Abstract

Conventional endoscopic systems consisting of several solid lenses suffer from a fixed and limited depth-of-field (DOF). For practical applications, conventional endoscopes mechanically change the distance between the solid lenses of a lens module in order to change the focusing plane and DOF to see clearly in a scene. In this paper, we demonstrate an electrically tunable endoscopic system adopting a liquid crystal lens. By means of tunable focusing properties of the LC lens as a positive lens and a negative lens, the object at different objective distances can be imaged to the image sensor clearly and the corresponding depth-of-field can also help to enlarge the total spatial depth perception in a scene. The optical mechanism is discussed. In the experiments, under adjustment of three discrete lens powers of the LC lens, the viewing range or total spatial depth perception of the endoscopic system is from 76.4 mm to 12.4 mm which is 2x improved compared to the conventional one without LC lens. We believe this study can be extended to the applications of industrial and medical endoscopes.

© 2013 OSA

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2013 (2)

2012 (4)

H. C. Lin and Y. H. Lin, “An electrically tunable-focusing liquid crystal lens with a low voltage and simple electrodes,” Opt. Express20(3), 2045–2052 (2012).
[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. Express20(25), 27222–27229 (2012).
[CrossRef] [PubMed]

Y. H. Lin, M. S. Chen, W. C. Lin, and Y. S. Tsou, “A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degree twisted cell,” J. Appl. Phys.112(2), 024505 (2012).
[CrossRef]

Y. S. Tsou, Y. H. Lin, and A. C. Wei, “Concentrating Photovoltaic System Using a Liquid Crystal Lens,” IEEE Photon. Technol. Lett.24(24), 2239–2242 (2012).
[CrossRef]

2011 (6)

Y. H. Lin and Y. S. Tsou, “A polarization independent liquid crystal phase modulation adopting surface pinning effect of polymer dispersed liquid crystals,” J. Appl. Phys.110(11), 114516 (2011).
[CrossRef]

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]

H. C. Lin and Y. H. Lin, “An electrically tunable focusing liquid crystal lens with built-in planar polymeric lens,” Appl. Phys. Lett.98(8), 083503 (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. Express19(5), 4714–4721 (2011).
[CrossRef] [PubMed]

S. Kuiper, “Electrowetting-based liquid lenses for endoscopy,” Proc. SPIE7930, 793008, 793008-8 (2011).
[CrossRef]

X. Zeng, C. T. Smith, J. C. Gould, C. P. Heise, and H. Jiang, “Fiber endoscopes utilizing liquid tunable-focus microlenses actuated through infrared light,” J. of Microelectromechannical Systems20(3), 583–593 (2011).
[CrossRef]

2010 (6)

S. W. Seo, S. Han, J. H. Seo, W. B. Choi, and M. Y. Sung, “Liquid lens module with wide field-of view and variable focal length,” Electronic Mater. Lett.6(4), 141–144 (2010).
[CrossRef]

H. C. Lin and Y. H. Lin, “A fast response and large electrically tunable-focusing imaging system based on switching of two modes of a liquid crystal lens,” Appl. Phys. Lett.97(6), 063505 (2010).
[CrossRef]

H. C. Lin and Y. H. Lin, “An electrically tunable focusing pico-projector adopting a liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 102502 (2010).
[CrossRef]

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

Y. H. Lin, H. S. Chen, H. C. Lin, Y. S. Tsou, H. K. Hsu, and W. Y. Li, “Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals,” Appl. Phys. Lett.96(11), 113505 (2010).
[CrossRef]

P. Valley, D. L. Mathine, M. R. Dodge, J. Schwiegerling, G. Peyman, and N. Peyghambarian, “Tunable-focus flat liquid-crystal diffractive lens,” Opt. Lett.35(3), 336–338 (2010).
[CrossRef] [PubMed]

2009 (2)

R. El-Maksoud, L. Wang, J. M. Sasian, and V. S. Valencia, “Depth of field estimation: theory, experiment, and application,” Proc. SPIE7429, 74290W, 74290W-12 (2009).
[CrossRef]

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

2008 (2)

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (2008).
[CrossRef]

Y. H. Lin, H. Ren, and S. T. Wu, “Polarisation-independent liquid crystal devices,” Liquid Crystals Today17(1-2), 2–8 (2008).
[CrossRef]

2006 (3)

Y. Huang, C. H. Wen, and S. T. Wu, “Polarization-independent and submillisecond response phase modulators using a 90° twisted dual-frequency liquid crystal,” Appl. Phys. Lett.89(2), 021103 (2006).
[CrossRef]

H. Ren, Y. H. Lin, and S. T. Wu, “Polarization-independent and fast-response phase modulators using double-layered liquid crystal gels,” Appl. Phys. Lett.88(6), 061123 (2006).
[CrossRef]

