Browsing by Author "Hsu, Ken-Yuh"

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A time-delay calibrated method for cornea hysteresis and intraocular pressure measurement
(2016-04-01)
Wang, Kuo-Jen
;
Tsai, Che-Liang
;
Wang, Wai
;
Hsu, Long
;
Hsu, Ken-Yuh
The presence of cornea hysteresis (CH) in characterizing the intraocular pressure (IOP) of a human eye deteriorates the accuracy of IOP. To suppress CH, the pressure gauge of a tonometer must be located as close as possible to the cornea. However, this arrangement is unpractical because appropriate working distance to the cornea is required. In this paper, a time-delay calibrated (TDC) method is proposed to counteract the undesired effect of CH in characterizing the IOP. Employing this TDC method, the CH approaches to zero for most eyes measured.
A time-delay calibrated method for cornea hysteresis and intraocular pressure measurement
(2016-04)
Wang, Kuo-Jen
;
Tsai, Che-Liang
;
Wang, Wai
;
Hsu, Long
;
Hsu, Ken-Yuh
The presence of cornea hysteresis (CH) in characterizing the intraocular pressure (IOP) of a human eye deteriorates the accuracy of IOP. To suppress CH, the pressure gauge of a tonometer must be located as close as possible to the cornea. However, this arrangement is unpractical because appropriate working distance to the cornea is required. In this paper, a time-delay calibrated (TDC) method is proposed to counteract the undesired effect of CH in characterizing the IOP. Employing this TDC method, the CH approaches to zero for most eyes measured.
An easier way to improvement the trapping performance of optical tweezers by donut-shaped beam
(2010)
Tsai, Che-Liang
;
Huang, Hang-Ping
;
Hsu, Long
;
Hsu, Ken-Yuh
;
光電工程學系
In optical tweezers, it can be comprehended that the larger the inclination angle between the condensed laser beam and the optical axis contributes more to axial trapping force, while the central part of laser beam with smaller inclination angle contributes more transverse trapping force. Therefore donut-shaped beam is used to improve the problem of less-axial trapping for common optical tweezers. Some research reports have shown that the efficiency of a trapping force can be enhanced by using a donut-shaped beam. In this paper we present the dependence of the axial and the transverse components of a trapping force on the configuration of a focused donut-shaped beam. The simulation result will provide a simple and easy guide for optical tweezers users to adjust the configuration of a focused donut-shaped beam for optimal trapping performance.
An in situ fabrication process for highly electrical conductive polyimide/MWCNT composite films using 2,6-diaminoanthraquinone
(2013-10-18)
Huang, Yi-Chia
;
Lin, June-Hua
;
Tseng, I-Hsiang
;
Lo, An-Ya
;
Lo, Teng-Yuan
We present a valuable in situ fabrication process for synthesizing high electrical conductive polyimide/multiwalled carbon nanotube (PI/MWCNT) composite films. The success of this process was achieved the addition of 2,6-diaminoanthraquinone (DAAQ). The DAAQ is not only an excellent dispersion agent to stably disperse pristine MWCNTs in solvent but also a monomer to directly synthesize PI. The strong interaction between DAAQ with MWCNT was verified by FTIR, UV-Vis, Raman, and fluorescence spectra. The highest value of electrical conductivity of 55.6 S/cm are achieved by the PI composite containing 40 wt.% of MWCNT. Moreover, the electrical conductivity of this film further enhanced to 106 S/cm after the thermal compression process. The MWCNT content at the percolation threshold of conductivity is 0.50 wt.% (or 0.32 vol.%) and the critical exponent is equal to 2.52. The developed in situ fabrication process through DAAQ-derived molecules can also be applied to synthesize other polymers requiring diamine structure. (C) 2013 Published by Elsevier Ltd.
Broadband Microspectrophotometer with Tablet PC Control
(2012)
Weng, Chun-Jen
;
Hsu, Ken-Yuh
;
Chen, Yung-Fu
;
Chang, Shian-Wen
;
Cho, Wen-Hao
This study investigated the design, fabrication, and performance characterizations of a broadband microspectrophotometer with tablet PC wireless control. The microspectrophotometer system performed rapid measurements, was highly accurate, and was easy to operate. The calibrations for two measurement modes for transmittance and reflectance spectra were performed with bulk and multilayer thin-film samples. Objective lenses with various magnifications were introduced to verify the possibility of microscopic spectra measurements in the system. A polarization identification capability was also included in the system.
