Abstract

A focal stack camera, based on an electrically tunable-focusing liquid crystal (LC) lens doped with multi-walled carbon nanotubes, is proposed to generate a single all-in-focus image of a 3D scene without depth map in a relatively short time. Focal sweep strategy of the camera is devised. Both its depth of field (DOF) and focal sweep speed are analyzed and deduced. Nano doping method is adopted to improve electro-optical features of the LC lens. To efficiently produce all-in-focus image, a weighted average algorithm for all images in the focal stack is utilized. The experiments show that the result is a high contrast at sensor resolution. It is greatly potential in optical compact 3D imaging system.

© 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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References

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2017 (3)

2016 (3)

2015 (6)

2014 (3)

2013 (4)

2012 (3)

2011 (3)

S. W. Hasinoff and K. N. Kutulakos, “Light-efficient photography,” IEEE Trans. Pattern Anal. Mach. Intell. 33(11), 2203–2214 (2011).
[Crossref] [PubMed]

H. C. Lin, M. S. Chen, and Y. H. Lin, “A review of electrically tunable focusing liquid crystal lenses,” Trans. Electr. Electron. Mater. 12(6), 234–240 (2011).
[Crossref]

Y. H. Lin, M. S. Chen, and H. C. Lin, “An electrically tunable optical zoom system using two composite liquid crystal lenses with a large zoom ratio,” Opt. Express 19(5), 4714–4721 (2011).
[Crossref] [PubMed]

2009 (1)

2008 (4)

2006 (1)

2004 (2)

2001 (1)

Ahnelt, P. K.

Anderson, P. A.

Bimber, O.

Birklbauer, C.

Butt, H.

Castro, A.

Chen, C. L.

Chen, H. S.

Chen, J.

Chen, L.

Chen, M.

M. S. Chen, P. J. Chen, M. Chen, and Y. H. Lin, “An electrically tunable imaging system with separable focus and zoom functions using composite liquid crystal lenses,” Opt. Express 22(10), 11427–11435 (2014).
[Crossref] [PubMed]

Y. Lin and M. Chen, “A pico projection system with electrically tunable optical zoom ratio adopting two liquid crystal lenses,” J. Disp. Technol. 8(7), 401–404 (2012).
[Crossref]

Chen, M. S.

Chen, P. J.

Chien, L. C.

Chiu, C. S.

Collings, N.

Dai, M.

Drexler, W.

Fan, P.

Feng, S.

C. Huang, Q. Zhang, H. Wang, and S. Feng, “A low power and low complexity automatic white balance algorithm for AMOLED driving using histogram matching,” J. Disp. Technol. 11(1), 53–59 (2015).
[Crossref]

Fernández, E. J.

Fox, D.

Geng, J.

J. Geng, “Three-dimensional display technologies,” Adv. Opt. Photonics 5(4), 456–535 (2013).
[Crossref] [PubMed]

Guo, L.

Hamarová, I.

Hasinoff, S. W.

S. W. Hasinoff and K. N. Kutulakos, “Light-efficient photography,” IEEE Trans. Pattern Anal. Mach. Intell. 33(11), 2203–2214 (2011).
[Crossref] [PubMed]

Hermann, B.

Hofer, B.

Hong, S. H.

Hu, J.

Huang, C.

C. Huang, Q. Zhang, H. Wang, and S. Feng, “A low power and low complexity automatic white balance algorithm for AMOLED driving using histogram matching,” J. Disp. Technol. 11(1), 53–59 (2015).
[Crossref]

Hui, L.

Izadi, S.

Jang, J. S.

Javidi, B.

Jeong, Y.

Jiang, M.

Kim, J.

Koppelhuber, A.

Kutulakos, K. N.

S. W. Hasinoff and K. N. Kutulakos, “Light-efficient photography,” IEEE Trans. Pattern Anal. Mach. Intell. 33(11), 2203–2214 (2011).
[Crossref] [PubMed]

Lam, E. Y.

Lee, B.

Lee, C. K.

Lee, W.

Li, H.

Li, J.

Li, M.

Li, W.

Li, Y.