B. Wang, M. Ye, and S. Sato, “Liquid crystal lens with focal length variable from negative to positive values,” IEEE Photon. Technol. Lett.18(1), 79–81 (2006).
[CrossRef]

2005 (4)

Y. H. Lin, H. Ren, Y. H. Wu, Y. Zhao, J. Y. Fang, Z. Ge, and S. T. Wu, “Polarization-independent liquid crystal phase modulator using a thin polymer-separated double-layered structure,” Opt. Express13(22), 8746–8752 (2005).
[CrossRef] [PubMed]

H. Ren, Y. H. Lin, Y. H. Fan, and S. T. Wu, “Polarization-independent phase modulation using a polymer-dispersed liquid crystal,” Appl. Phys. Lett.86(14), 141110 (2005).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Fan, Y. H. Wu, and S. T. Wu, “Polarization-independent and fast-response phase modulation using a normal-mode polymer-stabilized cholesteric texture,” J. Appl. Phys.98(4), 043112 (2005).
[CrossRef]

H. Ren, Y. H. Lin, C. H. Wen, and S. T. Wu, “Polarization-independent phase modulation of a homeotropic liquid crystal gel,” Appl. Phys. Lett.87(19), 191106 (2005).
[CrossRef]

2002 (2)

H. Ren and S. T. Wu, “Inhomogeneous nanoscale polymer-dispersed liquid crystals with gradient refractive index,” Appl. Phys. Lett.81(19), 3537–3539 (2002).
[CrossRef]

D. E. Lucchetta, R. Karapinar, A. Manni, and F. Simoni, “Phase-only modulation by nanosized polymer-dispersed liquid crystals,” J. Appl. Phys.91(9), 6060–6065 (2002).
[CrossRef]

1995 (1)

P. Rol, R. Jenny, D. Beck, F. Frankhauser, and P. F. Niederer, “Optical properties of miniatured endoscopes for ophthalmic use,” Opt. Eng.34(7), 2070–2077 (1995).
[CrossRef]

Beck, D.

P. Rol, R. Jenny, D. Beck, F. Frankhauser, and P. F. Niederer, “Optical properties of miniatured endoscopes for ophthalmic use,” Opt. Eng.34(7), 2070–2077 (1995).
[CrossRef]

Chen, H. S.

Y. H. Lin and H. S. Chen, “Electrically tunable-focusing and polarizer-free liquid crystal lenses for ophthalmic applications,” Opt. Express21(8), 9428–9436 (2013).
[CrossRef] [PubMed]

Y. H. Lin, H. S. Chen, H. C. Lin, Y. S. Tsou, H. K. Hsu, and W. Y. Li, “Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals,” Appl. Phys. Lett.96(11), 113505 (2010).
[CrossRef]

H. S. Chen and Y. H. Lin, “An electrically tunable endoscopic system by adding a liquid crystal lens to enlarge and shift depth-of field,” SPIE8828 (2013).

Chen, M. S.

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. Express20(25), 27222–27229 (2012).
[CrossRef] [PubMed]

Y. H. Lin, M. S. Chen, W. C. Lin, and Y. S. Tsou, “A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degree twisted cell,” J. Appl. Phys.112(2), 024505 (2012).
[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. Express19(5), 4714–4721 (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]

Chen, Z. Y.

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (2008).
[CrossRef]

Choi, W. B.

S. W. Seo, S. Han, J. H. Seo, W. B. Choi, and M. Y. Sung, “Liquid lens module with wide field-of view and variable focal length,” Electronic Mater. Lett.6(4), 141–144 (2010).
[CrossRef]

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

Collings, N.

Dodge, M. R.

El-Maksoud, R.

R. El-Maksoud, L. Wang, J. M. Sasian, and V. S. Valencia, “Depth of field estimation: theory, experiment, and application,” Proc. SPIE7429, 74290W, 74290W-12 (2009).
[CrossRef]

Fan, Y. H.

H. Ren, Y. H. Lin, Y. H. Fan, and S. T. Wu, “Polarization-independent phase modulation using a polymer-dispersed liquid crystal,” Appl. Phys. Lett.86(14), 141110 (2005).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Fan, Y. H. Wu, and S. T. Wu, “Polarization-independent and fast-response phase modulation using a normal-mode polymer-stabilized cholesteric texture,” J. Appl. Phys.98(4), 043112 (2005).
[CrossRef]

Fang, J. Y.

Feng, H. M.

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (2008).
[CrossRef]

Frankhauser, F.

P. Rol, R. Jenny, D. Beck, F. Frankhauser, and P. F. Niederer, “Optical properties of miniatured endoscopes for ophthalmic use,” Opt. Eng.34(7), 2070–2077 (1995).
[CrossRef]

Ge, Z.