Compact motorized circular wheel of polarization optics for ultra-broadband polarization state generation
(2012)
Weng, Chun-Jen
;
Liu, Da-Ren
;
Hsu, Ken-Yuh
;
Chen, Yung-Fu
;
光電工程學系
This study proposes an innovative optical mechanism with a miniature motorized circular wheel for polarization optics for an ultra-broadband polarization state generator. The proposed apparatus can be suitable for a polarimetric microspectrophotometer for measurements of micro optics and metamaterials with circular dichroism and linear dichroism. Different types of micro optics have their own wavelength dependence, meaning different curves in the broadband range of light. This study presents an ultra-broadband platform for measuring and identifying micro optics such as chiral metamaterials, plasmonics, micro polarizers, and patterned retarders. The key component of a polarimetric microspectrophotometer is a polarization state generator (PSG). A simple PSG consists of a polarizer and a waveplate. An arbitrary polarization state can be created by rotating either the polarizer or the waveplate. Sheet polarizers and achromatic waveplates have a limited bandwidth range. For the ultra-broadband measurement range of 400 nm to 1700 nm, the PSG needs at least three sheet polarizers and three achromatic waveplates: 400 nm-700 nm, 700 nm-1000 nm, and 1000 nm-1700 nm. This optical mechanism, which consists of only one control motor and two high precision unidirectional bearings, includes several polarizers and waveplates arranged in a matrix on a circular wheel. This apparatus can shift one of the polarizers and waveplates to a predetermined position and rotate all the polarizers to change the polarization status. An ultra-broadband polarimetric microspectrophotometer with a compact motorized wheel is an advanced polarization optical instrument for research on chiral metamaterials, plasmonics, micro polarization optics, green optics, and bio optics.
Confocal displacement sensor with varifocal lens
(2015)
Weng, Chun-Jen
;
Lan, Tzu-Hsien
;
Hwang, Chi-Hung
;
Liu, Da-Ren
;
Chen, Chih-Yen
a confocal displacement sensor with a varifocal lens and a multi-wavelength rainbow laser was established in this study. The surface curvature of varifocal lens was varied by different current driving so that the focal length can be easily changed. Thus, we can quickly measure the distance between the sensor head and targets by detecting the reflective power according to the principle of confocal laser. This rainbow laser can operate at four different wavelengths. The laser beams with different colors can be used to measure the dispersion of varifocal lens. The range of measuring displacement with 20X objective lens in this displacement sensor is from 4.9mm to 5.9mm. The FWHM resolution of displacement is about 70 mu m. The step-height aluminate plate was measured by this system and the error of measuring distance is less than 35 mu m (0.75%).
Developing a microspectrophotometer to measure the dependence of broadband refractive indices on Ge-doped concentrations in GRIN rods
(2015-11-30)
Weng, Chun-Jen
;
Hsu, Ken-Yuh
;
Lee, Cheng-Yeh
;
Chen, Yung-Fu
;
電子物理學系
A confocal microspectrophotometer is utilized to scan the surface reflectivities of a polished gradient-index (GRIN) rod in the range of 400 to 900 nm. The pure fused silica is used to be a reference standard for deducing the absolute reflectivities of the Ge-doped core. Then, multi-wavelength refractive index profiles of the Ge-doped core can be further determined based on the Fresnel equation. Moreover, this work shows a connection between the material dispersion of the GRIN rod and the Gedoped concentrations measured by an energy dispersive spectrometer. Finally, the dependence of the refractive index of the Ge-doped core on the doping concentrations at a certain wavelength can be easily expressed as a linear form. (c) 2015 Optical Society of America
Exploiting the image of the surface reflectivity to measure refractive index profiling for various optical fibers
(2015-05-04)
Weng, Chun-Jen
;
Hsu, Ken-Yuh
;
Chen, Yung-Fu
;
電子物理學系
;
光電工程學系
A direct image method of surface reflectivities on a cleaved fiber end with a filtered halogen lamp and a TE-cooled CCD with high dynamic range is proposed to measure the multi-wavelength refractive index profiling (RIP). A polished black glass is used to be a reference standard for measuring the absolute reflectivity of the fiber end. With the developed calibration procedures, both the spatially dependent sensitivity and spectral responsivity of the CCD pixels can be eliminated to achieve the high spatial accuracy. Tested fiber is connected with a fiber terminator to prevent errors from the backside return light. With the present method, the RIP can be precisely measured for not only multi-mode fibers but also single-mode fibers. (C) 2015 Optical Society of America
