with the 3σ uncertainty of 0.3 dB. The variations of birefringence dispersion effect versus PMF length were also discussed to further confirm the validity of dispersion compensation. A MFIOC with the PER of ~50 dB was experimentally tested and the total measurement error was calculated to be ~0.7 dB, which proved the effectiveness of the proposed error reduction methods. We believe that these methods are able to facilitate high-accuracy PER measurement.

Random Bit Generation using Coherent State andThreshold Detectors at 1550 nanometers

Elisa Carneiro, Felipe Calliari, Gustavo do Amaral, and Guilherme Temporao

Doc ID: 295958 Received 15 May 2017; Accepted 23 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: We theoretically propose and experimentally validate a practical random bit generation method based onthe detections of a coherent state in the few-photon regime by a gated single-photon threshold detectoroperating at the telecom wavelength of 1550 nanometers. By fine-tuning the mean number of photons perpulse of a laser beam directed to the single-photon detector, a fifty-fifty chance of detection or no-detectionis reached; under this condition, detections inside the gate window are treated as ’1’s, while ’0’s are associatedto the absence of detections. The same method could also be applied in a free-running single-photondetector for increased throughput by chopping the light signal instead of gating the detector. Both hardwareimplementations yielded bit strings which were evaluated by a standard randomness test suite withgood confidence. Despite the yet low rates achieved by the proposed method, its hardware compatibilitywith Quantum Key Distribution setups make it an interesting candidate for random number generationwithin the context of practical Quantum Communications.

A new frequency estimation method for frequencymodulated continuous wave laser ranging

Pan Hao, FuMin Zhang, shi zhao, and XingHua Qu

Doc ID: 296947 Received 30 May 2017; Accepted 22 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: The long fiber frequency sampling method is diffusely used to eliminate the non-linearity of laser tuning infrequency modulated continuous wave laser detection and ranging (FMCW ladar) technique. However, although ithas high precision, it is affected by the picket fence effect and spectrum leakage. In this paper, we propose a newfrequency estimation method, multiple signal classification (MUSIC), to be used instead of the conventional FFTbasedalgorithm in order to obtain better range precision. The proposed method was verified by experiments. Inthe experiments, when the distance was up to 3.814 m and chirped bandwidth was equal to 20 nm (2.5THz), theFWHM of range peak, which represented the estimated precision of frequency obtained by MUSIC, was 20 um, andit was improved for 7 times compared to FFT-based method. Meanwhile, to evaluate the performance of proposedmethod, the frequency estimation according to the Cramer-Rao lower bound (CRLB) was also performed. Theexperimental results have shown that the mean square error of distance estimation based on MUSIC algorithm is0.56 um, which is much closer to CRLB of 0.18um than the mean square error of conventional FFT-based method.Furthermore, we demonstrated that MUSIC estimator has an unparalleled advantage over another estimator in thehigh precision ranging fields.

Confocal Laser Displacement Sensor Using MicromachinedVarifocal Mirror

Kenta Nakazawa, Takashi Sasaki, Hiromasa Furuta, Jiro Kamiya, Hideki Sasaki, Toshikazu Kamiya, and Kazuhiro Hane

Doc ID: 297930 Received 12 Jun 2017; Accepted 22 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: A confocal laser displacement sensor using a micro-machined varifocal mirror is reported. The focal lengthmodulation is a key function of the confocal sensor. The mechanism of the focal length modulation determines themeasurement speed and range. Here, we propose application the micro-machined varifocal mirror for themodulation. The varifocal mirror can realize faster modulation, small size, and low energy consumption for theconfocal displacement sensor. The electrostatically actuated varifocal mirror made by single crystalline silicon isused. The working distance of the sensor is designed to be 31 mm. The actuating range at 7 kHz is 310 μm. Thelinearity error in the actuating range is from -1.1% to 1.2%.

Polarization properties of receiving telescopes in atmospheric remote sensing polarization lidars

jing luo, Dong Liu, zihao huang, Jian Bai, Zhongtao Cheng, Yupeng Zhang, Peijun Tang, Liming Yang, and lin su

Doc ID: 295119 Received 03 May 2017; Accepted 22 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: Receiving telescope is an indispensable component in an atmospheric remote sensing polarization lidar. In order to achieve accurate atmospheric depolarization measurements, it is necessary to study the polarization properties of receiving telescopes, which are embodied by their Mueller matrices. In this paper, the Mueller matrices of receiving telescopes are obtained by ray tracing with space vector. The relationship between the measurement errors of the atmospheric depolarization parameter and the elements of telescopic Mueller matrix is built. The polarization properties of receiving telescopes in terms of orientation, field of view and number are analyzed, respectively. By comparing several common receiving telescopes in linear and circular polarization lidars, it is found that the measurement errors caused by the Newton telescope in circular polarization lidars are significantly greater than those in linear polarization lidars, while the performances of the Cassegrain telescope in the two cases are almost identical. What is more, the measurement errors caused by the Cassegrain telescope are much less than the counterpart caused by the Newton telescope. According to the comparison results, the optimal telescopes are respectively chosen for polarization lidars working in different polarization states and laser wavelengths.

Ultrasound-to-plastic optical fiber coupling as acoustic source probe

Tingting Gang, Manli Hu, Yongxin Hao, Ruixiang Zhou, Rongxin Tong, Xue-Guang Qiao, and Qiangzhou Rong

Doc ID: 295669 Received 09 May 2017; Accepted 21 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: An integrated ultrasonic detection system which consists of emission and detection has been proposed anddemonstrated experimentally. The proposed emission source is based on plastic optical fiber (POF). In order topromote the coupling of ultrasound-to-POF, and the end of POF is heated to form a circular pedestal. A home-madefiber Fabry-Perot (FP) interferometer is employed to evaluate the coupling efficiency of ultrasound-to-POF. Thesensing head is spliced a short section of hollow core fiber (HCF) and single mode fiber (SMF), resulting in an airmicro-bubble formation by discharging. The experimental results show that ultrasound can be transmittedeffectively in a narrow space using the coupling method, and the compact sensor also presents a consideredsensitivity for ultrasonic detection. This all-fiber ultrasonic interrogation can be integrated as a system for theapplication in bio-imaging field, especially the organism body.

Re-examining the effect of particle phase functions on the remote-sensing reflectance

Yuanheng Xiong, Xiaodong Zhang, Shuangyan He, and Deric Gray

Doc ID: 296192 Received 17 May 2017; Accepted 21 Jul 2017; Posted 24 Jul 2017  View: PDF

Abstract: Even though it is well known that both the magnitude and shape of the volume scattering function (VSF), particularly in the backward angles, affect the color of the ocean, the current remote sensing reflectance (Rrs) models typically only account for the effect of its magnitude through the backscattering coefficient. Using 116 VSF data sets that we have collected in three coastal waters around the US and in the water of North Atlantic Ocean, we re-examined the effect of VSF shapes on Rrs in three scenarios with increasingly stringent constraints on the backscattering. For nadir-viewed Rrs, only accounting for the magnitude of backscattering (i.e., bb) and ignoring the shape would induce up to 65% uncertainty; accounting for both bb and the general backward shape (defined by the backscattering ratio ) would induce up to 35% uncertainty; and accounting for both bb and the exact backward shape (defined by the χ factor) would induce up to 10% uncertainty. In all three scenarios, the uncertainty increases with both viewing and sun angles and is most prominent in the opposite direction of the sun. Our results show a greater impact of the VSF shape on Rrs than previous found mainly because our VSF data show a much greater variability in both bb ratio and the χ factor than previously known. Among the uncertainties in Rrs due to the shape of a VSF, about 97% can be explained by the exact backward shape (χ), 27% by the general backward shape (bb ratio), and < 3% by the exact forward shape. The results indicate the uncertainty in ocean color remote sensing can be significantly constrained by accounting for χ of the VSFs.

Non-perturbing voltage measurement in a coaxial cable with slab-coupled optical sensors

Nikola Stan, Frederick Seng, LeGrand Shumway, Rex King, and Stephen Schultz

Doc ID: 295552 Received 24 May 2017; Accepted 20 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: Voltage in a coaxial cable is measured by an electric-field optical fiber sensor exploiting the proportionality of voltage and electric field in a fixed structure. Sensor is inserted in a hole drilled through the dielectric of the RG-218 coaxial cable and sealed with epoxy to displace all air and prevent the adverse effects of charge build-up during high voltage measurements. It is shown that the presence of the sensor in the coaxial cable does not significantly increase electrical reflections in the cable. Slab coupled optical fiber sensor (SCOS) is used for its compact size and dielectric make. The dynamic range of 50 dB is shown experimentally with detection of signals as low as 1 V and up to 157 kV. A low corner of 0.3 Hz is demonstrated and SCOS is shown to be able to measure 90 ns rise times.

Joint Sparse and Low Rank Recovery Algorithm forCompressive Hyperspectral Imaging

Tatiana Gelvez, Hoover Rueda, and Henry Fuentes

Doc ID: 293275 Received 21 Apr 2017; Accepted 20 Jul 2017; Posted 21 Jul 2017  View: PDF

Abstract: Compressive spectral imaging techniques encode and disperse a hyperspectral image (HSI) to sense its spatial and spectral information with few bidimensional (2D) multiplexed projections. Recovering theoriginal HSI from the 2D projections is carried by traditional compressive sensing based techniques that exploit the sparsity property of natural HSI as they are represented in a proper orthonormal basis. Nevertheless, HSIs also exhibit a low rank property inasmuch only a few number of spectral signatures are present in the images. Specifically, when an HSI is rearranged as a matrix whose columns represent vectorized 2D spatial images in a different wavelength, this matrix is said to be low rank. Therefore, this paperproposes an HSI recovering algorithm from compressed measurements involving a joint sparse and low rank optimization problem which seeks to jointly minimize the L2, L1, and nuclear norm, leading the solutionto fit the given projections, and be simultaneously sparse and low rank. Several simulations, along different data sets and optical sensing architectures, show that when the low rank property is included in theinverse problem formulation, the reconstruction quality increases up to 4 [dB] in terms of PSNR.

Weighted reconstruction of three-dimensional refractive index in interferometric tomography

Satoshi Tomioka, Shusuke Nishiyama, Naoki Miyamoto, Daichi Kando, and Samia Heshmat

Doc ID: 296908 Received 30 May 2017; Accepted 20 Jul 2017; Posted 21 Jul 2017  View: PDF

Abstract: Interferometric tomography can reconstruct three-dimensional refractive-index distributions through phase-shift measurements for different beam angles. To reconstruct a complex refractive-index distribution, many projections along different directions are required.For the purpose of increasing the number of the projections, we earlier proposed a beam-angle-controllable interferometer with mechanical stages; however, the quality of reconstructed distribution by conventional algorithms was poor since the background fringes cannot be controlled precisely. To improve the quality, we propose a weighted reconstruction algorithm that can consider projection errors. We demonstrate the validity of the weighted reconstruction through simulations and a reconstruction from experimental data for three candle flames.