Gould, J. C.

X. Zeng, C. T. Smith, J. C. Gould, C. P. Heise, and H. Jiang, “Fiber endoscopes utilizing liquid tunable-focus microlenses actuated through infrared light,” J. of Microelectromechannical Systems20(3), 583–593 (2011).
[CrossRef]

Han, S.

S. W. Seo, S. Han, J. H. Seo, W. B. Choi, and M. Y. Sung, “Liquid lens module with wide field-of view and variable focal length,” Electronic Mater. Lett.6(4), 141–144 (2010).
[CrossRef]

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

Heise, C. P.

X. Zeng, C. T. Smith, J. C. Gould, C. P. Heise, and H. Jiang, “Fiber endoscopes utilizing liquid tunable-focus microlenses actuated through infrared light,” J. of Microelectromechannical Systems20(3), 583–593 (2011).
[CrossRef]

Hsu, H. K.

Y. H. Lin, H. S. Chen, H. C. Lin, Y. S. Tsou, H. K. Hsu, and W. Y. Li, “Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals,” Appl. Phys. Lett.96(11), 113505 (2010).
[CrossRef]

Huang, S. W.

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (2008).
[CrossRef]

Huang, Y.

Y. Huang, C. H. Wen, and S. T. Wu, “Polarization-independent and submillisecond response phase modulators using a 90° twisted dual-frequency liquid crystal,” Appl. Phys. Lett.89(2), 021103 (2006).
[CrossRef]

Jenny, R.

P. Rol, R. Jenny, D. Beck, F. Frankhauser, and P. F. Niederer, “Optical properties of miniatured endoscopes for ophthalmic use,” Opt. Eng.34(7), 2070–2077 (1995).
[CrossRef]

Jiang, H.

X. Zeng, C. T. Smith, J. C. Gould, C. P. Heise, and H. Jiang, “Fiber endoscopes utilizing liquid tunable-focus microlenses actuated through infrared light,” J. of Microelectromechannical Systems20(3), 583–593 (2011).
[CrossRef]

Kang, M. S.

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

Karapinar, R.

D. E. Lucchetta, R. Karapinar, A. Manni, and F. Simoni, “Phase-only modulation by nanosized polymer-dispersed liquid crystals,” J. Appl. Phys.91(9), 6060–6065 (2002).
[CrossRef]

Kim, Y. M.

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

Kuiper, S.

S. Kuiper, “Electrowetting-based liquid lenses for endoscopy,” Proc. SPIE7930, 793008, 793008-8 (2011).
[CrossRef]

Kuo, Y. T.

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (2008).
[CrossRef]

Li, W. Y.

Y. H. Lin, H. S. Chen, H. C. Lin, Y. S. Tsou, H. K. Hsu, and W. Y. Li, “Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals,” Appl. Phys. Lett.96(11), 113505 (2010).
[CrossRef]

Lin, H. C.

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. Express20(25), 27222–27229 (2012).
[CrossRef] [PubMed]

H. C. Lin and Y. H. Lin, “An electrically tunable-focusing liquid crystal lens with a low voltage and simple electrodes,” Opt. Express20(3), 2045–2052 (2012).
[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. Express19(5), 4714–4721 (2011).
[CrossRef] [PubMed]

H. C. Lin and Y. H. Lin, “An electrically tunable focusing liquid crystal lens with built-in planar polymeric lens,” Appl. Phys. Lett.98(8), 083503 (2011).
[CrossRef]

H. C. Lin and Y. H. Lin, “An electrically tunable focusing pico-projector adopting a liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 102502 (2010).
[CrossRef]

Y. H. Lin, H. S. Chen, H. C. Lin, Y. S. Tsou, H. K. Hsu, and W. Y. Li, “Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals,” Appl. Phys. Lett.96(11), 113505 (2010).
[CrossRef]

H. C. Lin and Y. H. Lin, “A fast response and large electrically tunable-focusing imaging system based on switching of two modes of a liquid crystal lens,” Appl. Phys. Lett.97(6), 063505 (2010).
[CrossRef]

Lin, W. C.

Y. H. Lin, M. S. Chen, W. C. Lin, and Y. S. Tsou, “A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degree twisted cell,” J. Appl. Phys.112(2), 024505 (2012).
[CrossRef]

Lin, Y. H.