S. Xu, Y. Li, Y. Liu, J. Sun, H. Ren, and S. T. Wu, “Fast-response liquid crystal microlens,” Micromachines (Basel) 5(2), 300–324 (2014).
[Crossref]

Liao, Q.

Lin, H. C.

Lin, Y.

Y. Lin and M. Chen, “A pico projection system with electrically tunable optical zoom ratio adopting two liquid crystal lenses,” J. Disp. Technol. 8(7), 401–404 (2012).
[Crossref]

H. Ren, S. Xu, Y. Lin, and S. Wu, “Adaptive-focus lenses,” Opt. Photonics News 19(10), 42–47 (2008).
[Crossref]

Lin, Y. H.

Liu, C.

Liu, Y.

S. Xu, Y. Li, Y. Liu, J. Sun, H. Ren, and S. T. Wu, “Fast-response liquid crystal microlens,” Micromachines (Basel) 5(2), 300–324 (2014).
[Crossref]

Lu, S. Y.

Magdaleno, E.

F. Perez, A. Perez, M. Rodriguez, and E. Magdaleno, “A fast and memory-efficient discrete focal stack transform for plenoptic sensors,” Digit. Signal Process. 38, 95–105 (2015).
[Crossref]

Martinez-Corral, M.

Ojeda-Castañeda, J.

Pan, F.

Pavlicek, P.

Peng, R.

Perez, A.

F. Perez, A. Perez, M. Rodriguez, and E. Magdaleno, “A fast and memory-efficient discrete focal stack transform for plenoptic sensors,” Digit. Signal Process. 38, 95–105 (2015).
[Crossref]

Perez, F.

F. Perez, A. Perez, M. Rodriguez, and E. Magdaleno, “A fast and memory-efficient discrete focal stack transform for plenoptic sensors,” Digit. Signal Process. 38, 95–105 (2015).
[Crossref]

Považay, B.

Qin, H.

Qiu, J.

Rajasekharan-Unnithan, R.

Ren, H.

S. Xu, Y. Li, Y. Liu, J. Sun, H. Ren, and S. T. Wu, “Fast-response liquid crystal microlens,” Micromachines (Basel) 5(2), 300–324 (2014).
[Crossref]

H. Ren, S. Xu, Y. Lin, and S. Wu, “Adaptive-focus lenses,” Opt. Photonics News 19(10), 42–47 (2008).
[Crossref]

H. Ren, D. Fox, P. A. Anderson, B. Wu, and S. T. Wu, “Tunable-focus liquid lens controlled using a servo motor,” Opt. Express 14(18), 8031–8036 (2006).
[Crossref] [PubMed]

Rodriguez, M.

F. Perez, A. Perez, M. Rodriguez, and E. Magdaleno, “A fast and memory-efficient discrete focal stack transform for plenoptic sensors,” Digit. Signal Process. 38, 95–105 (2015).
[Crossref]

Sattmann, H.

Shen, X.

Shentu, L.

Stern, A.

Sun, J.

S. Xu, Y. Li, Y. Liu, J. Sun, H. Ren, and S. T. Wu, “Fast-response liquid crystal microlens,” Micromachines (Basel) 5(2), 300–324 (2014).
[Crossref]

Unterhuber, A.

Wang, G.

Wang, H.

C. Huang, Q. Zhang, H. Wang, and S. Feng, “A low power and low complexity automatic white balance algorithm for AMOLED driving using histogram matching,” J. Disp. Technol. 11(1), 53–59 (2015).
[Crossref]

Wang, Y. J.

Wilkinson, T. D.

Wu, B.

Wu, S.

H. Ren, S. Xu, Y. Lin, and S. Wu, “Adaptive-focus lenses,” Opt. Photonics News 19(10), 42–47 (2008).
[Crossref]

Wu, S. T.

S. Xu, Y. Li, Y. Liu, J. Sun, H. Ren, and S. T. Wu, “Fast-response liquid crystal microlens,” Micromachines (Basel) 5(2), 300–324 (2014).
[Crossref]

H. Ren, D. Fox, P. A. Anderson, B. Wu, and S. T. Wu, “Tunable-focus liquid lens controlled using a servo motor,” Opt. Express 14(18), 8031–8036 (2006).
[Crossref] [PubMed]

Wu, Y.