Affordable Dispersion Mitigation Method for the Next Generation RF-over-Fiber Optical Channels

shalom bloch, Shmuel Sternklar, and Er'el Granot

Doc ID: 297761 Received 08 Jun 2017; Accepted 20 Jul 2017; Posted 21 Jul 2017  View: PDF

Abstract: Next-generation analog RF-over-Fiber links will require dispersion compensation. Most dispersion compensation methods are based on additional optical elements. Therefore, these solutions may be inadequate for low-cost channels. In this work we suggest a novel low-cost dispersion compensation solution for RF-over-Fiber (RFoF) links. The method is based on two properties, which are common in these links: the modulation depth in analog RFoF links is lower than in digital links (and to avoid nonlinearities it may be deliberately set to a small value), and the data is carried by a high frequency carrier. It is shown that with these properties, the optical channel behaves approximately as a linear system. The distortion occurs in the linear domain and in the third harmonic regime. Since the third harmonic distortions are usually smaller than the back-to-back distortions, they are linear in the power domain. We therefore suggest using a simple low-cost electronic filter to compensate the dispersion distortions. The performance of this technique is presented both analytically and with a numerical simulation. These preliminary results are very encouraging, and point to an inexpensive solution for next-generation RFoF links to the home.

Computer-aided-design (CAD) model assisted absolute three-dimensional shape measurement

Beiwen Li, Tyler Bell, and Song Zhang

Doc ID: 300740 Received 22 Jun 2017; Accepted 20 Jul 2017; Posted 21 Jul 2017  View: PDF

Abstract: Conventional three-dimensional (3D) shape measurement methods are typically generic to all types of objects. Yet, for many measurement conditions, such level of generality is inessential when having the pre-knowledge of object geometry. This paper introduces a novel adaptive algorithm for absolute 3D shape shape measurement with the assistance of the object CAD model. The proposed algorithm includes the following major steps: 1) export the 3D point cloud data from the CAD model; 2) transform the CAD model into the camera perspective; 3) obtain wrapped phase map from three phase-shifted fringe images; 4) retrieve absolute phase and 3D geometry assisted by CAD model. We demonstrate that if object CAD models are available, such algorithm is efficient in recovering absolute 3D geometries of both simple and complex objects with only three phase-shifted fringe images.

Velocity Measurement based on Multiple Self-Mixing Interference

XIUYAN ZHANG, WANYING GU, Chunlei Jiang, BINGKUN GAO, and peng chen

Doc ID: 294931 Received 05 May 2017; Accepted 20 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: This study proposes a novel algorithm based on multiple self-mixing interference (MSMI) theory to measure the velocity of a remote target without contact. The principle of MSMI is presented and the corresponding formulas for velocity measurement are derived. Fast Fourier transform (FFT) is applied to detect signal frequency and calculate velocity values. A low-cost, compact, and easy-to-operate experimental setup is also constructed. Experiments are conducted to validate the correctness of our novel algorithm. This algorithm can improve resolution more easily than conventional self-mixing interference (SMI) methods.

Laser confocal cylindrical radius measurement method and its system

Yang Xiao, Lirong Qiu, and Weiqian Zhao

Doc ID: 295330 Received 09 May 2017; Accepted 19 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: This paper proposes a laser confocal cylindrical radius measurement (CCRM) method. CCRM method precisely identifies the positions of the vertex and curvature center of the test cylindrical surface by using the property that the maximum point of the laser confocal axial intensity curve precisely corresponds to the focus of the laser confocal measurement system, and the accurate distance of these two positions is obtained by the distance measuring instrument, thus achieving the precise measurement of cylindrical radius. And the quadratic fitting method is used to further improve the measurement accuracy. Comparing with the existing measurement methods, the CCRM method has high measurement precision, simple structure and strong environmental anti-interference capability, and it is more suitable for engineering application. Based on CCRM, the CCRM system is established and theoretical analysis and preliminary experiments indicate that the relative uncertainty of cylindrical radius measurement is better than 0.045%. Therefore, CCRM provides an effective approach for the high-precision measurement of cylindrical radius.

3D Pose Estimation of Large and Complicated Workpieces based onBinocular Stereo Vision

Zhifeng Luo, Ke Zhang, Zhigang Wang, Jian Zheng, and Yixin Chen

Doc ID: 285009 Received 22 May 2017; Accepted 19 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: A binocular stereo vision method is proposed for automatically locating the position andposture of workpieces, which is especially important when processing large, complicatedstructures, for example, the laser hardening and laser cladding of automotive die. First, a binocularstereo vision positioning system was designed and modeled, from which a method of backgroundsubtraction was proposed to extract the edge line of the foreground area. Furthermore, theintersection point of the workpiece contour line was taken as the characteristic point of theworkpiece, an algorithm that combines epipolar constraint with gray value similarity wasproposed to realize quickly and accurately the feature points matching. Finally, experiments showthat the workpiece can be positioned accurately and that the precision of position recognitioncould be controlled within ± 0.5 mm when the camera was 1 m away from the workpiece, meetingthe requirement of robot processing.

Laboratory demonstration of a cryogenic deformablemirror for wavefront correction of space-borne infraredtelescopes

Aoi Takahashi, Keigo Enya, Kanae Haze, Hirokazu Kataza, Takayuki Kotani, Hideo Matsuhara, Tomohiro Kamiya, Tomoyasu Yamamuro, Paul Bierden, Steven Cornelissen, Charlie Lam, and Michael Feinberg

Doc ID: 291195 Received 24 Mar 2017; Accepted 19 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: This paper demonstrates a cryogenic deformable mirror (DM) with 1,020 actuators based on microelectricalmechanical systems (MEMS) technology. Cryogenic space-borne infrared telescopes canexperience a wavefront error due to a figure error of their mirror surface, which makes the imagingperformance worse. For on-orbit wavefront correction as one solution, we developed a MEMS-processedelectro-static DM with a special surrounding structure for use under the cryogenic temperature. Weconducted a laboratory demonstration of its operation in three cooling cycles between 5 K and 295 K.Using a laser interferometer, we detected the deformation corresponding to the applied voltages underthe cryogenic temperature for the first time. The relationship between voltages and displacementswas qualitatively expressed by the quadratic function, which is assumed based on the principle ofelectro-static DMs. We also found that it had a high operating repeatability of a few nm RMS and nosignificant hysteresis. Using the measured values of repeatability, we simulated the improvement ofPSF by wavefront correction with our DM. These results show that our developed DM is effective inimproving imaging performance and PSF contrast of space-borne infrared telescopes.

Point target detection based on multiscale morphological filtering and energy concentration criterion

Rang Liu, dejiang wang, Dabiao Zhou, and Ping Jia

Doc ID: 291641 Received 31 Mar 2017; Accepted 19 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: The research on optical imaging characteristics of infrared dim point target is necessary for target detection. We analyze the energy focusability of point target and propose a simulation model of target imaging process. Then we use 8-directions structural elements to detect all the possible targets. The adaptive threshold and energy focusability criterion are adopt to eliminate interference. Finally, the trajectory of point target is obtained after the low-order recursive correlation. The results show that the detection probability of the proposed method reaches 99.80% with 0.2% false alarm probability. It demonstrates that this method has a good performance to suppress complex background and noise. Also it has the advantage of low complexity and easy implementation in real-time system.

Sampling Moiré Technique for Determination of Optical Transfer Function of Digital Imaging Systems

Soheila Javadian Varjovi and Khosro Madanipour

Doc ID: 292097 Received 04 Apr 2017; Accepted 19 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: In this paper, the optical transfer function (OTF) of a digital imaging system is determined by different frequencies sinusoidal gratings in two stages of before and after of the Nyquist frequency. Before the Nyquist frequency, modulation transfer function (MTF) and visibility are equivalent and the phase transfer function (PTF) doesn’t change with phase variation of the initial object gratings. Sampling of the grating with frequency above the Nyquist frequency give rise to sampling moiré fringes. In this situation the MTF is unusually bigger than 1 and isn’t equivalent the visibility of the sampling moiré. But the PTF shows two different behaviors before and after the Nyquist frequency. Before the Nyquist frequency the PTF doesn’t depend on the initial phase variation of the grating but after the Nyquist frequency the PTF depends on the initial phase variation. Therefore, the PTF of the sampling moiré is proposed for the phase variation detection.

Adaptive Optics Retinal Imaging with AutomaticDetection of the Pupil and its Boundary in Real timeusing Shack Hartmann Images

Alberto de Castro, Lucie Sawides, Xiaofeng Qi, and Stephen Burns

Doc ID: 292377 Received 13 Apr 2017; Accepted 19 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: Retinal imaging with an adaptive optics system usually requires that the eye be centered and stablerelative to the exit pupil of the system. Aberrations are then typically corrected inside a fixedcircular pupil. This approach can be restrictive when imaging some subjects since the pupil maynot be round and maintaining a stable head position can be difficult. In this paper we present anautomatic algorithm that relaxes these constraints. An image quality metric is computed for eachspot of the Shack Hartmann image to detect the pupil and its boundary and the control algorithm isapplied only to regions within the subject’s pupil. Images on a model eye as well as for five subjectswere obtained to show that a system exit pupil larger than the subject’s eye pupil could be used forAO retinal imaging without a reduction in image quality. This algorithm automates the task ofselecting pupil size. It also may relax constrains on centering the subject’s pupil and on the shape ofthe pupil.

One-step real-virtual combined reflection hologram: a4f relay approach

Jian Su, Yingqing Huang, Yibei Chen, Xiaoyu Jiang, and Xingpeng Yan

Doc ID: 294838 Received 28 Apr 2017; Accepted 19 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: Producing of conventional optical reflection hologram can be classified into one-step method and two-step method. In one-step method, only the diverging light of the object could be recorded, and the reconstructed scene is a virtual one behind the recording medium. In two-step method, the diverging light or the converging light could be recorded alternatively. However, the process is complicated considering double exposures. The object is first imaged by a 4f system, then the interference patterns are recorded by single exposure. The reconstructed image can be either a virtual image behind the recording medium, or a real image in front of the recording medium. The ideal imaging property of 4f system has been demonstrated theoretically and the proposed method has been verified experimentally.

Design of all-optical fractional-order differentiatorwith THz-bandwidth based on fiber Bragg grating intransmission

Xin Liu and Xuewen Shu

Doc ID: 294620 Received 26 Apr 2017; Accepted 18 Jul 2017; Posted 18 Jul 2017  View: PDF

Abstract: All-optical fractional-order temporal differentiators with bandwidth reaching THz are demonstrated withtransmissive fiber Bragg gratings (FBGs). Since the designed fractional-order differentiator is a minimum phasefunction, the reflective phase of the designed function can be chosen arbitrarily. As examples, we first designseveral 0.5th-order differentiators with bandwidth reaching THz range for comparison. The reflective phases of the0.5th-order differentiator are chosen to be linear phase, quadratic phase, cubic phase and biquadratic phase,respectively. We find that both the maximum coupling coefficient and the spatial resolution of the designed gratingincrease when the reflective phase varies from quadratic function to cubic function to biquadratic function. Andwhen the reflective phase is chosen to be a quadratic function, the obtained grating coupling coefficient and periodare more likely to be achieved in practice. Then we design fractional-order differentiators with different orderswhen the reflective phase is chosen to be a quadratic function. We see that when the designed order of thedifferentiator increases, the obtained maximum coupling coefficient also increases while the oscillation of thecoupling coefficient decreases. Finally, we give the numerical performance of the designed 0.5th-orderdifferentiator by showing its temporal response and calculating its cross-correlation coefficient.