Y. H. Lin and H. S. Chen, “Electrically tunable-focusing and polarizer-free liquid crystal lenses for ophthalmic applications,” Opt. Express21(8), 9428–9436 (2013).
[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. Express20(25), 27222–27229 (2012).
[CrossRef] [PubMed]

Y. H. Lin, M. S. Chen, W. C. Lin, and Y. S. Tsou, “A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degree twisted cell,” J. Appl. Phys.112(2), 024505 (2012).
[CrossRef]

Y. S. Tsou, Y. H. Lin, and A. C. Wei, “Concentrating Photovoltaic System Using a Liquid Crystal Lens,” IEEE Photon. Technol. Lett.24(24), 2239–2242 (2012).
[CrossRef]

H. C. Lin and Y. H. Lin, “An electrically tunable-focusing liquid crystal lens with a low voltage and simple electrodes,” Opt. Express20(3), 2045–2052 (2012).
[CrossRef] [PubMed]

Y. H. Lin and Y. S. Tsou, “A polarization independent liquid crystal phase modulation adopting surface pinning effect of polymer dispersed liquid crystals,” J. Appl. Phys.110(11), 114516 (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. Express19(5), 4714–4721 (2011).
[CrossRef] [PubMed]

H. C. Lin and Y. H. Lin, “An electrically tunable focusing liquid crystal lens with built-in planar polymeric lens,” Appl. Phys. Lett.98(8), 083503 (2011).
[CrossRef]

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]

H. C. Lin and Y. H. Lin, “An electrically tunable focusing pico-projector adopting a liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 102502 (2010).
[CrossRef]

Y. H. Lin, H. S. Chen, H. C. Lin, Y. S. Tsou, H. K. Hsu, and W. Y. Li, “Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals,” Appl. Phys. Lett.96(11), 113505 (2010).
[CrossRef]

H. C. Lin and Y. H. Lin, “A fast response and large electrically tunable-focusing imaging system based on switching of two modes of a liquid crystal lens,” Appl. Phys. Lett.97(6), 063505 (2010).
[CrossRef]

Y. H. Lin, H. Ren, and S. T. Wu, “Polarisation-independent liquid crystal devices,” Liquid Crystals Today17(1-2), 2–8 (2008).
[CrossRef]

H. Ren, Y. H. Lin, and S. T. Wu, “Polarization-independent and fast-response phase modulators using double-layered liquid crystal gels,” Appl. Phys. Lett.88(6), 061123 (2006).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Wu, Y. Zhao, J. Y. Fang, Z. Ge, and S. T. Wu, “Polarization-independent liquid crystal phase modulator using a thin polymer-separated double-layered structure,” Opt. Express13(22), 8746–8752 (2005).
[CrossRef] [PubMed]

H. Ren, Y. H. Lin, Y. H. Fan, and S. T. Wu, “Polarization-independent phase modulation using a polymer-dispersed liquid crystal,” Appl. Phys. Lett.86(14), 141110 (2005).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Fan, Y. H. Wu, and S. T. Wu, “Polarization-independent and fast-response phase modulation using a normal-mode polymer-stabilized cholesteric texture,” J. Appl. Phys.98(4), 043112 (2005).
[CrossRef]

H. Ren, Y. H. Lin, C. H. Wen, and S. T. Wu, “Polarization-independent phase modulation of a homeotropic liquid crystal gel,” Appl. Phys. Lett.87(19), 191106 (2005).
[CrossRef]

H. S. Chen and Y. H. Lin, “An electrically tunable endoscopic system by adding a liquid crystal lens to enlarge and shift depth-of field,” SPIE8828 (2013).

Liu, Y.

Lucchetta, D. E.

D. E. Lucchetta, R. Karapinar, A. Manni, and F. Simoni, “Phase-only modulation by nanosized polymer-dispersed liquid crystals,” J. Appl. Phys.91(9), 6060–6065 (2002).
[CrossRef]

Manni, A.

D. E. Lucchetta, R. Karapinar, A. Manni, and F. Simoni, “Phase-only modulation by nanosized polymer-dispersed liquid crystals,” J. Appl. Phys.91(9), 6060–6065 (2002).
[CrossRef]

Mathine, D. L.

Min, N. K.

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

Niederer, P. F.

P. Rol, R. Jenny, D. Beck, F. Frankhauser, and P. F. Niederer, “Optical properties of miniatured endoscopes for ophthalmic use,” Opt. Eng.34(7), 2070–2077 (1995).
[CrossRef]

Peyghambarian, N.

Peyman, G.

Ren, H.

