Browsing by Author "Lin, Hung-Chun"

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A fast response and large electrically tunable-focusing imaging system based on switching of two modes of a liquid crystal lens
(2010-08-09)
Lin, Hung-Chun
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
We demonstrated a fast response and large tunable focusing imaging system consisting of a lens module and a liquid crystal (LC) lens based on the switching of two modes of a LC lens: the negative LC lens and positive LC lens. By discarding the conventional operation of a positive LC lens only in the imaging system, large tunable focusing range can be achieve from 300 to 10 cm owning to the phase change between the positive and the negative LC lens; meanwhile, the response time is fast (similar to 433 ms). The potential applications are autofocused cell phones, and cameras. (C) 2010 American Institute of Physics. [doi:10.1063/1.3479051]
A Holographic Projection System With an Electrically Adjustable Optical Zoom and a Fixed Location of Zeroth-Order Diffraction
(2014-06-01)
Chen, Ming-Syuan
;
Collings, Neil
;
Lin, Hung-Chun
;
Lin, Yi-Hsin
;
光電工程學系
An electrically tunable optical zooming holographic projection system with a fixed location of zeroth-order diffraction is demonstrated. By using two liquid lenses and an encoded Fresnel lens on a liquid crystal on silicon (LCoS) panel, the size of the projected image of the holographic projection system is changeable; meanwhile, the locations of both of the zeroth-order diffraction and the first-order diffraction are unchanged. Therefore, the zeroth-order diffraction can be removed by using a fixed optical high-pass filter. We can use it to realize an image size matching system for green light (532 nm) and red light (632.8 nm) without any positional motion of the optical elements. The optical zoom function enhances the feasibility to realize a high-resolution full-color holographic projection system.
A holographic projection system with an electrically tuning and continuously adjustable optical zoom
(2012-12-03)
Lin, Hung-Chun
;
Collings, Neil
;
Chen, Ming-Syuan
;
Lin, Yi-Hsin
;
光電工程學系
A holographic projection system with optical zoom is demonstrated. By using a combination of a LC lens and an encoded Fresnel lens on the LCoS panel, we can control zoom in a holographic projector. The magnification can be electrically adjusted by tuning the focal length of the combination of the two lenses. The zoom ratio of the holographic projection system can reach 3.7:1 with continuous zoom function. The optical zoom function can decrease the complexity of the holographic projection system. (c) 2012 Optical Society of America
A Polarizer-Free Electro-Optical Switch Using Dye-Doped Liquid Crystal Gels
(2009-12-01)
Lin, Yi-Hsin
;
Lin, Hung-Chun
;
Yang, Jhih-Ming
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光電工程學系
;
Department of Photonics
We demonstrate a polarizer-free electro-optical switch using dye-doped liquid crystal (LC) gels. The mechanism of dye-doped LC gels mainly involves the combination of polymer scattering and dye absorption. However, the domain size of polymer networks, dye concentration, LC concentration, and fabrication process can all affect the phase separation process and thus result in dye-doped LC gels with different electro-optical performance. We have studied experimentally the factors which can affect the dye-doped LC gels. The potential applications for dye-doped LC gels are flexible displays and electrically tunable light shutters.
A Reflective Polarizer-free Display Using a Droplet Manipulation on a Liquid Crystal and Polymer Composite Film
(2009)
Lin, Yi-Hsin
;
Lin, Hung-Chun
;
Li, Jiong-Kuan
;
Hsu, Hsu-Kuan
;
Li, Wang-Yang
A polarizer-free display using a droplet manipulation on a liquid crystal and polymer composite film (LCPCF) is demonstrated. Because of the electrically tunable orientation of the liquid crystal directors anchored among the polymer grains, the wettability of the LCPCF changes with an applied in-planed electric field. As a result, we can realize a reflective polarizer-free display when the colored droplet on the top of the LCPCF is manipulated by an inhomogeneous electric field. The contrast ratio is around 9:1 and the response time is around 900 ms.
An electrically tunable focusing liquid crystal lens with a built-in planar polymeric lens
(2011-02-21)
Lin, Hung-Chun
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
An electrically tunable focusing liquid crystal (LC) lens with a built-in planar polymeric lens with a short focal length (similar to 4.41 to 8.82 cm) is demonstrated. The focal length of the LC lens is contributed by two parts: one is the LC layer and the other is planar polymeric layer. In the image system, the object can be continuously imaged by the LC lens when the object is at the objective distance from 360 to 17 cm as the voltage is switched from 0 to 35 V(rms). The image performance is also demonstrated. The applications are cell phones, and cameras (C) 2011 American Institute of Physics. [doi: 10.1063/1.3559622]
AN ELECTRICALLY TUNABLE FOCUSING PICO PROJECTION SYSTEM BASED ON A LIQUID CRYSTAL LENS ADOPTING A LIQUID CRYSTAL AND POLYMER COMPOSITE FILM
(2011-12-01)
Lin, Hung-Chun
;
Chen, Ming-Syuan
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
An electrically tunable liquid-crystal-on-silicon (LCOS)-based pico projection system based on a liquid crystal lens adopting a liquid crystal and polymer composite film (LCPCF) is demonstrated. The LC lens consists of two built-in sub-lenses: one is an electrically tunable focusing lens controlled by a LC layer and the other is a fixed focused LCPCF lens. The electrically tunable focusing range of the pico projection system is 200 cm to similar to 7 cm when the voltage is from 0 to 35 V-rms. The image performance is also demonstrated. The related optical analysis is discussed. This study opens a new window for electrically tunable focusing pico projection system.
