Abstract

Multichannel imaging systems currently feature refocusing capabilities only in bulky and expensive designs. Mechanical movements of the components cannot be integrated in miniaturized designs, preventing classical refocusing mechanisms. To overcome this limitation we developed, as a proof-of-concept (POC) demonstration, a compact low-cost two-channel refocusing imaging system based on a voltage-tunable liquid lens. In addition, the design can be realized with wafer-level manufacturing techniques. One channel of the imaging system enables a wide field of view (FOV) of a scene (2×40°) but with a limited angular resolution (0.078°), while the other channel gives a high angular resolution (0.0098°) image of a small region of interest but with a much narrower FOV (2×7.57°). It is this high-resolution channel that contains the tunable lens and therefore the refocusing capability. A POC demonstration of the proposed two-channel system was built and its performances were measured. Both imaging channels show good overall diffraction-limited image quality.

© 2014 Optical Society of America

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  1. L. Marcenaro, L. Marchesotti, and C. S. Regazzoni, “A multiresolution outdoor dual camera system for robust video-event meta data extraction,” in Proceedings of International Society of Information Fusion (ISIF, 2002), pp. 1184–1189.
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    [Crossref]
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    [Crossref]
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    [Crossref]
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    [Crossref]
  11. M. Tan, “Varioptic unveils Arctic 320 camera phone liquid lens,” Mobile Magazine, 2006, http://www.mobilemag.com/2006/01/24/varioptic-unveils-arctic-320-camera-phone-liquid-lens/ .
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  13. S. Sinzinger and J. Jahns, “Maréchal criterion,” in Microoptics (Wiley-VCH, 2003).
  14. Varioptic, “Technical datasheet Arctic 320” (personal communication, 2010).
  15. P. D. Burns, “Slanted-edge MTF for digital camera and scanner analysis,” in Proceedings of IS &T 2000 PICS Conference, (Society for Imaging Science, 2000), pp. 135–138.
  16. C. Mitjà, J. Escofet, A. Tacho, and R. Revuelta, “Slanted edge MTF,” http://rsb.info.nih.gov/ij/plugins/se-mtf/index.html .

2013 (1)

2012 (1)

2007 (1)

R. Shamai, D. Andelman, B. Berge, and R. Hayes, “Water, electricity, and between… on electrowetting and its applications,” Soft Matter 4, 38–45 (2007).
[Crossref]

2006 (1)

J. Duparré and F. Wippermann, “Micro-optical artificial compound eyes,” Bioinspir. Biomim. 1, R1–R16 (2006).
[Crossref]

2000 (1)

B. Berge and J. Peseux, “Variable focal lens controlled by an external voltage: an application of electrowetting,” Eur. Phys. J. E 3, 159–163 (2000).
[Crossref]

Andelman, D.

R. Shamai, D. Andelman, B. Berge, and R. Hayes, “Water, electricity, and between… on electrowetting and its applications,” Soft Matter 4, 38–45 (2007).
[Crossref]

Belay, G. Y.

Berge, B.

R. Shamai, D. Andelman, B. Berge, and R. Hayes, “Water, electricity, and between… on electrowetting and its applications,” Soft Matter 4, 38–45 (2007).
[Crossref]

B. Berge and J. Peseux, “Variable focal lens controlled by an external voltage: an application of electrowetting,” Eur. Phys. J. E 3, 159–163 (2000).
[Crossref]

Burns, P. D.

P. D. Burns, “Slanted-edge MTF for digital camera and scanner analysis,” in Proceedings of IS &T 2000 PICS Conference, (Society for Imaging Science, 2000), pp. 135–138.

Christensen, M. P.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Coyle, K.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Douglas, S.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Duparré, J.

J. Duparré and F. Wippermann, “Micro-optical artificial compound eyes,” Bioinspir. Biomim. 1, R1–R16 (2006).
[Crossref]

Frattin, D.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Gill, J.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Haack, K.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Hayes, R.