MEMS tracking mirror system for bidirectional free-space optical link

Hiroshi Toshiyoshi and Sungho Jeon

Doc ID: 297630 Received 08 Jun 2017; Accepted 18 Jul 2017; Posted 18 Jul 2017  View: PDF

Abstract: We report on a bidirectional free space optical system that is capable of automatic connection and tracking of optical link between two nodes. A piezoelectric microelectromechanical systems (MEMS) optical scanner is used to steer a laser beam of two wavelengths superposed to visually present a communication zone, to search for the position of the remote node by means of the retro-reflector optics, and to transmit the data between the nodes. A feedback system is developed to control the MEMS scanner to dynamically establish the optical link within a 10-ms transition time and to keep track of the moving node.

Brewster-angle 50%-50% beam splitter for p-polarized IR light using a high-index quarter-wave layer deposited on a low-index prism

Rasheed Azzam

Doc ID: 297774 Received 09 Jun 2017; Accepted 18 Jul 2017; Posted 18 Jul 2017  View: PDF

Abstract: A quarter-wave layer (QWL) of high refractive index, which is deposited on a transparent prism of low refractive index, can be designed to split an incident p-polarized light beam at the Brewster angle (BA) of air-substrate interface into p-polarized reflected and transmitted beams of equal intensity (50% each) that travel in orthogonal directions. For incident p-polarized light at the BA, the supported QWL functions as a free-standing (unsupported) pellicle. An exemplary design is presented that uses SixGe1-x QWL deposited on IRTRAN1 prism for applications (such as Michelson and Mach-Zehnder interferometry) with a variable compositional fraction x in the 2 - 6 µm mid-IR spectral range.

Directional backlighting system using a light guide with paired microstructures

Rui Zhang

Doc ID: 291032 Received 02 May 2017; Accepted 18 Jul 2017; Posted 19 Jul 2017  View: PDF

Abstract: In a conventional edge-lit backlighting system, a light guide with diffusing dots, prism films and diffusers are used to produce desired light distribution. In such a system, the use of prism films helps to collimate the light, but it also increases the cost and reduces the overall optical efficiency. This paper proposes a novel light guide with paired microstructures to produce highly collimated light distribution without using prism films. Each paired microstructure is composed of two different micro-geometries which are placed next to each other. By optimizing the surface angles of paired microstructure in the light guide, a highly collimated light distribution can be generated without using prism films.

Complexity-Enhanced Polarization-Resolved Chaos in a Ring Network of Mutually-Coupled VCSELs with Multiple Delays

Hao Zhang, Shuiying Xiang, Yahui Zhang, and Xingxing Guo

Doc ID: 300655 Received 21 Jun 2017; Accepted 18 Jul 2017; Posted 19 Jul 2017  View: PDF

Abstract: The complexity properties of polarization-resolved chaotic signals generated in a ring network of vertical-cavity surface-emitting lasers (VCSELs) mutually-coupled with multiple delays are investigated quantitatively, by using the proposed mean permutation entropy (MPE). For the purpose of direct comparison, the complexity of polarization-resolved chaos in a ring network of VCSELs coupled with single delay is also considered. The effects of injection current, coupling strength, and frequency detuning on the chaotic complexity for both single delay ring network (SDRN) and multiple delays ring network (MDRN) are evaluated quantitatively and compared by the MPE. The effects of internal parameters of VCSELs on the complexity are also discussed, and the correlation properties between different polarization-resolved modes are also analyzed. It is shown that, the complexity of chaos in two polarization-resolved modes of VCSELs in MDRN is much higher than those in SDRN in much wider parameter region. Besides, wider range of injection current, coupling strength and frequency detuning can be tuned to achieve the enhancement of chaotic complexity in MDRN. These results provide an effective quantifier, the proposed MPE, to evaluate quantitatively the complexity of chaos generated in systems with multiple delays, and the multi-channel complexity-enhanced polarization-resolved chaos generated in MDRN of mutually-coupled VCSELs is extremely meaningful for the chaos-based random number generators.

Far infrared micro-spectroscopy: an innovativemethod to detect individual Metal-OrganicFramework particles

Jean-Michel ORTEGA, francois glotin, Rui Prazeres, Xue Li, and ruxandra gref

Doc ID: 297671 Received 08 Jun 2017; Accepted 18 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: The purpose of this study is to extend the spectral range of a differential method of infrared micro-spectroscopy (AFMIR) in order to allow the accurate detection of nanoparticles of interest for biomedical applications. Among these, Metal-Organic Framework (MOF) nanoparticles attracted increasing interest due to their capacity to incorporate high drug payloads, biodegradability and possibility to tailor their surface by grafting specific ligands. However, MOF particle detection in biological media without grafting or incorporating fluorescent molecules is challenging. We took advantage here of the presence of the specific adsorption bands of nanoMOFs in far infrared in order to individually discriminate them. Here we show that single MOF nanoparticles can be imaged with a spatial resolution of a few tenths of a nanometer.

A depth estimation algorithm for light field data by epipolar image analysis and region interpolation

Zhuang Ma, Zhaofeng Cen, and Xiaotong Li

Doc ID: 295038 Received 22 May 2017; Accepted 17 Jul 2017; Posted 18 Jul 2017  View: PDF

Abstract: In this paper, we propose an optimized algorithm to estimate the depth information in the 4D light field data. Our scheme has an advantage of conciseness compared with the traditional EPI analysis method. First of all, we have analyzed the depth resolution properties of light field data which is not mentioned by the previous researchers. In the depth estimation process, epipolar analysis is confined in a small range to reduce the running time, combining with regression test to reduce estimation error. Occlusion condition is specially dealt by recognizing object margin. To test the accuracy of our algorithm, we use a benchmark dataset to evaluate the output depth result. We get competitive result in the estimation error evaluation and prevailing runtime result compared with baseline algorithms.

Effects of Interface Thermal Resistance on SurfaceMorphology Evolution in Precision Glass Molding forMicrolens Array

Jiaqing Xie, Tianfeng Zhou, Benshuai Ruan, Yifei Du, and Xibin Wang

Doc ID: 295222 Received 04 May 2017; Accepted 17 Jul 2017; Posted 18 Jul 2017  View: PDF

Abstract: To study the effects of the interface thermal resistance on surfacemorphology evolution in precision glass molding (PGM) for microlens array withdifferent mold materials, including Tungsten carbide (WC) and heat-resistant stainlesssteel (310S), the glass-mold interface thermal resistance is calculated, and heat-transfersimulation of PGM based on interface thermal resistance model at heating stage isconducted correspondingly. The effect of flattening behavior on glass-mold interface isexplained. Then, experiments evaluating the relationship between heating time andglass surface roughness are carried out, the glass adhesion phenomenon appeared onthe heat-resistant stainless steel mold is observed and analysed. Finally, microlens arrayis fabricated on the Nickel Phosphorous (Ni-P) plating layer on the heat-resistantstainless steel substrate by diamond ball-nose end milling, and experiments of PGM formicrolens array are carried out to verify the interface thermal resistance model. Theresult shows that high quality surface can be obtained by the combination of smoothmold-rough glass. Compared with the microlens array fabricated with the rough glasspreform, using the smooth glass preform achieves higher form accuracy without defectsand blurs.

Statistical properties of rectangular cusped random beams propagating in oceanic turbulence

Chuanyi Lu and Daomu Zhao

Doc ID: 296881 Received 30 May 2017; Accepted 17 Jul 2017; Posted 17 Jul 2017  View: PDF

Abstract: The analytical formula for the cross-spectral density function of the rectangular cusped random beams, also known as fractional multi-Gaussian Schell-model beams, propagating in oceanic turbulence is derived. The statistical properties incorporating the spectral density and the spectral degree of coherence of the beams on propagation are investigated. It is found that the beams maintain rectangular-shaped cusped profile in weak turbulence just as in free space, whereas in strong turbulence or at sufficiently long propagation distances the beams profile would be destroyed little by little, turning out to be Gaussian profile eventually. Moreover, the beams with smaller coherence length exhibit more obvious rectangular outline. In addition, the spectral density and the spectral degree of coherence are both affected by various turbulence parameters.

Reduction of chromatic dispersion using multiplecarrier frequency patterns in SLM-based microscopy

Shima Gharbi, Hao Pang, Christian Lingel, Tobias Haist, and Wolfgang Osten

Doc ID: 296503 Received 22 May 2017; Accepted 17 Jul 2017; Posted 17 Jul 2017  View: PDF

Abstract: Typically, spatial light modulator (SLM)-based microscopy is implemented using a carrier frequencyin order to avoid disturbances due to the non-ideal modulation behavior of most SLMs. However, incombination with polychromatic light this leads to strong chromatic aberrations due to the dispersionat the grating formed by the carrier frequency. In this contribution we introduce a method based on theevaluation of multiple images obtained with different carrier frequency orientations. This way, chromaticaberrations and the limitation concerning the object field can be strongly reduced.

Color-image reconstruction for two-wavelength digital holography using a generalized phase-shifting approach

Takaaki Shiratori, KEISUKE KASAI, and Nobukazu Yoshikawa

Doc ID: 295161 Received 03 May 2017; Accepted 17 Jul 2017; Posted 17 Jul 2017  View: PDF

Abstract: We propose a color image reconstruction method for two-wavelength digital holography using generalized phase-shifting digital holography (GPSDH). In this method, color interference fringes are captured by a digital camera with a Bayer array color filter, and phase-shifting is simultaneously performed for all wavelengths. Color interference fringes are separated into three monochromatic interference fringes using a color separation method that suppresses the color filter crosstalk. The object wave is extracted from each monochromatic interference fringe using GPSDH, which prevents problems concerning the wavelength dependence of the phase shift. Image reconstruction is performed by a shifted Fresnel transform-based method, in which the color reconstructed image is obtained by directly superposing the reconstructed images for all wavelengths. We verify the proposed method by optical experiments with a two-wavelength digital holography system. The results show that the dual-color image can be successfully reconstructed without chromatic aberration.