An Electrically Tunable Focusing Pico-Projector Adopting a Liquid Crystal Lens
(2010)
Lin, Hung-Chun
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
An electrically tunable pico-projector adopting a liquid crystal (LC) lens as an active optical element is demonstrated. The focal length of this pico-projector is electrically tunable from 350 to 14 cm and the tunable range is even wider than that of a manually focused pico-projector. The response times of turn-on and turn-off are approximately 313 and 880 ms, respectively. In addition, the location of the projection lens can affect the electrically tunable range of the system. A small shift of the projection lens results in the large tunable focusing range of the pico-projector and a tunable focusing range is determined by the LC lens. The optical analysis is also discussed. This concept can even be applied to design other electrically auto focusing pico-projectors based on other optical elements such as liquid lenses and spatial light modulators. (C) 2010 The Japan Society of Applied Physics
An electrically tunable LCOS pico projector with optical zoom
(2011)
Chen, Ming-Syuan
;
Lin, Hung-Chun
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
An electrically tunable zooming LCOS pico projector using composite liquid crystal (LC) lenses is demonstrated. The composite LC lens consists of two built-in sub-lenses: one is an electrically tunable focusing lens controlled by a LC layer and the other is a fixed focused polymeric lens. The zoom ratio of the electrically tunable zooming pico projector can reach 2.5 : 1 when the screen distance at 20 cm. The tunable focusing ranges are 200 cm to similar to 10 cm and the response times is around 3.8 sec. The image performance of the electrically tunable focusing LCOS pico projector is also demonstrated.
An electrically tunable optical zoom system using two composite liquid crystal lenses with a large zoom ratio
(2011-02-28)
Lin, Yi-Hsin
;
Chen, Ming-Syuan
;
Lin, Hung-Chun
;
光電工程學系
;
Department of Photonics
An electrically tunable-focusing optical zoom system using two composite LC lenses with a large zoom ratio is demonstrated. The optical principle is investigated. To enhance the electrically tunable focusing range of the negative lens power of the LC lens for a large zoom ratio, we adopted two composite LC lenses. Each composite LC lens consists of a sub-LC lens and a planar polymeric lens. The zoom ratio of the optical zooming system reaches similar to 7.9:1 and the object can be zoomed in or zoomed out continuously at the objective distance of infinity to 10 cm. The potential applications are cell phones, cameras, telescope and pico projectors. (C) 2011 Optical Society of America
An electrically tunable-focusing liquid crystal lens with a low voltage and simple electrodes
(2012-01-30)
Lin, Hung-Chun
;
Lin, Yi-Hsin
;
光電工程學系
;
Department of Photonics
An electrically tunable focusing LC lens with a low voltage and simple planar electrodes is demonstrated. The inhomogeneous electric field of the LC lens without any hole-patterned-electrode is generated by using an embedded polymeric layer with a gradient distribution of dielectric constants (or relative permittivity). LC directors in the LC layer experience spatially inhomogeneous voltages even though a single voltage is applied to the planar electrodes. Such a LC lens has a low voltage (similar to 2.6 V-rms) and simple design of electrodes. The gradient distribution of dielectric constants of polymeric layer is discussed and the performance of the LC lens is investigated. The applications of such a LC lens are cell phones, webcam, and pico projectors. (C)2012 Optical Society of America
Electrically tunable wettability of liquid crystal/polymer composite films
(2008-10-27)
Lin, Yi-Hsin
;
Ren, Hongwen
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Wu, Yung-Hsun
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Wu, Shin-Tson
;
Zhao, Yue
An electrically tunable wettability in a liquid crystal/polymer composite film is demonstrated, in which liquid crystal molecules are anchored among polymer grains. The tunable wettability of the composite films originates from the reorientation of the anchored liquid-crystal molecules, which is switched by an in-plane electric field with squared pulses of voltages. These liquid crystal/polymer composite films with electrically tunable wettability have potential applications in polarizer-free displays, ink-jet printing, microfluidic devices, and lab-on-a-chip. (C) 2008 Optical Society of America
Electrically-tunable optical zoom system by using liquid crystal lenses
(2012)
Lin, Yi-Hsin
;
Chen, Ming-Syuan
;
Lin, Hung-Chun
;
光電工程學系
;
Department of Photonics
An electrically-tunable optical zoom system using liquid crystal (LC) lenses is demonstrated. The mechanism of the optical zoom system is to use two lenses and a camera system to achieve focusing and zooming function. In this paper, we analyzed the imaging conditions and the magnification of the optical zoom system. The relation between the focusing properties of LC lenses and zoom ratio of the optical zoom system is also discussed. The electrically-tunable optical zoom system using two LC lenses has high zoom ratio (similar to 7.9: 1 to similar to 5.5:1), short system length (<10 cm) and the object can be zoomed in or zoomed out continuously at the objective distance of infinity to 10 cm. The potential applications are cell phones, cameras, telescopes and pico projectors.