Holographic information recording and reproducing apparatus for the same
(2009-05-14)
Hsieh, Mei-Li
;
Lin, Shiuan-Huei
;
Wang, Jui-Hsin
;
Hsu, Ken-Yuh
;
Chiang, Don-Yau
In a holographic information recording and reproducing apparatus, an optical fiber guides a reference beam toward a recording medium for holographic recording, and a precision rotator is turned, so that the reference beam is incident on the recording medium at different angles and interferes with a data-carrying signal beam to complete the recording of holographic information on the recording medium. To reproduce the holographic information, the optical fiber guides a reading beam, and the reading beam is incident on the recording medium at an angle the same as the reference beam for the recording to reproduce the holographic information stored on the recording medium. With the optical fiber and the precision rotator, a simplified light path system and a wide range of incident angles for the reference and reading beams may be achieved, and the transmissive, reflective, and 90-degree holographic storage techniques may be integrated in one single apparatus.
Lasing action in gallium nitride photonic quasicrystal nanorod arrays
(2012)
Chang, Shih-Pang
;
Sou, Kuok-Pan
;
Chang, Jet-Rung
;
Cheng, Yuh-Jen
;
Li, Yuh-Jing
We report the observation of lasing action from optically pumped gallium nitride nanorod arrays in a quasicrystal pattern. The nanorods were fabricated from a GaN substrate by nanoimprint patterned etching, followed by epitaxial regrowth to form crystalline facets. The imprint was a 12-fold symmetric quasicrystal pattern. The regrowth grew a multiple quantum well core-shell structure on nanorods. The cathodoluminescent emission of quantum wells red shifts from the bottom to top region of nanorod. Under optical pumping, multiple lasing peaks were observed. The lasing modes formed by 12-fold symmetric photonic quasicrystal nanorod arrays are discussed.
Low efficiency droop of InGaN/GaN blue LEDs with super-lattice active structure
(2012)
Chang, Shih-Pang
;
Sou, Kuok-Pan
;
Chang, Jet-Rung
;
Cheng, Yuh-Jen
;
Li, Yuh-Jing
We report the efficiency droop behaviors of InGaN/GaN blue LEDs with different thickness of GaN quantum barriers (QBs). The droop percentage from efficiency peak to 70 A/cm(2) is only about 10% as reducing the thickness of GaN QBs from 104 angstrom to 33 angstrom. A less carrier localization has been observed from wavelength dependent time resoled photoluminescence measurement as reducing the thickness of GaN QBs. The alleviation of droop percentage may due to more uniform distribution of electron and hole carrier in the active region, which resulted from super-lattice (SL) like active structure. The crystalline quality does not become worse from the results of v-pits density even thickness of GaN QBs is as low as 33 angstrom. The SL like active structure could be a potential structure to alleviate the efficiency droop for the application of solid state general lighting.
Near-infrared sensitive organic-inorganic photorefractive device
(2016-10)
Marinova, Vera
;
Liu, Ren-Chung
;
Lin, Shiuan-Huei
;
Chen, Ming-Syuan
;
Lin, Yi-Hsin
Organic-inorganic hybrid structure, assembled by Rh-doped Bi12TiO20 crystal and liquid crystal (LC) layer, operating at near-infrared range is proposed and demonstrated. Due to the photorefractive properties of inorganic substrate, light illumination caused a space charge field which acts as a driving force for LC molecules re-alignment and subsequent refractive index modulation. All optically controlled phase retardation ability has been demonstrated supporting possibilities for further infrared applications.
Near-infrared sensitive organic-inorganic photorefractive device
(2016-10-01)
Marinova, Vera
;
Liu, Ren-Chung
;
Lin, Shiuan-Huei
;
Chen, Ming-Syuan
;
Lin, Yi-Hsin
Organic-inorganic hybrid structure, assembled by Rh-doped Bi12TiO20 crystal and liquid crystal (LC) layer, operating at near-infrared range is proposed and demonstrated. Due to the photorefractive properties of inorganic substrate, light illumination caused a space charge field which acts as a driving force for LC molecules re-alignment and subsequent refractive index modulation. All optically controlled phase retardation ability has been demonstrated supporting possibilities for further infrared applications.