Xi, J.

Xiao, X.

Xiaolin, X.

Xie, X.

Xu, S.

S. Xu, Y. Li, Y. Liu, J. Sun, H. Ren, and S. T. Wu, “Fast-response liquid crystal microlens,” Micromachines (Basel) 5(2), 300–324 (2014).
[Crossref]

H. Ren, S. Xu, Y. Lin, and S. Wu, “Adaptive-focus lenses,” Opt. Photonics News 19(10), 42–47 (2008).
[Crossref]

Yan, X.

Yanduo, Z.

Yang, T.

Yeom, J.

Yin, X.

Yuntao, W.

Zhang, Q.

C. Huang, Q. Zhang, H. Wang, and S. Feng, “A low power and low complexity automatic white balance algorithm for AMOLED driving using histogram matching,” J. Disp. Technol. 11(1), 53–59 (2015).
[Crossref]

Zhang, Y.

Zhou, H.

Zhu, M.

Zhuang, S.

Adv. Opt. Photonics (1)

J. Geng, “Three-dimensional display technologies,” Adv. Opt. Photonics 5(4), 456–535 (2013).
[Crossref] [PubMed]

Appl. Opt. (9)

J. Xi, L. Shentu, J. Hu, and M. Li, “Automated surface inspection for steel products using computer vision approach,” Appl. Opt. 56(2), 184–192 (2017).
[Crossref] [PubMed]

A. Castro and J. Ojeda-Castañeda, “Asymmetric phase masks for extended depth of field,” Appl. Opt. 43(17), 3474–3479 (2004).
[Crossref] [PubMed]

X. Yin, G. Wang, W. Li, and Q. Liao, “Iteratively reconstructing 4D light fields from focal stacks,” Appl. Opt. 55(30), 8457–8463 (2016).
[Crossref] [PubMed]

X. Yan, H. Qin, J. Li, H. Zhou, and T. Yang, “Multi-focus image fusion using a guided-filter-based difference image,” Appl. Opt. 55(9), 2230–2239 (2016).
[Crossref] [PubMed]

Y. Jeong, J. Kim, J. Yeom, C. K. Lee, and B. Lee, “Real-time depth controllable integral imaging pickup and reconstruction method with a light field camera,” Appl. Opt. 54(35), 10333–10341 (2015).
[Crossref] [PubMed]

H. Li, F. Pan, Y. Wu, Y. Zhang, and X. Xie, “Improvement in imaging contrast feature of liquid crystal lens with the dopant of multi-walled carbon nanotubes,” Appl. Opt. 56(23), 6655–6662 (2017).
[Crossref] [PubMed]

L. Hui, P. Fan, W. Yuntao, Z. Yanduo, and X. Xiaolin, “Depth map sensor based on optical doped lens with multi-walled carbon nanotubes of liquid crystal,” Appl. Opt. 55(1), 140–147 (2016).
[Crossref] [PubMed]

P. Pavliček and I. Hamarová, “Shape from focus for large image fields,” Appl. Opt. 54(33), 9747–9751 (2015).
[Crossref] [PubMed]

X. Xiao, B. Javidi, M. Martinez-Corral, and A. Stern, “Advances in three-dimensional integral imaging: sensing, display, and applications [Invited],” Appl. Opt. 52(4), 546–560 (2013).
[Crossref] [PubMed]

Digit. Signal Process. (1)

F. Perez, A. Perez, M. Rodriguez, and E. Magdaleno, “A fast and memory-efficient discrete focal stack transform for plenoptic sensors,” Digit. Signal Process. 38, 95–105 (2015).
[Crossref]

IEEE Trans. Pattern Anal. Mach. Intell. (1)

S. W. Hasinoff and K. N. Kutulakos, “Light-efficient photography,” IEEE Trans. Pattern Anal. Mach. Intell. 33(11), 2203–2214 (2011).
[Crossref] [PubMed]

J. Disp. Technol. (2)

C. Huang, Q. Zhang, H. Wang, and S. Feng, “A low power and low complexity automatic white balance algorithm for AMOLED driving using histogram matching,” J. Disp. Technol. 11(1), 53–59 (2015).
[Crossref]