R. Shamai, D. Andelman, B. Berge, and R. Hayes, “Water, electricity, and between… on electrowetting and its applications,” Soft Matter 4, 38–45 (2007).
[Crossref]

Jahns, J.

S. Sinzinger and J. Jahns, “Maréchal criterion,” in Microoptics (Wiley-VCH, 2003).

Krapels, K.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Marcenaro, L.

L. Marcenaro, L. Marchesotti, and C. S. Regazzoni, “A multiresolution outdoor dual camera system for robust video-event meta data extraction,” in Proceedings of International Society of Information Fusion (ISIF, 2002), pp. 1184–1189.

Marchesotti, L.

L. Marcenaro, L. Marchesotti, and C. S. Regazzoni, “A multiresolution outdoor dual camera system for robust video-event meta data extraction,” in Proceedings of International Society of Information Fusion (ISIF, 2002), pp. 1184–1189.

Meuret, Y.

Milojkovic, P.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Myhr, S.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Ottevaere, H.

Papamichalis, P.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Peseux, J.

B. Berge and J. Peseux, “Variable focal lens controlled by an external voltage: an application of electrowetting,” Eur. Phys. J. E 3, 159–163 (2000).
[Crossref]

Rajan, D.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Regazzoni, C. S.

L. Marcenaro, L. Marchesotti, and C. S. Regazzoni, “A multiresolution outdoor dual camera system for robust video-event meta data extraction,” in Proceedings of International Society of Information Fusion (ISIF, 2002), pp. 1184–1189.

Shamai, R.

R. Shamai, D. Andelman, B. Berge, and R. Hayes, “Water, electricity, and between… on electrowetting and its applications,” Soft Matter 4, 38–45 (2007).
[Crossref]

Sinzinger, S.

S. Sinzinger and J. Jahns, “Maréchal criterion,” in Microoptics (Wiley-VCH, 2003).

Somayaji, M.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Thienpont, H.

Van Erps, J.

Veelaert, P.

Vervaeke, M.

Wippermann, F.

J. Duparré and F. Wippermann, “Micro-optical artificial compound eyes,” Bioinspir. Biomim. 1, R1–R16 (2006).
[Crossref]

Appl. Opt. (2)

Bioinspir. Biomim. (1)

J. Duparré and F. Wippermann, “Micro-optical artificial compound eyes,” Bioinspir. Biomim. 1, R1–R16 (2006).
[Crossref]

Eur. Phys. J. E (1)

B. Berge and J. Peseux, “Variable focal lens controlled by an external voltage: an application of electrowetting,” Eur. Phys. J. E 3, 159–163 (2000).
[Crossref]

Soft Matter (1)

R. Shamai, D. Andelman, B. Berge, and R. Hayes, “Water, electricity, and between… on electrowetting and its applications,” Soft Matter 4, 38–45 (2007).
[Crossref]

Other (11)

Vision Systems Design, “Tunable optics,” http://www.vision-systems.com/articles/print/volume-15/issue-7/Features/Tunable_Optics.html .

Varioptic, “Technology: electrowetting,” http://www.varioptic.com/technology/electrowetting/ .

M. Tan, “Varioptic unveils Arctic 320 camera phone liquid lens,” Mobile Magazine, 2006, http://www.mobilemag.com/2006/01/24/varioptic-unveils-arctic-320-camera-phone-liquid-lens/ .

M. Wilson, “Varioptic liquid lenses debut in webcams,” Gizmodo, 2008, http://gizmodo.com/5019642/varioptic-liquid-lenses-debut-in-webcams .

S. Sinzinger and J. Jahns, “Maréchal criterion,” in Microoptics (Wiley-VCH, 2003).

Varioptic, “Technical datasheet Arctic 320” (personal communication, 2010).

P. D. Burns, “Slanted-edge MTF for digital camera and scanner analysis,” in Proceedings of IS &T 2000 PICS Conference, (Society for Imaging Science, 2000), pp. 135–138.