H. Ren, S. Xu, Y. Liu, and S. T. Wu, “Switchable focus using a polymeric lenticular microlens array and a polarization rotator,” Opt. Express21(7), 7916–7925 (2013).
[CrossRef] [PubMed]

Y. H. Lin, H. Ren, and S. T. Wu, “Polarisation-independent liquid crystal devices,” Liquid Crystals Today17(1-2), 2–8 (2008).
[CrossRef]

H. Ren, Y. H. Lin, and S. T. Wu, “Polarization-independent and fast-response phase modulators using double-layered liquid crystal gels,” Appl. Phys. Lett.88(6), 061123 (2006).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Wu, Y. Zhao, J. Y. Fang, Z. Ge, and S. T. Wu, “Polarization-independent liquid crystal phase modulator using a thin polymer-separated double-layered structure,” Opt. Express13(22), 8746–8752 (2005).
[CrossRef] [PubMed]

H. Ren, Y. H. Lin, Y. H. Fan, and S. T. Wu, “Polarization-independent phase modulation using a polymer-dispersed liquid crystal,” Appl. Phys. Lett.86(14), 141110 (2005).
[CrossRef]

H. Ren, Y. H. Lin, C. H. Wen, and S. T. Wu, “Polarization-independent phase modulation of a homeotropic liquid crystal gel,” Appl. Phys. Lett.87(19), 191106 (2005).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Fan, Y. H. Wu, and S. T. Wu, “Polarization-independent and fast-response phase modulation using a normal-mode polymer-stabilized cholesteric texture,” J. Appl. Phys.98(4), 043112 (2005).
[CrossRef]

H. Ren and S. T. Wu, “Inhomogeneous nanoscale polymer-dispersed liquid crystals with gradient refractive index,” Appl. Phys. Lett.81(19), 3537–3539 (2002).
[CrossRef]

Rol, P.

P. Rol, R. Jenny, D. Beck, F. Frankhauser, and P. F. Niederer, “Optical properties of miniatured endoscopes for ophthalmic use,” Opt. Eng.34(7), 2070–2077 (1995).
[CrossRef]

Sasian, J. M.

R. El-Maksoud, L. Wang, J. M. Sasian, and V. S. Valencia, “Depth of field estimation: theory, experiment, and application,” Proc. SPIE7429, 74290W, 74290W-12 (2009).
[CrossRef]

Sato, S.

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

B. Wang, M. Ye, and S. Sato, “Liquid crystal lens with focal length variable from negative to positive values,” IEEE Photon. Technol. Lett.18(1), 79–81 (2006).
[CrossRef]

Schwiegerling, J.

Seo, J. H.

S. W. Seo, S. Han, J. H. Seo, W. B. Choi, and M. Y. Sung, “Liquid lens module with wide field-of view and variable focal length,” Electronic Mater. Lett.6(4), 141–144 (2010).
[CrossRef]

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

Seo, S. W.

S. W. Seo, S. Han, J. H. Seo, W. B. Choi, and M. Y. Sung, “Liquid lens module with wide field-of view and variable focal length,” Electronic Mater. Lett.6(4), 141–144 (2010).
[CrossRef]

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

Simoni, F.

D. E. Lucchetta, R. Karapinar, A. Manni, and F. Simoni, “Phase-only modulation by nanosized polymer-dispersed liquid crystals,” J. Appl. Phys.91(9), 6060–6065 (2002).
[CrossRef]

Smith, C. T.

X. Zeng, C. T. Smith, J. C. Gould, C. P. Heise, and H. Jiang, “Fiber endoscopes utilizing liquid tunable-focus microlenses actuated through infrared light,” J. of Microelectromechannical Systems20(3), 583–593 (2011).
[CrossRef]

Su, W. K.

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (2008).
[CrossRef]

Sung, M. Y.

S. W. Seo, S. Han, J. H. Seo, W. B. Choi, and M. Y. Sung, “Liquid lens module with wide field-of view and variable focal length,” Electronic Mater. Lett.6(4), 141–144 (2010).
[CrossRef]

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

Takahashi, S.

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

Tsou, Y. S.

Y. H. Lin, M. S. Chen, W. C. Lin, and Y. S. Tsou, “A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degree twisted cell,” J. Appl. Phys.112(2), 024505 (2012).
[CrossRef]

Y. S. Tsou, Y. H. Lin, and A. C. Wei, “Concentrating Photovoltaic System Using a Liquid Crystal Lens,” IEEE Photon. Technol. Lett.24(24), 2239–2242 (2012).
[CrossRef]

Y. H. Lin and Y. S. Tsou, “A polarization independent liquid crystal phase modulation adopting surface pinning effect of polymer dispersed liquid crystals,” J. Appl. Phys.110(11), 114516 (2011).
[CrossRef]

Y. H. Lin, H. S. Chen, H. C. Lin, Y. S. Tsou, H. K. Hsu, and W. Y. Li, “Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals,” Appl. Phys. Lett.96(11), 113505 (2010).
[CrossRef]

Uchida, M.

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

Valencia, V. S.

R. El-Maksoud, L. Wang, J. M. Sasian, and V. S. Valencia, “Depth of field estimation: theory, experiment, and application,” Proc. SPIE7429, 74290W, 74290W-12 (2009).
[CrossRef]

Valley, P.

Wang, B.