Experimental study of an optimized PSP-OSTBC scheme with m-PPM in ultraviolet scattering channel for optical MIMO system

Dahai Han, Yanjie Gu, and Min Zhang

Doc ID: 296076 Received 17 May 2017; Accepted 16 Jul 2017; Posted 17 Jul 2017  View: PDF

Abstract: An optimized scheme of pulse symmetrical position-orthogonal space-time block codes (PSP-OSTBC) is proposedand applied with m-pulse positions modulation (m-PPM) without the use of complex decoding algorithm in anoptical multi-input multi-output (MIMO) ultraviolet (UV) communication system. The proposed scheme breaksthrough the limitation of the traditional Alamouti Code and is suitable for high-order m-PPM in UV scatteringchannel that verified by both simulation experiments and field tests with specific parameters. The performances of1×1, 2×1 and 2×2_PSP-OSTBC system with 4-PPM are compared experimentally as the optimal tradeoff betweenmodification and coding in practical application. Meanwhile, the feasibility of the proposed scheme for 8-PPM isexamined by simulation experiment as well. The results suggest that the proposed scheme makes the systeminsensitive to the influence of path loss with a larger channel capacity, and a higher diversity gain and coding gainwith simple decoding algorithm will be achieved by employing the orthogonality of m-PPM in optical-MIMO-basedultraviolet scattering channel.

Influence of dead-time on detection efficiency and range performance of photon-counting laser radar that uses Geiger-mode avalanche photodiode

Zhijian Li, Jiancheng Lai, Chungyong Wang, Yan Wei, and Zhen-hua Li

Doc ID: 294898 Received 01 May 2017; Accepted 16 Jul 2017; Posted 17 Jul 2017  View: PDF

Abstract: Dead-time has a significant influence on detection efficiency and range performance of photon-counting laser radar (LADAR) system that uses Geiger-mode avalanche photodiode (GmAPD). In this paper, a rapid universal recursive model about the detecting probability of discrete time under various dead-times is proposed, which is verified on controlled parameters. Our model has advantages of fast computing speed and unifies multi-trigger, single-trigger and zero-dead-time models in one. The computing speed is one to two orders of magnitude faster than Gatt’s and Zhao’s models in short dead-time condition, with relative errors less than 0.001 and 10^-14 respectively. Then the detection efficiency and range accuracy and precision with various dead-times are theoretically calculated and Monte Carlo simulated under different parameters. As a result, dead-time shorter than the end time of the target makes better detection efficiency, however, results in worse range performance and dead-time longer than that keeps detection efficiency at a low level but provides a better range performance. We discover that noise is the key reason that makes the detection efficiency and range performance fluctuates periodically versus different dead-times and local optimum values of fluctuations occur when the dead-time is few nanoseconds around 1, 1/2, 1/3 or even 1/4 of the end time of the target and this phenomenon get more obviously when noise increases. What’s more, weaker noise level is crucial to the detection efficiency and narrow pulse width and nearer target position in range gate are very important factors to improve precision.

Noise reduction of air turbulence via quasi-common-path method

Yinzhu He, Shijie Zhao, Haoyun Wei, and Yan Li

Doc ID: 294559 Received 24 Apr 2017; Accepted 15 Jul 2017; Posted 17 Jul 2017  View: PDF

Abstract: In this paper, a quasi-common-path method to improve the stability of the laser measurement instruments isproposed. The method releases the strictness of the common path structure and enables to compensate errorscaused by air turbulence. A wavefront measurement system is set up to simultaneously detect both the wavefrontsof the quasi-common-path beams, of which the orthogonal distance varies from 0 to 4 times the beam diameter.The correlation coefficient between two wavefronts remains around 0.9 in turbulence, which verifies the feasibility.Based on the method, a three-axis interferometer whose measuring optical paths orthogonally split 30 mm isestablished and the stability of the optical paths is evaluated. The standard deviations of the displacement and thedisplacement difference at original point are about 0.31 μm and 0.006 μm, respectively. While these performanceproperties at 1 m are 1.14 μm and 0.02 μm, respectively. The experiment results show that quasi-common-pathbeams allow for stability improvement, which can also be widely used in the field of precision machinemanufacturing.

Localized surface plasmon sensor based on gold islandfilms using a hetero-core structured optical fiber

Ai Hosoki, Michiko Nishiyama, and Kazuhiro Watanabe

Doc ID: 295662 Received 19 May 2017; Accepted 15 Jul 2017; Posted 17 Jul 2017  View: PDF

Abstract: This paper reports the effect of applying a Au islands film to the hetero-core structured optical fiber, which is fabricated by annealing thin Au films of 3 nm and 5 nm thicknesses and its sensing performance for the RI changes. We experimentally observe that novel LSPR spectra for 1.333 RIU appear in the visible-to-near-infrared region depending on the shape of Au islands. The absorbance and spectral sensitivities for a given refractive index region of the tested solvents were obtained to be 4.81 Au/RIU and 517 nm/RIU, respectively, in the range of 1.333–1.384 RIU in the case of 5-nm-thick Au film annealed at 900°C.

Analysis of holographic laser adaptive optics systemusing deformable mirror

Yao Kainan, Jianli Wang, Xinyue Liu, Lu Chen, and Xudong Lin

Doc ID: 295217 Received 04 May 2017; Accepted 14 Jul 2017; Posted 17 Jul 2017  View: PDF

Abstract: We describe a closed-loop holographic laser adaptive optics system (HLAOS) based on a holographic wavefrontsensor (HWFS) and 21-element continuous surface piezoelectric deformable mirror (DM). The principle behindHWFSs is described. Then, the response sensitivity and crosstalk effect on the lowest 12 Zernike-modes ofaberration are analyzed. Next, the wavefront correction capability of the 21-element DM is analyzed. The closedloopcorrection of the HLAOS to a static aberration is then numerically simulated. We report a practicalimplementation of the HLAOS and compare the aberration compensation effect with a traditional adaptive opticssystem based on a 37-unit Shark-Hartmann sensor. The practically relevant parameters are analyzed and theexperimental results show that an HLAOS using a piezoelectric DM can achieve a correction capability comparableto that of a traditional adaptive optics system.

Feasibility study of a space-based high pulse energy 2-μm CO₂ IPDA lidar

Upendra Singh, Tamer Refaat, Syed Ismail, Kenneth Davis, Stephan Kawa, Robert Menzies, and Mulugeta Petros

Doc ID: 292945 Received 17 Apr 2017; Accepted 14 Jul 2017; Posted 14 Jul 2017  View: PDF

Abstract: Sustained high-quality column carbon dioxide (CO₂) atmospheric measurements from space are required to improve estimates of regional and continental-scale sources and sinks of CO₂. Modeling of a space-based 2-µm, high-pulse-energy, triple-pulse, direct-detection Integrated Path Differential Absorption (IPDA) lidar was conducted to demonstrate CO₂ measurement capability and to evaluate random and systematic errors. Parameters based on recent technology developments in the 2-μm laser and state-of-the-art HgCdTe (MCT) electron-initiated avalanche photodiode (e-APD) detection system were incorporated in this model. Strong absorption features of CO₂ in the 2-µm region, which allows optimum lower tropospheric and near surface measurements, were used to project simultaneous measurements using two independent altitude-dependent weighting functions with the triple-pulse IPDA. Analysis of measurements over a variety of atmospheric and aerosol models using a variety of Earth’s surface target and aerosol loading conditions were conducted. Water vapor (H₂O) influences on CO₂ measurements were assessed, including molecular interference, dry-air estimate and line broadening. Projected performance shows <0.35 ppm precision and <0.3 ppm bias in low-tropospheric weighted measurements related to column CO2 optical depth for the space-based IPDA using 10 second signal averaging over the Railroad Valley (RRV) reference surface under clear and thin clouds conditions.

An improvement in imaging contrast feature of liquid crystal lens with the dopant of multi-walled carbon nanotubes

Hui Li, Fan Pan, Yuntao Wu, Yanduo Zhang, and Xiaolin Xie

Doc ID: 297185 Received 05 Jun 2017; Accepted 13 Jul 2017; Posted 14 Jul 2017  View: PDF

Abstract: An effective method to fabricate a high contrast imaging liquid crystal (LC) lens with a relatively fast response time is proposed. This electrically tunable-focus LC lens is doped with multi-walled carbon nanotubes (MWCNTs) and has a high resistance layer. A grinding method is utilized to lower agglomeration of doping MWCNTs. With respect to the high resistance layer, it can make maximum use of doped nano particles to behave high quality lens character. The principles of improvement in electro-optical properties are discussed. The experimental results show that the proposed LC lens are effectively improved. The LC lens has greatly potential in compact imaging system.

Diffuse optical localization of blood vessels and 3Dprinting for guiding oral surgery

Brian Bentz, Timothy Wu, Vaibhav Gaind, and Kevin Webb

Doc ID: 296207 Received 17 May 2017; Accepted 13 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: Diffuse optical imaging through centimeters of tissue has emerged as a powerful tool in biomedicalresearch. However, applications in the operating theater have been limited in part due to data setrequirements and the computational burden. We present an approach that uses a small number of opticalsource-detector pairs that allows for the fast localization of arteries in the roof of the mouth and hasthe potential to reduce complications during oral surgery. The arteries are modeled as multiple pointabsorbers, allowing localization of their complex shapes. The method is demonstrated using a printedtissue-simulating mouth phantom. Furthermore, we use the extracted position information to fabricate acustom surgical guide using 3D printing that could protect the arteries during surgery.

Temperature sensitivity enhancement of the platinum nanoparticles coated long period fiber gratings fabricated by femtosecond laser

xinran Dong, zheng xie, Chu Zhou, Kai Yin, luo zhi, and Ji'an Duan

Doc ID: 296528 Received 22 May 2017; Accepted 13 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: The temperature sensing performance of long period fiber gratings (LPFGs) written byfemtosecond laser pulses coated with platinum nanoparticles (PtNPs) is proposed anddemonstrated. It is found that the PtNPs increases the wavelength sensitivity of LPFGsignificantly compared with the bare LPFG. The temperature sensitivities of the bare LPFGfor three dips corresponding to 1438nm, 1485nm and 1585nm are 74.04pm/℃, 77. pm/℃ and 86.26 pm/℃, respectively, when the temperature changes from 10℃ to 500℃,whereas the corresponding sensitivities of PtNPs coated LPFG are up to 90.58 pm/℃, 93.51pm/℃ and 103.43 pm/℃, respectively. Moreover, the PtNPs coated LPFG shows betterwavelength repeatability. A small wavelength hysteresis of ~ 0.5 nm is observed when thetemperature is less than 300℃.

Optical, magnetic, and charge-carriers transport properties of a transition metal: bulk palladium.

William Vargas

Doc ID: 301320 Received 30 Jun 2017; Accepted 13 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: Three parametric models of Drude-Lorentz are used to describe the spectral variation of the dielectric function of bulk Palladium. An improved version of the Acceptance-Probability-Controlled Simulated Annealing method is applied to optimize the values of the parameters involved in the models: high frequency dielectric constant, free electron collision frequency and corresponding relaxation time, oscillation strengths, nominal resonance frequencies, and Lorentzian widths. Normalization of the oscillation strengths allows the introduction of a new parameter in the context of Drude-Lorentz model: the number density ratio, which is the ratio between number density of conduction electrons and number density of metal atoms. Inclusion of this parameter in the optimization procedure allows us to evaluate additional parameters related to the charge-carriers transport: number density of conduction electrons, average effective mass of conduction electrons and holes, Fermi energy and electronic density of states at the Fermi energy, electrical resistivity, intrinsic mean free path of conduction electrons, electronic heat capacity, Hall coefficient, as well as mobilities of conduction electrons and holes. The paramagnetic and diamagnetic susceptibilities are also included as derived parameters. A parametric form of bulk Pd dielectric function, with incorporation of local field effects in the Lorentz contribution, is reported.