C. Mitjà, J. Escofet, A. Tacho, and R. Revuelta, “Slanted edge MTF,” http://rsb.info.nih.gov/ij/plugins/se-mtf/index.html .

L. Marcenaro, L. Marchesotti, and C. S. Regazzoni, “A multiresolution outdoor dual camera system for robust video-event meta data extraction,” in Proceedings of International Society of Information Fusion (ISIF, 2002), pp. 1184–1189.

P. Milojkovic, J. Gill, D. Frattin, K. Coyle, K. Haack, S. Myhr, D. Rajan, S. Douglas, P. Papamichalis, M. Somayaji, M. P. Christensen, and K. Krapels, “Multichannel, agile, computationally enhanced camera based on PANOPTES architecture,” in Computational Optical Sensing and Imaging, OSA Technical Digest (CD) (Optical Society of America, 2009), paper CTuB4.

Imec 3SIS SBO, “3SIS project summary,” https://projects.imec.be/3sis/ .

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Figures (13)

Fig. 1.
Fig. 1.

Wafer-level stacked image sensor which is comprised of the optical, processing, and sensing layers [3].

Fig. 2.
Fig. 2.

Evolution from the static three-channel imaging system to the two-channel refocusing imaging system. (a) The static three-channel imaging system. (b) The two-channel refocusing imaging system.

Fig. 3.
Fig. 3.

(a) The design of the wide FOV channel (80°) with surfaces 1 to 4 specified in Table 1 [4]. (b) Schematic of the design of the high-resolution channel.

Fig. 4.
Fig. 4.

(a) Tunable lens cavity. The application of a voltage results in a changing lens curvature, through the changing surface tension between the oil and water. (b) Exponential relationship between the focal length and the applied voltage. In the voltage span, between 50.4 and 60.1 Vrms, the lens characteristics are free from hysteresis and the relation between the focal length and the applied voltage is linear. This linear performance of the tunable lens is preserved for reverse illumination, indicated by the crosses. (c) Diffraction-limited performance of the tunable lens, until tilt angles of 16°. Starting at tilt angles of 10°, the wavefront aberrations increase linearly with increasing angles of tilt. For larger applied voltages, the linear curve shows a larger slope.

Fig. 5.
Fig. 5.

(a) The tunable lens model in Code V optical simulation software. (b) Comparison between the diffraction-limited MTF and the measured and simulated horizontal (H) and vertical (V) MTF of the tunable lens cavity.

Fig. 6.
Fig. 6.

MTF for different field heights: on-axis, in the center, and the top of the image sensor. (a) MTF for an applied voltage of 55 Vrms. (b) MTF for an applied voltage of 59 Vrms.

Fig. 7.
Fig. 7.

High-resolution refocusing imaging channel (angular resolution of 0.0098° and FOV of 15.14°).

Fig. 8.
Fig. 8.

Diffraction-limited MTF of the refocusing channel obtained through modeling in CODE V.

Fig. 9.
Fig. 9.

POC setup. (a) Mounted tunable lens. (b) Mounted passive lens. (c) Side view of the POC setup.

Fig. 10.
Fig. 10.

Comparison between the simulated and measured optimal object distance. The corresponding DOF is indicated in the form of “error bars.”

Fig. 11.
Fig. 11.

Comparison between the simulated and measured MTF at 55 and 59 Vrms.

Fig. 12.
Fig. 12.

(a) The refocusing two-channel system. (b) Image quality of an object at the image sensor: (b1) object, (b2) image of the wide FOV channel, and (b3) image of the high-resolution channel.

Fig. 13.
Fig. 13.

Comparison of the image quality of both the high-resolution static (left) and refocusing (right) imaging channel.

Tables (2)

Tables Icon

Table 1. Parameters and Dimensions of the Wide FOV Channel [4]

Tables Icon

Table 2. Parameters of the Passive Lens Surfaces of the High-Resolution Optical Channel

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