Y. Lin and M. Chen, “A pico projection system with electrically tunable optical zoom ratio adopting two liquid crystal lenses,” J. Disp. Technol. 8(7), 401–404 (2012).
[Crossref]

J. Opt. Soc. Am. A (2)

Micromachines (Basel) (1)

S. Xu, Y. Li, Y. Liu, J. Sun, H. Ren, and S. T. Wu, “Fast-response liquid crystal microlens,” Micromachines (Basel) 5(2), 300–324 (2014).
[Crossref]

Opt. Express (12)

H. Ren, D. Fox, P. A. Anderson, B. Wu, and S. T. Wu, “Tunable-focus liquid lens controlled using a servo motor,” Opt. Express 14(18), 8031–8036 (2006).
[Crossref] [PubMed]

L. Chen, J. Li, and C. L. Chen, “Regional multifocus image fusion using sparse representation,” Opt. Express 21(4), 5182–5197 (2013).
[Crossref] [PubMed]

L. Guo, M. Dai, and M. Zhu, “Multifocus color image fusion based on quaternion curvelet transform,” Opt. Express 20(17), 18846–18860 (2012).
[Crossref] [PubMed]

A. Koppelhuber, C. Birklbauer, S. Izadi, and O. Bimber, “A transparent thin-film sensor for multi-focal image reconstruction and depth estimation,” Opt. Express 22(8), 8928–8942 (2014).
[Crossref] [PubMed]

C. Liu, J. Qiu, and M. Jiang, “Light field reconstruction from projection modeling of focal stack,” Opt. Express 25(10), 11377–11388 (2017).
[Crossref] [PubMed]

E. J. Fernández, B. Hermann, B. Považay, A. Unterhuber, H. Sattmann, B. Hofer, P. K. Ahnelt, and W. Drexler, “Ultrahigh resolution optical coherence tomography and pancorrection for cellular imaging of the living human retina,” Opt. Express 16(15), 11083–11094 (2008).
[Crossref] [PubMed]

S. H. Hong, J. S. Jang, and B. Javidi, “Three-dimensional volumetric object reconstruction using computational integral imaging,” Opt. Express 12(3), 483–491 (2004).
[Crossref] [PubMed]

H. C. Lin, N. Collings, M. S. Chen, and Y. H. Lin, “A holographic projection system with an electrically tuning and continuously adjustable optical zoom,” Opt. Express 20(25), 27222–27229 (2012).
[Crossref] [PubMed]

H. S. Chen and Y. H. Lin, “An endoscopic system adopting a liquid crystal lens with an electrically tunable depth-of-field,” Opt. Express 21(15), 18079–18088 (2013).
[Crossref] [PubMed]

Y. H. Lin, M. S. Chen, and H. C. Lin, “An electrically tunable optical zoom system using two composite liquid crystal lenses with a large zoom ratio,” Opt. Express 19(5), 4714–4721 (2011).
[Crossref] [PubMed]

M. S. Chen, P. J. Chen, M. Chen, and Y. H. Lin, “An electrically tunable imaging system with separable focus and zoom functions using composite liquid crystal lenses,” Opt. Express 22(10), 11427–11435 (2014).
[Crossref] [PubMed]

S. Y. Lu and L. C. Chien, “Carbon nanotube doped liquid crystal OCB cells: physical and electro-optical properties,” Opt. Express 16(17), 12777–12785 (2008).
[Crossref] [PubMed]

Opt. Lett. (3)

Opt. Photonics News (1)

H. Ren, S. Xu, Y. Lin, and S. Wu, “Adaptive-focus lenses,” Opt. Photonics News 19(10), 42–47 (2008).
[Crossref]

Trans. Electr. Electron. Mater. (1)

H. C. Lin, M. S. Chen, and Y. H. Lin, “A review of electrically tunable focusing liquid crystal lenses,” Trans. Electr. Electron. Mater. 12(6), 234–240 (2011).
[Crossref]

Other (6)

K. Kutulakos and S. Hasinoff, “ Focal stack photography: High-performance photography with a conventional camera, ” in Proc. 11th IAPR Conference on Mach. Vision Appl. 332–337 (2009).