Black phosphorus flakes covered microfiber for Q-switched ytterbium doped fiber laser

Ke-Xun Huang, Baole Lu, Diao Li, Xinyuan Qi, Hao-wei Chen, NA Wang, Zengrun Wen, and Jintao Bai

Doc ID: 296137 Received 16 May 2017; Accepted 12 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: We demonstrate a passively Q-switched ytterbium doped fiber laser based on black phosphorus flakes covered microfiber. The BP saturable absorber is fabricated by sandwiching a microfiber between two pieces of polydimethylsiloxane supported BP flakes films, which is prepared by mechanical exfoliation method. In this case the BP flakes can be well protected from the action of air and moisture. By incorporating BP flakes covered microfiber into ytterbium doped ring fiber laser, stable and reliable Q-switched operation at 1064 nm can be realized via interaction between few layers BP flakes and the evanescent field of the laser. The laser allows Q-switched pulse generation with a repetition rate in the range of 26-76 kHz and a pulse duration in the range of 5.5-2.0 μs, by varying the pump power from 38 mW to 100 mW.

Generation of square pulse with ultra-wide tuning range in a passively mode-locked Yb-doped fiber laser

Yafei Cao, Dongfang Jia, Tonghui Liu, Tianxin Yang, Zhaoying Wang, and Chunfeng Ge

Doc ID: 297146 Received 05 Jun 2017; Accepted 12 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: We have experimentally demonstrated square pulse in a passively mode-locked Yb-doped fiber ring laser operating in the dissipative soliton resonance (DSR) region based on nonlinear polarization rotation tech-nique. In our experiment, a 1.5 km long single-mode fiber (SMF) is inserted into the cavity to increase the cavity length. The total cavity is 1501.8 m. With the increase of pump power, the pulse duration can be tuned from 209.8ns to 812.4ns without wave-breaking and the maximum output single pulse ener-gy is 42.34nJ. To the best of our knowledge, this is the widest pulse in any Yb-doped mode-locked fiber laser. Moreover, the relationship between pulse width and cavity length is investigated. When the total cavity length is decreased to 1001.8m and 501.8 m, the tuning range of square pulse is 372.4 ns (from 58.6 ns to 431 ns ) and 138 ns (from 26 ns to164 ns),respectively. And the maximum output single pulse energy is 13.85 nJ and 8.75 nJ, respectively.

Convex relaxation for illumination control of multi-color MIMO VLC with LMMSE detection

Junming Dong, zhang Yan-yu, and zhu yi-jun

Doc ID: 297136 Received 31 May 2017; Accepted 12 Jul 2017; Posted 12 Jul 2017  View: PDF

Abstract: Visible light communications (VLC) using multi-color light-emitting diode (LED) can support simultaneous high speed data rate and high quality lighting. However, since the radiation spectrum of LED has a limited width, spectral overlapping will result in multi-color crosstalk even when optical filters are applied at the receivers. Moreover, since LEDs are used for illumination and wireless data transmission in the meantime, both lighting quality and communication performance must be considered in VLC systems.In this paper, we consider a multiple-input-multiple-output (MIMO) with low-complexity linear minimum mean square error (LMMSE) detection to collaboratively manage the crosstalk by maximizing the minimum signal-to-interference-plus-noise-ratio (SINR) subject to chromaticity constraint based on MacAdam ellipse, luminance constraint and signal range constraint. A sub-optimal convex relaxation is proposed to attack the SINR maximization problem. Extensive simulations indicate that the proposed method provides very efficient solutions and outperforms the conventional wave division multiplexing scheme under the illumination constraint.

Experimental analysis of dynamic north-finding method based on a fiber optic gyroscope

Zhu Zhou, Zhongwei Tan, Xinyue Wang, and Ziyu Wang

Doc ID: 291243 Received 23 Mar 2017; Accepted 12 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: This paper demonstrates the principles of static and dynamic north-finding methods by measuring the projectionof the Earth rotation rate with a fiber optic gyroscope. For a comprehensive comparison of the two methods, theinfluence of close-looped feedback mechanism of a servo motor in turntable is taken into consideration. Thus, weproposed the static and dynamic north-finding experimental implementations according to the different impact ofthe motor jitters and the different seeking time. Experimental results show that the dynamic method can reducethe north-finding bias error and instability by 60.1% and 54.6%, respectively, in the seeking time of 360 sec, whilethe reduce proportion are 81.3% and 82.5% in the seeking time of 120 sec, compared with the static method underthe jittering effect of the turntable. Therefore, the dynamic method is more accurate and robust to the jitteringeffect can be concluded.

Detection and characterization of chemical aerosol using laser trapping single particle Raman

Aimable Kalume, Leonid Beresnev, Joshua Santarpia, and Yongle Pan

Doc ID: 292709 Received 14 Apr 2017; Accepted 12 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: Detection and characterization of the presence of chemical agent aerosols in various complex atmospheric environments is an essential defense mission. Raman spectroscopy has the ability to identify chemical molecules, but there are limited photons detectable from single airborne aerosol particles as they are flowing through a detecting system. In this paper, we report on a single-particle Raman spectrometer system that can measure strong spontaneous, stimulated, and resonance Raman spectral peaks from a single laser-trapped chemical aerosol particle, such as a droplet of the VX nerve agent chemical simulant diethyl phthalate. Using this system, time-resolved Raman spectra and elastic scattered intensities were recorded to monitor the change in chemical properties and size variation of the trapped particle. Such a system supplies a new approach for the detection and characterization of single airborne chemical aerosol particles.

Classification of Morphologically Similar Algae andCyanobacteria Using Mueller Matrix Imaging andConvolutional Neural Networks

Xianpeng Li, Ran Liao, Jialing Zhou, Priscilla Leung, Meng Yan, and Hui Ma

Doc ID: 292862 Received 17 Apr 2017; Accepted 12 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: We present the Mueller matrix imaging system to classify morphologically similar algae based on the convolutionalneural networks (CNNs). The algae and cyanobacteria dataset contains 10463 Mueller matrices from eight speciesof algae and one species of cyanobacteria, belonging to four phyla, the shapes of which are mostly randomlyoriented spheres, ovals, wheels or rods. The CNN serves as an automatic machine with learning ability to help inextracting features from Mueller matrix, and trains a classifier to achieve a 97% classification accuracy. Wecompare the performances in two ways. One way is to compare the performances of five CNNs that differ in thenumber of convolution layers as well as the classical principle component analysis (PCA) plus support vectormachine (SVM) method, the other way is to quantify the differences of scores between full Mueller matrix and thefirst matrix element m11 that does not contain polarization information, under the same conditions. As the resultsshow, deeper CNNs perform better, the best of which outperforms the conventional PCA plus SVM method by19.66% in accuracy, and using full Mueller matrix earns 6.56% increase of accuracy than using m11. Itdemonstrates that the coupling of Mueller matrix imaging and CNN may be a promising and efficient solution forthe automatic classification of morphologically similar algae.

Novel lidar algorithms for atmospheric slant - range visibility, meteorological conditions detection and atmospheric layering measurements

Alexandros Pantazis, Alexandros Papayannis, and Georgios Georgoussis

Doc ID: 292625 Received 11 Apr 2017; Accepted 11 Jul 2017; Posted 11 Jul 2017  View: PDF

Abstract: Visibility at airports has to do in many ways with flight and ground safety. We present a novelmethod and algorithms based on lidar measurements and signal noise subtraction to provideatmospheric layering and estimated visibility values for tower controllers and meteorologists aswell as from pilot’s point of view, according to the International Civil Aviation Organization (ICAO)and World Meteorological Organization (WMO) requirements.

Heat coupled Gaussian continuous-wave double-pass optical parametric oscillator: thermally induced phase mismatching for periodically poled MgO:LiNbO3 crystal

mahbube khabaz, Mohammad Sabaeian, and hamid nadgaran

Doc ID: 294946 Received 02 May 2017; Accepted 11 Jul 2017; Posted 11 Jul 2017  View: PDF

Abstract: In this paper, a model describing the thermal effects on the optical parametric oscillator (OPO) of Gaussian continuous-wave (CW) in double-pass cavities is presented. Eight equations including forward and backward nonlinear waves, heat, and thermally induced phase mismatching (TIPM) equations were coupled and solved simultaneously to investigate the effect of heat generation on the OPO’s efficiency. The model was applied for a periodically-poled MgO:LiNbO3 crystal with an excellent agreement with experimental data. The numerical calculations have been carried out by a home-made code written in Intel FORTRAN which is used a finite difference method.

Simple light emitting electrochemical cell using reduced graphene oxide and a ruthenium (II) complex

Harry Rivera, Johannes Zimmermann, Nils Jügensen, Gerardo Hernandez-Sosa, and Maria Quintana

Doc ID: 295990 Received 15 May 2017; Accepted 11 Jul 2017; Posted 12 Jul 2017  View: PDF

Abstract: We report the use of conducting substrates from reduced graphene oxide (rGO) applied in light emitting electrochemical cells (LECs) in which we used an electroluminescent polymer (EP) as a light emitting layer. The emitting layer was conformed by an organic metal complex of tris (2, 2′-bipyridine) ruthenium (II) linked to the sodium tetrafluoroborate anion ([Ru (bpy)3]+2)(BF4)-1. The luminance generated from the electroluminescent device was 6.89 Cd/m2 when applying a voltage of 13.48 V and current of 10.19 mA. The luminance of this device was maintained constant for 36.84 min. The prolonged life time of the electrochemical device was achieved by depositing an rGO thin layer with a 161.3 nm thickness inside the LEC structure

Performance analysis of PPM-FSO communication system with APD receiver over atmospheric turbulence channels with aperture averaging

Huihua Fu, Ping Wang, Tao Liu, Tian Cao, Lixin Guo, and Jiao Qin

Doc ID: 296890 Received 30 May 2017; Accepted 10 Jul 2017; Posted 11 Jul 2017  View: PDF

Abstract: The average bit-error rate (ABER) performance of an avalanche photodiode (APD)-based pulse-position modulation (PPM) free-space optical (FSO) communication system is investigated considering aperture averaging effect. The approximate ABER expression is theoretically derived in terms of M and exponentiated Weibull (EW) distributions under weak-to-strong turbulent atmosphere conditions with a binary PPM (BPPM) scheme. Union bound and Hermite polynomial are then considered to estimate the performance of M-ary PPM FSO systems. The system performance is analyzed with the aperture sizes, turbulence strengths, receiver temperatures, and average photon counts taken into account. The results show that an optimal average APD gain, which is effected by receiver temperature, can be chosen to minimize the ABER value. And the impact of aperture averaging on the system performance over M distribution is not so apparent as that over EW distribution for different temperatures, turbulent strengths and average photon counts. In addition, the present APD-based system can offer better ABER performance than that of P-i-N (PIN)-based PPM system over both EW and M fading channels at 300 and 500 K. This work is beneficial to the FSO system design.