Polarizer-free and fast response microlens arrays using polymer-stabilized blue phase liquid crystals
(2010-03-15)
Lin, Yi-Hsin
;
Chen, Hung-Shan
;
Lin, Hung-Chun
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Tsou, Yu-Shih
;
Hsu, Hsu-Kuan
We demonstrate polarizer-free and fast response microlens arrays based on optical phase modulation of polymer-stabilized blue phase liquid crystal (PSBP-LC). Polarization-independent optical phase shift is because the propagation of an incident light is along the optic axis of PSBP-LC, and birefringence of PSBP-LC induced by Kerr effect results in electrically tunable optical phase shift. The measured optical phase shift of a PSBP-LC phase modulation is around pi radian at 150 V(rms) for the cell gap of 7 mu. The response time is about 3 ms. The focal length is around 13.1 cm at 100 V(rms).
Thermally induced light leakage in in-plane-switching liquid crystal displays
(2009-02-01)
Hsu, Jy-Shan
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Lin, Yi-Hsin
;
Lin, Hung-Chun
;
Yang, Kei-Hsiung
;
光電工程學系
In this paper, we report the thermally induced light leakage in in-plane-switching liquid crystal displays (IPS LCDs) that have a built-in small-angle deviation (< 4 deg) between the polarization axis of a polarizer and the rubbing directions for liquid crystal (LC) alignment. We have found that the thermally induced light leakage depends strongly on the phase retardation which is a function of cell gap, wavelength, and birefringence of LCs used in the IPS LC cells. In addition, we have measured the light leakage of vertically aligned LC cells, which is independent of temperature and the deviation angle. A temperature-scanning method is proposed to reduce the light leakage of the IPS LCDs.
Tunable liquid crystal lens for a holographic projection system
(2013-01-01)
Collings, Neil
;
Lin, Yi-Hsin
;
Lin, Hung-Chun
;
Chen, Ming-Syuan
;
光電工程學系
The tunable liquid crystal (LC) lens designed for a holographic projection system is demonstrated. By using a single patterned electrode LC lens, a solid lens and an encoded Fresnel lens on the LCoS panel, we can maintain the image size of the holographic projector with different wavelengths (lambda: 674nm, 532nm and 445nm). The zoom ratio of the holographic projection system depends on the lens power of the solid lens and the tunable lens power of the LC lens. The optical zoom function can help to solve the image size mismatching problem of the holographic projection system.
Twisted Nematic Liquid-Crystal-Based Terahertz Phase Shifter using Pristine PEDOT: PSS Transparent Conducting Electrodes
(2019-02-02)
Sahoo, Anup Kumar
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Yang, Chan-Shan
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Yen, Chun-Ling
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Lin, Hung-Chun
;
Wang, Yu-Jen
For this study, we demonstrated three different types of twisted nematic (TN) liquid crystal (LC) terahertz (THz) phase shifters using pristine poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) thin films as transparent conducting electrodes (TCEs). The transmittance of spin-coated pristine PEDOT: PSS thin film was as high as 92% in the frequency range of 0.2-1.2 THz. This is among the highest reported. Several TN-LC cells were constructed in a comparative study, which confirmed the reliability of pristine PEDOT: PSS as a TCE layer for THz phase shifter applications. The highest phase shift, required root-mean-square (RMS) driving voltage, and threshold voltage achieved by devices tested were 95.2 degrees at 1 THz, 7.2 V-RMS, and 0.5 V-RMS, respectively. The thickness of the LC layer for the phase shifter was 250 mu m, approximately half as thick as previous designs. In addition, the pristine PEDOT: PSS-based TN-LC phase shifter exhibited a figure-of-merit (FOM) value of approximately 6.65 degree.dB(-1).V-1. This compared favorably with previously reported homogeneously aligned phase shifters with an FOM of 2.19 degree.dB(-1).V-1. Our results indicated that a twisted nematic LC cell with pristine PEDOT: PSS thin films as electrodes is a good combination for a THz phase shifter and wave plates as well as other LC-based THz devices.