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

B. Wang, M. Ye, and S. Sato, “Liquid crystal lens with focal length variable from negative to positive values,” IEEE Photon. Technol. Lett.18(1), 79–81 (2006).
[CrossRef]

Wang, L.

R. El-Maksoud, L. Wang, J. M. Sasian, and V. S. Valencia, “Depth of field estimation: theory, experiment, and application,” Proc. SPIE7429, 74290W, 74290W-12 (2009).
[CrossRef]

Wei, A. C.

Y. S. Tsou, Y. H. Lin, and A. C. Wei, “Concentrating Photovoltaic System Using a Liquid Crystal Lens,” IEEE Photon. Technol. Lett.24(24), 2239–2242 (2012).
[CrossRef]

Wen, C. H.

Y. Huang, C. H. Wen, and S. T. Wu, “Polarization-independent and submillisecond response phase modulators using a 90° twisted dual-frequency liquid crystal,” Appl. Phys. Lett.89(2), 021103 (2006).
[CrossRef]

H. Ren, Y. H. Lin, C. H. Wen, and S. T. Wu, “Polarization-independent phase modulation of a homeotropic liquid crystal gel,” Appl. Phys. Lett.87(19), 191106 (2005).
[CrossRef]

Wu, H. M.

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (2008).
[CrossRef]

Wu, S. T.

H. Ren, S. Xu, Y. Liu, and S. T. Wu, “Switchable focus using a polymeric lenticular microlens array and a polarization rotator,” Opt. Express21(7), 7916–7925 (2013).
[CrossRef] [PubMed]

Y. H. Lin, H. Ren, and S. T. Wu, “Polarisation-independent liquid crystal devices,” Liquid Crystals Today17(1-2), 2–8 (2008).
[CrossRef]

Y. Huang, C. H. Wen, and S. T. Wu, “Polarization-independent and submillisecond response phase modulators using a 90° twisted dual-frequency liquid crystal,” Appl. Phys. Lett.89(2), 021103 (2006).
[CrossRef]

H. Ren, Y. H. Lin, and S. T. Wu, “Polarization-independent and fast-response phase modulators using double-layered liquid crystal gels,” Appl. Phys. Lett.88(6), 061123 (2006).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Wu, Y. Zhao, J. Y. Fang, Z. Ge, and S. T. Wu, “Polarization-independent liquid crystal phase modulator using a thin polymer-separated double-layered structure,” Opt. Express13(22), 8746–8752 (2005).
[CrossRef] [PubMed]

H. Ren, Y. H. Lin, Y. H. Fan, and S. T. Wu, “Polarization-independent phase modulation using a polymer-dispersed liquid crystal,” Appl. Phys. Lett.86(14), 141110 (2005).
[CrossRef]

H. Ren, Y. H. Lin, C. H. Wen, and S. T. Wu, “Polarization-independent phase modulation of a homeotropic liquid crystal gel,” Appl. Phys. Lett.87(19), 191106 (2005).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Fan, Y. H. Wu, and S. T. Wu, “Polarization-independent and fast-response phase modulation using a normal-mode polymer-stabilized cholesteric texture,” J. Appl. Phys.98(4), 043112 (2005).
[CrossRef]

H. Ren and S. T. Wu, “Inhomogeneous nanoscale polymer-dispersed liquid crystals with gradient refractive index,” Appl. Phys. Lett.81(19), 3537–3539 (2002).
[CrossRef]

Wu, Y. H.

Y. H. Lin, H. Ren, Y. H. Fan, Y. H. Wu, and S. T. Wu, “Polarization-independent and fast-response phase modulation using a normal-mode polymer-stabilized cholesteric texture,” J. Appl. Phys.98(4), 043112 (2005).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Wu, Y. Zhao, J. Y. Fang, Z. Ge, and S. T. Wu, “Polarization-independent liquid crystal phase modulator using a thin polymer-separated double-layered structure,” Opt. Express13(22), 8746–8752 (2005).
[CrossRef] [PubMed]

Xu, S.

Yamaguchi, M.

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

Yanase, S.

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

Yang, M. Q.

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (2008).
[CrossRef]

Ye, M.

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

B. Wang, M. Ye, and S. Sato, “Liquid crystal lens with focal length variable from negative to positive values,” IEEE Photon. Technol. Lett.18(1), 79–81 (2006).
[CrossRef]

Zeng, X.

X. Zeng, C. T. Smith, J. C. Gould, C. P. Heise, and H. Jiang, “Fiber endoscopes utilizing liquid tunable-focus microlenses actuated through infrared light,” J. of Microelectromechannical Systems20(3), 583–593 (2011).
[CrossRef]

Zhao, Y.