Measurement of picometer-scale mirror dynamics

Babak Saif, David Chaney, Perry Greenfield, Marcel Bluth, Kyle Van Gorkom, Koby Smith, Joshua Bluth, Lee Feinberg, James Wyant, Michael North Morris, and Ritva Keski-Kuha

Doc ID: 294954 Received 15 May 2017; Accepted 10 Jul 2017; Posted 12 Jul 2017  View: PDF

Abstract: A High Speed Interferometer has been designed and built to measure the dynamics of the James Webb Space Telescope primary mirror system currently under testing. This interferometer is capable of tracking large absolute motion (i.e., piston) of the mirror’s entire surface over orders of magnitudes of wavelengths displacement. Preliminary tests have shown it to be capable of measuring dynamic effects on the level of tens of picometers reliably. This paper reports the details of test setup to do so, the data system used to collect and process the data, and the algorithms to distill the dynamics motions detected. The results that were obtained are presented and followed by a discussion of the conclusions and potential applications of this measurement technique.

Centroid estimation for Shack-Hartmann wavefront sensor based on stream processing

Fanpeng Kong, Manuel Cegarra Polo, and Andrew Lambert

Doc ID: 294967 Received 02 May 2017; Accepted 10 Jul 2017; Posted 11 Jul 2017  View: PDF

Abstract: Using center of gravity to estimate the centroid of the spot in Shack-Hartmann wavefront sensor, the mea- surement corrupts with photon and detector noise. Parameters like window size often requires careful optimization to balance the noise error, dynamic range and linearity of the response coefficient under different photon flux. It also needs to be substituted by correlation method for extended sources. We propose a centroid estimator based on stream processing, where the center of gravity calculation window floats with the incoming pixel from the detector. In comparison with conventional methods, we show that the proposed estimator simplifies the choice of optimized parameters, provides a unit linear coefficient response and reduces the influence of background and noise. It is shown that the stream-based centroid estimator also works well for limited extended sources. A hardware implementation of the proposed estimator is discussed.

Convolution and Fourier transform based reconstructors for pyramid wavefront sensor

Iuliia Shatokhina and Ronny Ramlau

Doc ID: 291364 Received 24 Mar 2017; Accepted 10 Jul 2017; Posted 11 Jul 2017  View: PDF

Abstract: In this paper we present two novel algorithms for wavefront reconstruction from pyramid-type wavefront sensors data. An overview of the current state-of-the-art in the application of pyramid-type wavefront sensors shows that the novel algorithms can be applied in various scientific fields such as astronomy, ophthalmology, and microscopy. Assuming a computationally very challenging setting corresponding to the extreme adaptive optics on the European Extremely Large Telescope, we present the results of the performed end-to-end simulations and compare the achieved AO correction quality (in terms of the long exposure Strehl ratio) to other methods like MVM and P-CuReD. Also, we provide a comparison in terms of applicability, computational complexity and closed loop performance, of our novel algorithms to other methods existing for this type of sensor.

Optical properties and electronic transitions of ZnO, α-Fe₂O₃, CeO₂ and Sm₂O₃ in the ultraviolet and extreme ultraviolet

Nicolas Pauly, Francisco Yubero, Juan Pedro Espinós, and Sven Tougaard

Doc ID: 285063 Received 18 Jan 2017; Accepted 10 Jul 2017; Posted 20 Jul 2017  View: PDF

Abstract: Optical properties and electronic transitions of four oxides, namely ZnO, α-Fe₂O₃, CeO₂ and Sm₂O₃, are determined in the ultraviolet and extreme ultraviolet by Reflection Electron Energy Loss Spectroscopy using primary electron energies in the range 0.3-2.0 keV. This technique allows the evaluation of the optical response in these ultraviolet spectral regions of a thin layer of material without any special sample preparation procedure, and the analysis is straightforward. It is performed within the dielectric response theory by means of the QUEELS-ε(k,ω)-REELS software developed by Tougaard and Yubero [Surf. Interface Anal. 2004; 36, 824]. The method consists basically in the fitting of experimentally determined single scattering electron energy loss cross sections with a parametric energy loss function of the corresponding material, to the one calculated within a dielectric response formalism. The obtained refractive index and extinction coefficients, as well as the identified electronic transitions are compared, when available, with previously published results.

Optimization of multibeam pumped optical parametric amplifier

S. Frolov and V. Trunov

Doc ID: 292597 Received 24 Apr 2017; Accepted 09 Jul 2017; Posted 11 Jul 2017  View: PDF

Abstract: The results of numerical simulation of the output amplifier cascade of a powerful laser system based on the parametric amplification of femtosecond pulses in an LBO crystal with multiple beams pumping are presented. The improved technique for choosing pump beam angles with minimal parasitic amplification is presented. Differences of carrier-resolving vs. envelope simulations are discussed. Results for pulse energy, duration and fraction of parasitic energy are presented. It has been established that with an increase in the number of pump beams up to 11 beams, the duration of the amplified pulse increases insignificantly from 20 to 21 fs in the case of incoherent pumping beams and increases to 26 fs in the case of coherent ones. At the same time, the amplification efficiency decreases from to 21% in the first case and drops to 10% in the second case. Influence of small-scale self-focusing of pump field interference pattern on peak intensity is discussed.

Design of smooth freeform illumination system forpoint light source based on polar-type optimaltransport mapping

mao xianglong, songbo xu, Xinrong Hu, and yongjun xie

Doc ID: 296239 Received 18 May 2017; Accepted 09 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: A design method is proposed to generate smooth freeform illumination optics for a point light source based on theL2 optimal transport (LOT) mapping. In this method, the LOT mapping between an assumed circular planar sourceand a prescribed target is firstly obtained by solving a polar-type LOT problem. Then, the mapping calculated forthe circular source is applied for a point light source. Finally, the freeform optical surface is generated by ageometric construction method to realize the ray mapping. As examples, a series of smooth-surface freeform lensesare designed for a point light source to form uniform and complex illumination patterns on rectangular targets.The ray-tracing results show that all the designs achieve excellent performance with the light utilization efficiencyη over 0.87 (Fresnel loss considered) and the relative standard deviation RSD of the simulated illuminationdistribution less than 0.051 simultaneously.

Active Underwater Descattering and Image Recovery

Pingli Han, Fei Liu, kui yang, Jinyu Ma, Jianjun Li, and Xiaopeng Shao

Doc ID: 296266 Received 19 May 2017; Accepted 09 Jul 2017; Posted 11 Jul 2017  View: PDF

Abstract: Underwater imaging is a promising but challenging topic due to the scattering particles in water which result in serious light attenuation. Therefore, underwater images suffer from low-contrast and low-resolution issues. In this study, in order to recover high-quality underwater images, the Point Spread Functions (PSF) are estimated by a slant-edge method. The experiment modulates the illumination source to deal with backscattering and the imager to take two images in orthogonally polarized states. This imaging method benefits to the satisfactory edge extraction. The PSF estimation is performed based on the extracted slant edge to enable recovery of image. In addition, the Modulation Transfer Function (MTF) is introduced to evaluate the resolution variation with the spatial frequencies. It manifests considerable resolution enhancement in the recovered images. Moreover, the proposed underwater image recovery method also reduces the effect from the scattering as an effective compensation to the polarization imaging approach.

Probing methane in air with a mid-infrared frequency comb source

Feng Zhu, Jinbao xia, Aysenur Bicer, James Bounds, Alexandre Kolomenskii, James Strohaber, Lewis Johnson, Mahmood Amani, and Hans Schuessler

Doc ID: 286783 Received 27 Feb 2017; Accepted 09 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: We employed a mid-infrared frequency comb source for methane detection in ambient air. The transmitted spectra over a bandwidth of about 500 nm were recorded with an optical spectrum analyzer under various experimental conditions of different path lengths. The normalized absorption spectra were compared and fitted with simulations, yielding quantitative values of concentrations of methane and water vapor in the ambient air. This approach provides a broad spectral range, a large dynamic range, high sensitivity and accurate calibration. The performed analysis of the residuals shows that an excellent agreement between the measured and calculated spectral profiles was obtained.

The Lorenz curve of a light beam: evaluating beam quality from a new perspective

Miguel Porras, Isabel Gonzalo, and M. Ahmir Malik

Doc ID: 292985 Received 17 Apr 2017; Accepted 09 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: We introduce a novel approach for the characterization of the quality of a laser beam that is not based on particular criteria for beam width definition. The Lorenz curve of a light beam is a sophisticated version of the so-called power-in-the-bucket curve, formed by the partial sums of discretized joint intensity distribution in the near and far fields sorted in decreasing order. According to majorization theory, a higher Lorenz curve implies that all measures of spreading in phase space, and, in particular, all R\'enyi (and Shannon) entropy-based measures of the beam width products in near and far fields, are unanimously smaller, providing a strong assessment of a better beam quality. Two beams whose Lorenz curves intersect can only be considered of relatively better or lower quality according to specific criteria, which can be inferred from the plot of the respective Lorenz curves.

In situ detection of water quality contamination events based on signal complexity analysis using online UV-VIS spectral sensor

Pingjie Huang, Ke Wang, Dibo Hou, JIAN ZHANG, JIE YU, and Guangxin Zhang

Doc ID: 296373 Received 26 May 2017; Accepted 08 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: The contaminant detection in water distribution systems is essential to protect public health from potential harmful compounds resulting from accidental spills or intentional releases. As a noninvasive optical technique, ultraviolet-visible spectroscopy is investigated for detecting contamination events. However, current methods for event detection exits the shortcomings of noise susceptibility. In this paper, a new method that has less sensitivity on noise was proposed to detect water quality contamination events by analyzing the complexity of the UV-vis spectrum series. The proposed method applied approximate entropy (ApEn) to measure spectrum signals' complexity, which made a distinction between normal and abnormal signals. And the impact of noise was attenuated with the help of ApEn's insensitive to signal disturbance. This method was tested on a real water distribution system data set with various concentration simulation events. Results from the experiment and analysis show that the proposed method has a good performance on noise tolerance and provides a better detection result compared with autoregressive (AR) model and sequential probability ratio test (SPRT).

Development of a spatially dispersed short-coherence interferometry sensor using diffraction grating orders

Mothana Hassan

Doc ID: 297100 Received 01 Jun 2017; Accepted 07 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: Modern manufacturing processes can achieve good throughput by requiring that manufactured products be screened by better quality control exercised at a quicker rate. This trend in the quality control of manufactured products increases the need for process-oriented precision metrology capable of performing faster inspections and yielding valuable feedback to the manufacturing system. This paper presents a spatially dispersed short-coherence interferometry sensor using diffraction orders of the zeroth and first-order for a diffraction grating has been introduced as a new compact system configuration for surface profile measurement. In this modified design, the diffraction grating acts as the beam splitter/combiner. Diffractions for the zeroth and first-orders are represented by the reference and measurement arms, respectively, of a Michelson interferometer, which reduces the optical path length. This innovative design has been proven effective for determining the step-height repeatability in the sensor range from 27 nm to 22 nm for profiles spanning the step-heights of the tested specimens.

