Browsing by Author "Chigrinov, Vladimir Grigorievich"

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A large bistable negative lens by integrating a polarization switch with a passively anisotropic focusing element
(2014-06-02)
Chen, Hung-Shan
;
Lin, Yi-Hsin
;
Srivastava, Abhishek Kumar
;
Chigrinov, Vladimir Grigorievich
;
Chang, Chia-Ming
A bistable negative lens with a large aperture size (similar to 10mm) by integrating a polarization switch of ferroelectric liquid crystals (FLCs) with a passively anisotropic focusing element is demonstrated. The proposed lens not only exhibits electrically tunable bistability but also fast response time of sub-milliseconds. The tunable lens power is from 0 to -1.74 Diopters. The electro-optical properties and imaging performances are demonstrated. The impact of this study is to provide a solution of electrically bistable liquid crystal lenses for the applications of portable devices, wearable devices and colored ophthalmic lenses. (C) 2014 Optical Society of America
A polarized bifocal switch based on liquid crystals operated electrically and optically
(2015-01-28)
Chen, Hung-Shan
;
Lin, Yi-Hsin
;
Chang, Chia-Ming
;
Wang, Yu-Jen
;
Srivastava, Abhishek Kumar
A polarized bifocal switch based on liquid crystals (LC) operated electrically and optically is demonstrated. The bifocal switch mainly consists of two parts: a LC layer as a polarization switch and two polymeric layers for modulation of polarization dependent spatial phase difference which results in a positive or a negative lensing effect. The orientations of the LC molecules in the polarization switch are manipulated either in electrically switching (ES) mode or optically rewritten (ORW) mode. The bifocal switch with an aperture size of 10mm exhibits two discrete lens powers (-1.39 Diopter and +0.7 Diopter) with different polarization states no matter in ES mode or in ORW mode. ORW mode is also a bistable mode. The related mechanism and electro-optical performance are discussed and demonstrated. Such a versatile optical switch is capable of not only switching between a positive lens power and a negative lens power, but also switching between two linear polarization states which can be useful in optical systems. The potential applications are for optical systems, wearable devices and ophthalmic lenses. (C) 2015 AIP Publishing LLC.
A polarized liquid crystal lens with electrically switching mode and optically written mode
(2015-01-01)
Chen, Hung-Shan
;
Lin, Yi-Hsin
;
Chang, Chia-Ming
;
Wang, Yu-Jen
;
Srivastava, Abhishek Kumar
A polarized liquid crystal (LC) lens composed of a LC layers as a polarization switch and a liquid crystal and polymer composites lens (LCPC lens) is demonstrated with electrically switching (ES) mode and optically rewritten (ORW) mode. The lens power of LCPC lens is related to a polarization state of light modulated by the LC layer whose orientations are manipulated either electrically or optically. As a result, the LC lens is not only electrically switchable, but also optically rewritable. Each mode, ES mode or ORW mode, exhibits two discrete lens powers (-1.39 Diopter and +0.7 Diopter). The demonstrated aperture size is 10 mm. The detail optical mechanism is also discussed. The Modulation Transfer Function (so-called MTF) of the lens is measured as well. In addition, the image performance and the dispersion of the LC lens are investigated. Such a polarized LC lens could be a special switch in optical systems due to dual operation modes.
An optical system adopting liquid crystals with electrical tunability of wavelength and energy density for low level light therapy
(2015-01-01)
Chang, Chia-Ming
;
Wang, Yu-Jen
;
Chen, Hung-Shan
;
Lin, Yi-Hsin
;
Srivastava, Abhishek Kumar
We have developed a bistable negative lens by integrating a polarization switch of ferroelectric liquid crystals (FLCs) with a passively anisotropic focusing element. The proposed lens not only exhibits electrically tunable bistability but also fast response time of sub-milliseconds, which leads to good candidate of optical component in optical system for medical applications. In this paper, we demonstrate an optical system consisting of two FLC phase retarders and one LC lenses that exhibits both of electrically tunable wavelength and size of exposure area. The operating principles and the experimental results are discussed. The tunable spectrum, exposure area size and tunable irradiance are illustrated. Compared to conventional lenses with mechanical movements in the medical light therapy system, our electrically switchable optical system is more practical in the portable applications of light therapy (LLLT).
An optical system via liquid crystal photonic devices for photobiomodulation
(2018-03-09)
Chang, Chia-Ming
;
Lin, Yi-Hsin
;
Srivastava, Abhishek Kumar
;
Chigrinov, Vladimir Grigorievich
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光電工程學系
Photobiomodulation or low-level light therapy (LLLT) has extensive applications based on light-induced effects in biological systems. Photobiomodulation remains controversial because of a poorly understood biochemical mechanism limited by the well-known biphasic dose response or Arndt-Schulz curve. The Arndt-Schulz curve states that an optimal dose of light is a key factor for realizing a therapeutic effect. In this report, we demonstrate a tunable optical system for photobiomodulation to aid physicians in overcoming the constraints of light due to biphasic dose response. The tunable optical system is based on a white light-emitting diode and four liquid crystal (LC) photonic devices: three LC phase retarders, and one LC lens. The output light of the tunable optical system exhibits electrical tunability for the wavelength, energy density and beam size. The operating principle is introduced, and the experimental results are presented. The proposed concept can be further extended to other electrically tunable photonic devices for different clinical purposes for photobiomodulation.