F. Jenkins and H. White, Fundamentals of Optics (McGraw-Hill Education, 2001).

H. Ren and S. T. Wu, Introduction to Adaptive Lenses (John Wiley, 2012).

R. C. Gonzalez and R. E. Woods, Digital Image Processing (Pearson, 3 edition, 2007).

C. Zhou, D. Miau, and S. K. Nayar, “Focal sweep camera for space-time refocusing, ” http://www1.cs.columbia.edu/CAVE/projects/focal_sweep_camera/ .

D. E. Jacobs, J. Baek, and M. Levoy, “Focal stack compositing for depth of field control,” https://graphics.stanford.edu/papers/focalstack/ .

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Figures (10)

Fig. 1
Fig. 1 Efficient and complete focal sweep strategy.
Fig. 2
Fig. 2 DOF of the proposed focal stack camera.
Fig. 3
Fig. 3 The pipeline of the image fusion algorithm for producing all-in-focus image.
Fig. 4
Fig. 4 The structure of the proposed LC lens.
Fig. 5
Fig. 5 Classic optoelectronic properties of the LC lens. (a) is the phase profile of the LC lens at 1.5Vrms; (b) is the phase profile of the LC lens at 2.5Vrms; (c) The lens power of the LC lens as the function of the applied voltage, those red circular dots mean the LC lens doped with MWCNTs, and those blue square dots mean the conventional LC lens without any dopant.
Fig. 6
Fig. 6 Three focused states in the focal stack based on the LC lens. (c) is at 1.0Vrms; (b) is at 2.5Vrms; (a) is at 4.0Vrms.
Fig. 7
Fig. 7 The focus measure function of 2D images in the focal stack at different applied voltages. (a) is at 0.5Vrms; (b) is at 1.0Vrms; (c) is at 1.5Vrms; (d) is at 2.0Vrms; (e) is at 2.5Vrms; (f) is at 3.0Vrms; (g) is at 3.5Vrms; (h) is at 4.0Vrms; (i) is at 4.5Vrms; (j) is at 5.0Vrms.
Fig. 8
Fig. 8 The weight value as a function of applied voltage, which is calculated for every 2D image in the focal stack.
Fig. 9
Fig. 9 PSNR and RMSE for 2D images in the focal stack at different applied voltages.
Fig. 10
Fig. 10 All-in-focus image computed using different approaches and their close-ups. (a) The DCT method to fuse all 2D images in the focal stack; (b) The average method to fuse all 2D images in the focal stack; (c) The weighted average method to fuse all 2D images in the focal stack; (d) The best focused patches in the captured focal stack.

Tables (2)

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Table 1 Comparison results about switching time between the LC lens doped with MWCNTs and the conventional LC lensa

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Table 2 The specification of the focal stack camera based on the proposed LC lens a

Equations (14)

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DOF=| m 1 m 3 |=2| p 3 p 1 | c LC r LC .
f ^ L = n ^ 1 + q ^ 1 ,
f ^ L = n ^ 2 + q ^ 2 ,
f ^ L = n ^ 3 + q ^ 3 .
| q ^ 3 q ^ 1 |=| n ^ 3 n ^ 1 |.
| q 3 q 1 |= q 3 q 1 | n ^ 3 n ^ 1 |.
| p 3 p 1 |= q 3 q 1 | n ^ 3 n ^ 1 |.
1 f LC ( V 1 ) = 1 m + 1 p ,
1 f LC ( V 2 ) = 1 m' + 1 p' .
| f ^ LC ( V 2 ) f ^ LC ( V 1 ) |=| m ^ ' m ^ + p ^ ' p ^ |.
Δf= f LC ( V 1 ) f LC ( V 2 )| Δm m'm + Δp p'p |.
Δf f LCmin f LCmax | f LCmin f LCmax |.
a k (i,j)= | G k (i,j) | | L k (i,j) |+ε ,k=1,,M.
I(x,y)= i a k (x,y) I k (x,y) i a k (x,y)+ε .

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