Sub-diffraction limit laser ablation via multiple exposures using a digital micromirror device

Daniel Heath, James Grant-Jacob, Matthias Feinäugle, Benjamin Mills, and Robert Eason

Doc ID: 297578 Received 07 Jun 2017; Accepted 07 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: We present the use of digital micromirror devices as variable illumination masks for pitch-splitting multiple exposures to laser machine the surfaces of materials. Ultrafast laser pulses of length 150 fs and 800 nm central wavelength were used for the sequential machining of contiguous patterns on the surface of samples in order to build up complex structures with sub-diffraction limit features. Machined patterns of tens to hundreds of microns in lateral dimensions with feature separations as low as 270 nm were produced in electroless nickel on an optical setup diffraction-limited to 727 nm, showing a reduction factor below the Abbe diffraction limit of ~2.7x. This was compared to similar patterns in a photoresist optimised for two-photon absorption, which showed a reduction factor of only 2x, demonstrating that multiple exposures via ablation can produce a greater resolution enhancement than via two-photon polymerisation.

N-isopropylacrylamide-based photopolymer for holographic recording of thermosensitive transmission and reflection gratings

Tatsiana Mikulchyk, Suzanne Martin, and Izabela Naydenova

Doc ID: 295431 Received 09 May 2017; Accepted 07 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: In recent years, functionalized photopolymer systems capable of holographic recording are in great demand due to their potential use in the development of holographic sensors. This work presents a newly developed N-isopropylacrylamide(NIPA)-based photopolymer for holographic recording in reflection and transmission modes. The optimized composition of the material is found to reach refractive index modulation of up to 5 × 10-³ and 1.6 × 10-³ after recording in transmission and reflection mode, respectively. In addition to fulfilling the requirements for holographic recording materials, the NIPA-based photopolymer is sensitive to temperature and has lower toxicity than acrylamide-based photopolymers. Possible application of the NIPA-based photopolymer in the development of a holographic temperature sensor is discussed.

Visualization and label-free quantification of microfluidic mixing using quantitative phase imaging

GwangSik Park, Dongsik Han, GwangSu Kim, Seungwoo Shin, Kyoohyun Kim, Je-Kyun Park, and YongKeun Park

Doc ID: 296024 Received 15 May 2017; Accepted 07 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: Microfluidic mixing plays a key role in various fields, including biomedicine and chemical engineering. To date, although various approaches for imaging microfluidic mixing have been proposed, they provide only quantitative imaging capability and require for exogenous labeling agents. Quantitative phase imaging techniques, however, circumvent these problems and offer label-free quantitative information about concentration maps of microfluidic mixing. We present the quantitative phase imaging of microfluidic mixing in various types of PDMS microfluidic channels with different geometries; the feasibility of the present method was validated by comparing it with the results obtained by theoretical calculation based on Fick’s law.

InP-based persudomorphic InAs/InGaAs triangular quantum well lasers with bismuth surfactant

Wanyan Ji, Y G, Yonggang Zhang, Yingjie Ma, x c, Qian Gong, B D, and Yanhui Shi

Doc ID: 296517 Received 22 May 2017; Accepted 07 Jul 2017; Posted 07 Jul 2017  View: PDF

Abstract: An InP-based 2.1 µm InAs/In0.53Ga0.47As triangular quantum well laser grown with Bi surfactant has shown improved performance in comparison to the device with the same structure but grown without Bi surfactant. Under continuous-wave driving operation, the output light power is increased from 32.6 to 37.5 mW at the same injecting current of 850 mA at 200 K. The external differential and internal quantum efficiencies for the laser with Bi surfactant are 18.4% and 41%, respectively, which are correspondingly higher than 13.1% and 31% for the reference device. Furthermore, a decreased internal loss from 20.9 to 17.6 cm-1 for the Bi surfactant laser is also observed. These results suggest that Bi surfactant is promising for further enhancing performances of strained quantum well laser diodes.

Breaking camouflage and detecting targets requireoptic flow and image structure information

Jing Pan, Ned Bingham, Chang Chen, and Geoffrey Bingham

Doc ID: 285570 Received 24 Jan 2017; Accepted 07 Jul 2017; Posted 10 Jul 2017  View: PDF

Abstract: Use of motion to break camouflage extends back to the Cambrian [1]. We investigated the ability to break camouflage and continueto see camouflaged targets after motion stops. This is crucial for the survival of hunting predators. With camouflage, visual targetsand distracters cannot be distinguished using only static image structure (i.e., appearance). Motion generates another source ofoptical information, optic flow, which breaks camouflage and specifies target locations. Optic flow calibrates image structure inrespect to spatial relations among targets and distracters and calibrated image structure makes previously camouflaged targetsperceptible in a temporally stable fashion after motion stops. We investigated this proposal using laboratory experiments andcompared how many camouflaged targets were identified either with optic flow information alone or with combined optic flow andimage structure information. Our results show that the combination of motion-generated optic flow and target-projected imagestructure information yielded efficient and stable perception of camouflaged targets.

Modeling the Focusing Efficiency of Lobster-Eye Optics for Image Shifting Depending on the Soft X-Ray Wavelength

Luning Su, Wei Li, Mingxuan Wu, Yun Su, Chongling Guo, NingJuan Ruan, Bingxin Yang, and Feng Yan

Doc ID: 291108 Received 24 Mar 2017; Accepted 06 Jul 2017; Posted 07 Jul 2017  View: PDF

Abstract: Lobster-eye optics is widely applied to space X-ray detection missions and X-ray security check for its wide field of view and low weight. This paper presents a theoretical model to obtain spatial distribution of focusing efficiency based on lobster-eye optics in soft X-ray wavelength. The calculations reveal the competition mechanism of contribution to the focusing efficiency between the geometrical parameters of lobster-eye optics and the reflectivity of the Iridium film. In addition, the focusing efficiency image depending on X-ray wavelengths further explains the influence of different geometrical parameters of lobster-eye optics and different soft X-ray wavelengths on focusing efficiency. These results could be beneficial to optimize parameters of lobster-eye optics in order to realize maximum focusing efficiency.

Detecting wave-front amplitude and phase using linear Phase Diversity

Zhang Dong, Shuyan Xu, Liu nan, and Xiaoyu Wang

Doc ID: 294626 Received 26 Apr 2017; Accepted 05 Jul 2017; Posted 06 Jul 2017  View: PDF

Abstract: We propose a simplified phase diversity method based on the first-order Taylor expansion of the Optical TransferFunction (OTF) as the light intensity on the pupil plane is not uniform but presents Gaussian distribution. Byextending the Zernike polynomial term to the complex field, we regard the distribution of the light intensity as theimaginary part of the phase which can be solved together with the phase aberration (the real part of the phase).The approximation of OTF using first-order Taylor expansion can simplify the relationship between the phase andOTF to linear relation, so that the aberration can be quickly solved. We present an experiment that validates theadvantage of our method. The result shows that the modified method has a higher accuracy with less timecompared to traditional PD algorithm, and can acquire the distribution of the light on the pupil plane.

Compact polarization-based dual-view panoramic lens

Yujie Luo, Xiao Huang, Jian Bai, and Rongguang Liang

Doc ID: 296356 Received 22 May 2017; Accepted 05 Jul 2017; Posted 06 Jul 2017  View: PDF

Abstract: Panoramic annular lens (PAL) is one type of special optical system, which can transform the cylindrical side view onto a planar annular image. We propose a compact polarization-based dual-view panoramic lens to solve the two major limitations of conventional PAL structure: large front annular lens and lack of forward view. Dual-view imaging capability, which is highly needed for some applications, is achieved by using polarization technique. The diameter ratio of the proposed front PAL lens and the sensor is reduced to less than 1.5, while it is larger than 2.5 for traditional PAL systems, expanding its applications in space-confined environment.

Astrometric distortion calibration of a portable refractor

Donald Bruns and Corey Bruns

Doc ID: 297193 Received 01 Jun 2017; Accepted 05 Jul 2017; Posted 06 Jul 2017  View: PDF

Abstract: A compact refractor simplifies imaging stars during a total solar eclipse from remote, temporary locations. To achieve astrometric precision, cubic distortion terms were measured using hundreds of night-time images. A detailed procedure is presented here, along with an example from a portable telescope. The results show that precisions down to the 20 milli-arcsec level are possible with commercial equipment.

Design and characterization of an integrated surfaceion trap and micromirror optical cavity

Andre Van Rynbach, George Schwartz, Robert Spivey, James Joseph, Geert Vrijsen, and Jungsang Kim

Doc ID: 293425 Received 10 May 2017; Accepted 05 Jul 2017; Posted 13 Jul 2017  View: PDF

Abstract: We have fabricated and characterized laser ablated micromirrors on fused silica substrates for constructingstable Fabry-Perot optical cavities. We highlight several design features which allow these cavitiesto have lengths in the 250-300 mm range and be integrated directly with surface ion traps. We present amethod to calculate the optical mode shape and losses of these micromirror cavities as a function of thecavity length and mirror shape, and confirm that our simulation model is in good agreement with experimentalmeasurements of the intra-cavity optical mode at a test wavelength of 780 nm. We have designedand tested a mechanical setup for dampening vibrations and stabilizing the cavity length, and explore applicationsfor these cavities as efficient single photon sources when combined with trapped 171Yb+ ions.

General Method of Extreme Surfaces for Geometry Optimization of the Linear Electro-Optic Effect on an Example of LiNbO3:MgO Crystals

Anatoliy Andrushchak, Oleh Buryy, NAZARIY ANDRUSHCHAK, Zenon Hotra, Orest Sushynskyi, Ghanshyam Singh, Vijay Janyani, and Iwan Kityk

Doc ID: 290996 Received 22 Mar 2017; Accepted 04 Jul 2017; Posted 05 Jul 2017  View: PDF

Abstract: The general method for determining the global maximum of linear electro-optic effect in crystalline materials based on the construction and analysis of extreme surfaces obtained as a result of optimization procedure is proposed. The electrically induced optical pathlength change for ordinary and extraordinary waves as well as the optical path difference for orthogonal polarized waves were used as the objective functions in the optimization. The objective functions were determined for unit of electric field and crystal thickness in the light pass direction. On the example of LiNbO3:MgO it is shown that maximal achievable given values of the optical path length change (global maxima) for the ordinary and extraordinary waves are 119 pm/V and 277 pm/V, respectively. The global maximum of the optical path difference for orthogonal polarized waves is 269 pm/V (for 632.8 nm wavelength and at room temperature). These global maxima are exceed in ~1.5, 1.7 and 2.3 times the respective maximum values on direct cuts crystals of LiNbO3:MgO, and in ~5, 9 or 11 % larger from the global maxima for undoped LiNbO3 crystal. This ensures a possibility to increase the energy efficiency in ~2.9 or 5.3 times in case of using of LiNbO3:MgO crystals with optimal cuts as sensitive elements of electro-optic devices.