Optimization of holographic data storage system based on Seidel aberrations reduction
(2015-01-01)
Liu, Ren-Chung
;
Lin, Shiuan-Huei
;
Hsu, Ken-Yuh
;
電子物理學系
;
光電工程學系
In this research, we investigate the influence of Seidel aberrations on the point spread function and the probability density function of holographic data storage systems, and thus the storage capacity and bit error rate of storage system can be obtained. The aberrations tolerances of storage systems with different numerical aperture are obtained. Optimization on BER and SC of holographic data storage systems by reducing Seidel aberrations will be demonstrated numerically.
Prism-hologram-prism sandwiched recording method for polarization-selective substrate-mode volume holograms with a large diffraction angle
(2018-08-06)
Hsu, Fan-Hsi
;
Han, Chien-Yuan
;
Chen, Kun-Huang
;
Hsu, Ken-Yuh
;
Chen, Jing-Heng
We propose a prism-hologram-prism sandwiched recording method for the fabrication of polarization-selective substrate-mode volume holograms with a large diffraction angle. In fabrication, the C-RT20 photopolymer is sandwiched between two 45 degrees-90 degrees-45 degrees prisms and the interference fringes can be easily recorded in the recording material. The experimental results are in good agreement with the theoretical predictions. The proposed method features of a reflection-type recording setup for a transmission element and belongs to a technique of longer-wavelength construction for shorter-wavelength reconstruction. In addition, the method is much easier than the traditional recording method of two incident beam interference and has application potential in holographic photonics. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
Tunable Single-Pair Hollow-Beam-Converter Dark-Field Microscopy
(2013-10-01)
Tsai, Che-Liang
;
Hsu, Long
;
Huang, Kuang-Lung
;
Hsu, Ken-Yuh
;
電子物理學系
A tunable single-pair hollow-beam-converter (TSHBC) dark-field microscopy is proposed and fabricated. The TSHBC is composed of one pair of parallel reflective mirrors of complementary cone shape. By simply adjusting the longitudinal separation between the two mirrors of TSHBC, a dark-field image with more high contrast and high energy efficiency can be obtained for a given objective lens. Furthermore, the selection criteria of the condenser lens and objective lens are provided for the structure of an optimal dark-field microscopy with TSHBC. (C) 2013 The Japan Society of Applied Physics
Two-wavelength holographic recording in photopolymer using four-energy-level system: experiments and modeling
(2014-11-01)
Lin, Chun-Hua
;
Cho, Sheng-Lung
;
Lin, Shiuan-Huei
;
Chi, Sien
;
Hsu, Ken-Yuh
We investigate a two-wavelength method for recording a persistent hologram in a doped photopolymer. The recording method is based on two separated optical excitations of the four-energy-level system of the doped element, one at lambda = 325 nm as the sensitizing wavelength and the other at lambda = 647 nm as the writing wavelength, allowing for an experimental demonstration of nondestructive readout in phenanthrenequinone-doped poly(methyl methacrylate). Further, a four-energy-level rate equations model is proposed for describing the dynamics of hologram recording. The model successfully explains our experimental finding and further provides a general method to investigate such a two-wavelength holographic recording in photopolymer. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Two-wavelength holographic recording in photopolymer using four-energy-level system: experiments and modeling
(2014-11-01)
Lin, Chun-Hua
;
Cho, Sheng-Lung
;
Lin, Shiuan-Huei
;
Chi, Sien
;
Hsu, Ken-Yuh
We investigate a two-wavelength method for recording a persistent hologram in a doped photopolymer. The recording method is based on two separated optical excitations of the four-energy-level system of the doped element, one at lambda = 325 nm as the sensitizing wavelength and the other at lambda = 647 nm as the writing wavelength, allowing for an experimental demonstration of nondestructive readout in phenanthrenequinone-doped poly(methyl methacrylate). Further, a four-energy-level rate equations model is proposed for describing the dynamics of hologram recording. The model successfully explains our experimental finding and further provides a general method to investigate such a two-wavelength holographic recording in photopolymer. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.