Appl. Phys. Lett. (8)

H. C. Lin and Y. H. Lin, “A fast response and large electrically tunable-focusing imaging system based on switching of two modes of a liquid crystal lens,” Appl. Phys. Lett.97(6), 063505 (2010).
[CrossRef]

Y. H. Lin, H. S. Chen, H. C. Lin, Y. S. Tsou, H. K. Hsu, and W. Y. Li, “Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals,” Appl. Phys. Lett.96(11), 113505 (2010).
[CrossRef]

H. C. Lin and Y. H. Lin, “An electrically tunable focusing liquid crystal lens with built-in planar polymeric lens,” Appl. Phys. Lett.98(8), 083503 (2011).
[CrossRef]

H. Ren and S. T. Wu, “Inhomogeneous nanoscale polymer-dispersed liquid crystals with gradient refractive index,” Appl. Phys. Lett.81(19), 3537–3539 (2002).
[CrossRef]

H. Ren, Y. H. Lin, Y. H. Fan, and S. T. Wu, “Polarization-independent phase modulation using a polymer-dispersed liquid crystal,” Appl. Phys. Lett.86(14), 141110 (2005).
[CrossRef]

H. Ren, Y. H. Lin, C. H. Wen, and S. T. Wu, “Polarization-independent phase modulation of a homeotropic liquid crystal gel,” Appl. Phys. Lett.87(19), 191106 (2005).
[CrossRef]

Y. Huang, C. H. Wen, and S. T. Wu, “Polarization-independent and submillisecond response phase modulators using a 90° twisted dual-frequency liquid crystal,” Appl. Phys. Lett.89(2), 021103 (2006).
[CrossRef]

H. Ren, Y. H. Lin, and S. T. Wu, “Polarization-independent and fast-response phase modulators using double-layered liquid crystal gels,” Appl. Phys. Lett.88(6), 061123 (2006).
[CrossRef]

Electronic Mater. Lett. (1)

S. W. Seo, S. Han, J. H. Seo, W. B. Choi, and M. Y. Sung, “Liquid lens module with wide field-of view and variable focal length,” Electronic Mater. Lett.6(4), 141–144 (2010).
[CrossRef]

IEEE Photon. Technol. Lett. (2)

B. Wang, M. Ye, and S. Sato, “Liquid crystal lens with focal length variable from negative to positive values,” IEEE Photon. Technol. Lett.18(1), 79–81 (2006).
[CrossRef]

Y. S. Tsou, Y. H. Lin, and A. C. Wei, “Concentrating Photovoltaic System Using a Liquid Crystal Lens,” IEEE Photon. Technol. Lett.24(24), 2239–2242 (2012).
[CrossRef]

J. Appl. Phys. (4)

Y. H. Lin and Y. S. Tsou, “A polarization independent liquid crystal phase modulation adopting surface pinning effect of polymer dispersed liquid crystals,” J. Appl. Phys.110(11), 114516 (2011).
[CrossRef]

Y. H. Lin, M. S. Chen, W. C. Lin, and Y. S. Tsou, “A polarization-independent liquid crystal phase modulation using polymer-network liquid crystals in a 90 degree twisted cell,” J. Appl. Phys.112(2), 024505 (2012).
[CrossRef]

Y. H. Lin, H. Ren, Y. H. Fan, Y. H. Wu, and S. T. Wu, “Polarization-independent and fast-response phase modulation using a normal-mode polymer-stabilized cholesteric texture,” J. Appl. Phys.98(4), 043112 (2005).
[CrossRef]

D. E. Lucchetta, R. Karapinar, A. Manni, and F. Simoni, “Phase-only modulation by nanosized polymer-dispersed liquid crystals,” J. Appl. Phys.91(9), 6060–6065 (2002).
[CrossRef]

J. of Microelectromechannical Systems (1)

X. Zeng, C. T. Smith, J. C. Gould, C. P. Heise, and H. Jiang, “Fiber endoscopes utilizing liquid tunable-focus microlenses actuated through infrared light,” J. of Microelectromechannical Systems20(3), 583–593 (2011).
[CrossRef]

Jpn. J. Appl. Phys. (3)

M. Ye, B. Wang, M. Uchida, S. Yanase, S. Takahashi, M. Yamaguchi, and S. Sato, “Low-voltage-driving liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 100204 (2010).
[CrossRef]

S. W. Seo, S. Han, J. H. Seo, Y. M. Kim, M. S. Kang, N. K. Min, W. B. Choi, and M. Y. Sung, “Microelectromechanical-system-based variable-focus liquid lens for capsule endoscopes,” Jpn. J. Appl. Phys.48(5), 052404 (2009).
[CrossRef]

H. C. Lin and Y. H. Lin, “An electrically tunable focusing pico-projector adopting a liquid crystal lens,” Jpn. J. Appl. Phys.49(10), 102502 (2010).
[CrossRef]

Liquid Crystals Today (1)