Circular Dichroism effect in a double layer dolmen array nanostructure

yao liu and xiao Shan

Doc ID: 292951 Received 21 Apr 2017; Accepted 04 Jul 2017; Posted 05 Jul 2017  View: PDF

Abstract: Chiral plasmonic nanostructures have been studied widely in past years and have various applications in biological sensing, negative refractive index and analytical chemistry. Dolmens is also a common used nanostructure in many recent proposed researches. By putting dolmens in different directions and formed a Double Layer Dolmen Array (DLDA), a new nanostructure with good Circular Dichroism(CD) effect is designed in this paper. Up to the maximum of 0.6 of CD effect we get through numerical simulation. In all three resonance wavelengths of CD effect, magnetic dipole resonance appears in two of them and contributes to the origin of strong CD effect. In these different coupling modes, the strongest locating at the largest wavelength is the result of a big magnetic dipolar resonance generated by circulation current in two layers of dolmen together, and the second strongest CD effect is caused by individual magnetic dipolar resonance in opposite direction located in each layer. At the weakest one, the circulation current disappears and only a regular electric dipolar resonance appears. This simulation result shows that magnetic dipolar resonance of plasmonic nanostructure could create a strong CD effect, and much more effectively in DLDA we proposed. The results can help us in designing novel chiral optical nanostructures and provide usages in applications in the interactions between photons and electrons.

Analytic conic constants to reduce the spherical aberration of single lens used in collimated light

Maximino Avendaño Alejo, Edwin Román-Hernández, Luis Castañeda, and Victor Moreno-Oliva

Doc ID: 295102 Received 04 May 2017; Accepted 01 Jul 2017; Posted 03 Jul 2017  View: PDF

Abstract: We study the formation of caustic surfaces produced by conic lenses, considering a plane wavefront prop- agating parallel to the optical axis. The shape of the caustic can be modified by changing the parameters of the lens in such a way that if we are able to vanish the caustic, the optical system produces sharpest images diffraction-limited. Alternatively caustic surfaces having a large area can be applied to design non-imaging optical systems, with potential applications such as diffusers of light for illumination or solar concentrators. Here, we provide analytic equations for the conic constants, principal surfaces, and caustic surfaces and also approximations at third and fifth order formed by conic lenses, in order to reduce the spherical aberration at these orders.

Optical Turbulence in Confined media : Part II, First results using the INTENSE instrument

Flavien Blary, Julien Chabé, Aziz Ziad, Julien Borgnino, Yan FANTEI-CAUJOLLE, Arnaud Liotard, and Frederic Falzon

Doc ID: 280533 Received 14 Nov 2016; Accepted 29 Jun 2017; Posted 29 Jun 2017  View: PDF

Abstract: Optical system performances can be affected by local optical turbulence created by its surrounding environment (telescope dome, clean room, atmospheric layer). This paper follows a previous one introducing the INTENSE (Indoor TurbulENce SEnsor) instrument for optical turbulence characterization in local area by exploitation of laser beams Angle-of-Arrival fluctuations. After a brief summary of the theoretical background, we present in this part results obtained by the INTENSE instrument in various optical integration testing clean rooms and telescope domes, each with specific air behavior conditions.

Lensless Photography with only an image sensor

Ganghun Kim, Kyle Issacson, Rajesh Menon, and Rajesh Menon

Doc ID: 287691 Received 08 Mar 2017; Accepted 29 Jun 2017; Posted 11 Jul 2017  View: PDF

Abstract: Photography usually requires optics in conjunction with a recording device (an image sensor). Eliminating the optics could lead to new form factors for cameras. Here, we report a simple demonstration of imaging using a bare CMOS sensor that utilizes computation. The technique relies on the space variant point-spread functions resulting from the interaction of a point source in the field of view with the image sensor. These space-variant point-spread functions are combined with a reconstruction algorithm in order to image simple objects displayed on a discrete LED array as well as on an LCD screen. We extended the approach to video imaging at the native frame rate of the sensor. Finally, we performed experiments to analyze the parametric impact of the object distance. Improving the sensor designs and reconstruction algorithms can lead to useful cameras without optics.

Uncertainty budgets for liquid waveguide capillary cell(LWCC) CDOM absorption measurements

Ina Lefering, Rüdiger Röttgers, Christian Utschig, and David McKee

Doc ID: 295603 Received 09 May 2017; Accepted 28 Jun 2017; Posted 29 Jun 2017  View: PDF

Abstract: Long pathlength liquid waveguide capillary cell (LWCC) systems using simple spectrometers to determine thespectral absorption by coloured dissolved organic matter (CDOM) have previously been shown to have bettermeasurement sensitivity compared to high-end spectrophotometers using 10 cm cuvettes. Information on themagnitude of measurement uncertainties for LWCC systems, however, has remained scarce. Cross-comparison ofthree different LWCC systems with three different pathlengths (50 cm, 100 cm, and 250 cm) and two differentcladding materials enabled quantification of measurement precision and accuracy, revealing strong wavelengthdependency in both parameters. Stable pumping of the sample through the capillary cell was found to improvemeasurement precision over measurements made with the sample kept stationary. Results from the 50 cm and 100cm LWCC systems, with higher refractive index cladding, showed systematic artefacts including small butunphysical negative offsets and high frequency spectral perturbations due to limited performance of the salinitycorrection. In comparison, the newer 250 cm LWCC with lower refractive index cladding returned small positiveoffsets that may be physically correct. After null-correction of measurements at 700 nm, overall agreement ofCDOM absorption data at 440 nm was found to be within 5% RMS%E.


Ying Zhong Tian, Huijuan HU, Haoyang CUI, Shouchen YANG, Ji QI, Zhiming XU, and Long Li

Doc ID: 290341 Received 24 Mar 2017; Accepted 22 Jun 2017; Posted 22 Jun 2017  View: PDF

Abstract: Optical microscopy enables the observation of highly magnified objects and material structures on micro surfaces, however with the weakness that it can only acquire 2D images. In order to observe areal features more accurately and intuitively, 3D surface micro topography recovery is applied to form a 3D surface model of an object from its 2D image sequence. In the 3D reconstruction of the focus evaluation operator, there are gray variance operator, grayscale differenceabsolute sum operator, Roberts gradient operator, Tenengrad gradient operator, improved Laplace operator and so on.There are two problems with these operators: one is that there is no difference between (x, y) and the gray scale of the pixel in the diagonal direction in the field.The second is that the window size of the focus evaluation operator is fixed, such as 3×3, 5×5, etc.,the size of the window for each pixel in the image is the same, and the small window may not cover enough field information, but also vulnerable to noise, large windows cover more information, but may cause a smooth phenomenon, affecting the accuracy of the model, and different pixels around the field of pixel color difference is different, the size of the window is not the same.Therefore, this paper proposes a modified omnidirectional Laplacian operator with adaptive window, which can automatically adjust the size of the window according to the color difference within the window, and also takes into account the pixels on the diagonal. In addition, very comprehensive verification experiments are conducted to prove the conclusions.

Coded Aperture Design in Compressive Spectral Imaging Based on Side Information

Laura Galvis Carreno, Daniel Lau, Xu Ma, Henry Arguello, and Gonzalo Arce

Doc ID: 296472 Received 23 May 2017; Accepted 19 Jun 2017; Posted 10 Jul 2017  View: PDF

Abstract: Coded aperture compressive spectral imagers (CSI) sense a three-dimensional data cube by using twodimensionalprojections of the coded and spectrally dispersed input image. Recently, it has been shownthat combining spectral images acquired from a CSI sensor and a complementary sensor leads to substantialimprovement in the quality of the fused image. To maximally exploit the benefits of the complementaryinformation, the spatial structure of the coded apertures must be optimized inasmuch as thesestructures determine the sensing matrix properties and accordingly the quality of the reconstructed images.This paper proposes a method to use side information from an RGB sensor to design the codedaperture patterns of a CSI imager, such that more detailed spatial images and wavelength profiles can bereconstructed. The side information is used as input of an edge detection algorithm to approximate a versionof the edges of the spectral images. The coded apertures are designed to follow the spatial structuredetermined by the estimated spectral edges such that the high frequencies are promoted, leading to moredetailed reconstructed spectral images. Simulations and experimental results indicate that when comparedwith random coded aperture structures, the designed coded apertures based on side informationobtain up to 3dB improvement in the quality of the reconstructed images.

Fast lithography aerial image calculation method based on machine learning

Xu Ma, Xuejiao Zhao, Qiang Wang, Yanqiu Li, Shengjie Zhao, and Lu Zhang

Doc ID: 290453 Received 14 Mar 2017; Accepted 10 Jun 2017; Posted 11 Jul 2017  View: PDF

Abstract: Aerial image calculation for thick masks is an indispensable but time-consuming step in most lithography simulations. This paper develops a fast thick-mask aerial image calculation method based on machine learning for partially coherent lithography systems. First, some sparse sampling points are chosen from the source plane to represent the partially coherent illumination. Then, the training libraries of thick-mask diffraction near-fields are built up for all sampling points based on a set of representative mask features. For an arbitrary thick mask, we calculate its aerial image using the nonparametric kernel regression technique and the pre-calculated training libraries. Subsequently, a post-processing method is applied to compensate for the estimation error and improve the computational accuracy. In addition, this paper also studies the impacts of several key factors on the accuracy and efficiency of the proposed method. Finally, the proposed method is verified by the simulations at 45nm and 14nm technology nodes.

Monitoring stress changes in carbon fiber reinforced polymer composites with GHz radiation

Peter Schemmel and Andrew Moore

Doc ID: 292340 Received 12 Apr 2017; Accepted 16 May 2017; Posted 17 May 2017  View: PDF

Abstract: We performed proof of principle experiments to demonstrate that the reflected power of GHz illumination from the surface of carbon fiber reinforced polymer (CFRP) composites is linearly related to the stress in the material. We introduce a stress coefficient to describe the change in normalized power with applied stress, because the effect is attributed partially to changes in the refractive index of the effective medium comprising the carbon fibers in the polymer matrix. The stress coefficient was -0.549 ± 0.134 /GPa for 3 mm thick samples, and -0.154 ± 0.024 /GPa for 1 mm thick samples, both linear up to the measurement limits of 40 MPa and 100 MPA respectively. This technique opens up the possibility of non-destructive evaluation of stresses in CFRP components for quality assurance in manufacturing settings as well as structural health monitoring of in-service aerospace and automotive parts.

Dependence of depth of focus on spherical aberration of optical systems

Antonin Miks and Jiri Novak

Doc ID: 267338 Received 31 May 2016; Accepted 05 Jul 2016; Posted 06 Jul 2016  View: PDF

Abstract: This paper presents a theoretical analysis and computation of aberration coefficients of the third and fifth order of transverse spherical aberration of an optical system, which generates a ray bundle with a diameter of a geometric-optical circle of confusion smaller than a predetermined limit value. Equations were derived for the calculation of aberration coefficients of an optical system, which satisfy given conditions, and for the determination of the maximum possible depth of focus for given conditions.

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