Y. H. Lin, H. Ren, and S. T. Wu, “Polarisation-independent liquid crystal devices,” Liquid Crystals Today17(1-2), 2–8 (2008).
[CrossRef]

Opt. Eng. (1)

P. Rol, R. Jenny, D. Beck, F. Frankhauser, and P. F. Niederer, “Optical properties of miniatured endoscopes for ophthalmic use,” Opt. Eng.34(7), 2070–2077 (1995).
[CrossRef]

Opt. Express (6)

Opt. Lett. (1)

Proc. SPIE (3)

R. El-Maksoud, L. Wang, J. M. Sasian, and V. S. Valencia, “Depth of field estimation: theory, experiment, and application,” Proc. SPIE7429, 74290W, 74290W-12 (2009).
[CrossRef]

S. Kuiper, “Electrowetting-based liquid lenses for endoscopy,” Proc. SPIE7930, 793008, 793008-8 (2011).
[CrossRef]

M. Q. Yang, S. W. Huang, W. K. Su, H. M. Feng, Z. Y. Chen, H. M. Wu, and Y. T. Kuo, “Optimizing the depth of field for short object distance of capsule endoscope,” Proc. SPIE6859, 68591Q, 68591Q-7 (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 (4)

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

H. Gross, H. Zugge, M. Peschka, and F. Blechinger, Handbook of Optical Systems: Aberration Theory and Correction of Optical Systems (WILEY-VCH, 2007, Vol. 3).

H. S. Chen and Y. H. Lin, “An electrically tunable endoscopic system by adding a liquid crystal lens to enlarge and shift depth-of field,” SPIE8828 (2013).

M. Katz, Introduction to Geometrical Optics (World Scientific Publishing Co. Pte. Ltd., 2002).

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Figures (6)

Fig. 1
Fig. 1

(a)The illustration of the endoscopic system adopting a LC lens. The white arrow is the transmissive axis of the polarizer.(b)The structure of the LC lens in (a). When V2 = V1 = 0, lens power of the LC lens is zero. When V1>V2, the LC lens is a positive lens and the lens power is positive. When V2>V1, the LC lens is a negative lens and the lens power is negative.

Fig. 2
Fig. 2

Phase profile of the LC lens. (a) The LC lens is the negative lens at V1 = 0, V2 = 45 Vrms. (b) The LC lens is the positive lens at V1 = 90 Vrms, V2 = 0.(c) Lens power as a function of applied voltage. Black dots stand for the lens power as a function of applied voltage V2 at V1 = 90 Vrms. Red triangles stand for the lens power as a function of applied voltage V1 at V2 = 45 Vrms.

Fig. 3
Fig. 3

The contrast as a function of the objective distance at (V1 = 0Vrms, V2 = 0Vrms) depicted as red dots, at (V1 = 90Vrms,V2 = 0Vrms) depicted as black squares, and at(V1 = 0Vrms,V2 = 45Vrms) depicted as green triangles. The lens powers of the LC lens at (V1 = 0Vrms, V2 = 0Vrms), (V1 = 90Vrms,V2 = 0Vrms), and (V1 = 0Vrms,V2 = 45Vrms) are 0, 19.9D, and −12.4D, respectively.

Fig. 4
Fig. 4

Objective distance as a function of LC lens power when the contrast is maximum (black dots). Blue triangles and red squares represent the near objective distance and far objective distance when the contrast is half of maximum contrast. Grey dotted line stands for the theoretical prediction for the maximum contrast according to Eq. (1).

Fig. 5
Fig. 5

DOF as a function of LC lens power for the experiments (red squares) and theoretical prediction (black line). DOF is defined as the difference between the near objective distance and far objective distance in Fig. 4.

Fig. 6
Fig. 6

The image performances of the endoscopic system. (a)The lens power of the LC lens is zero and the DOF δ1 = 30 mm. The objective distance is from 57mm ~27mm. (b) The lens power of the LC lens is + 19.9 D and the DOF δ2 = 14.6 mm. The objective distance is from 27mm ~12.4mm. (c) The lens power of the LC lens is −12.4 D and the DOF δ3 = 38.8 mm. The objective distance is from 76.4mm ~37.6mm.

Equations (7)

Equations on this page are rendered with MathJax. Learn more.

u(V)= 1 P LC (V)+P sys ,
P sys = 1 d 1 n + 1 P s 1 d 2 ,
δ(V)= 2×B×(u(V)q)× D s ' D s ' 2 B 2 ,
δ(V) 2B×(u(V)q) ( q n × d 1 )× D s 2×n×B d 1 × D s ×( u(V) q 1).
δ(V)B×u(V)= B P LC (V)+P sys .
P LC (V)= 2Nλ r 2 ,
C= I max I min I max + I min ,

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