Browsing by Author "Hsieh, ML"

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A hetero-associative memory using phase-multiplexing references
(2000-04-01)
Hsieh, ML
;
Hsu, KY
;
Lin, SH
;
電子物理學系
;
光電工程學系
We present a hetero-associative memory for multiple-associative pairs by using the phase-multiplexing technique. Two methods for reducing the cross-talk between different association pairs are proposed. An optical experiment for the edge-enhancement associative memory is also demonstrated. (C) 2000 Elsevier Science B.V. All rights reserved.
Color image recognition by use of a joint transform correlator of three liquid-crystal televisions
(2002-03-10)
Hsieh, ML
;
Hsu, KY
;
Zhai, HC
;
光電工程學系
;
Department of Photonics
We present a joint transform correlator for color image recognition by using three liquid-crystal spatial light modulators. A method for simultaneously obtaining the correlation peaks of red, green, and blue is proposed and experimentally demonstrated. (C) 2002 Optical Society of America.
Effect of grating detuning on volume holographic memory using photopolymer storage media: Reflection holograms
(2000)
Hsieh, ML
;
Hsu, KY
;
Yeh, P
;
光電工程學系
;
Department of Photonics
We present a study of the grating detuning effect on the volume holographic data storage using photopolymer recording material. By using the Bragg matching condition, the angle shift and the decay of the diffraction efficiency of the reconstructed beam is obtained. Then the distortion of the readout page is described. And a method for pre-compensation of the incident angles of the reading beam is presented.
Effect of ruthenium doping on the optical and photorefractive properties of Bi12TiO20 single crystals
(2002-03-15)
Marinova, V
;
Hsieh, ML
;
Lin, SH
;
Hsu, KY
;
電子物理學系
Bi12TiO20 (BTO) single crystals nominally pure and doped with ruthenium are grown by top-seeded solution growth method. The effect of ruthenium concentration on optical and photorefractive properties is studied. Strong influence of doping on these properties is observed. It is shown that optical transmission of crystal samples with higher ruthenium content is shifted to the near IR spectral region, while the absorption coefficient is considerably increased. The optical activity of Ru doped crystals is further reduced in comparison with undoped BTO. Photochromic effect is observed in strongly doped crystal. Photorefractive properties are experimentally investigated using two-beam coupling. Response time and diffraction efficiency are changed with ruthenium content. (C) 2002 Elsevier Science B.V. All rights reserved.
Effect of the sensitizer on the properties of fully functionalized photorefractive epoxy polymers and their performance in the hologram image storage
(1999-06-01)
Chang, CJ
;
Whang, WT
;
Hsu, KY
;
Hsieh, ML
;
材料科學與工程學系
The 3-amino-9-ethyl carbazole (AEC)/Dispersed Orange 3 (DO3)/diglycidyl 1,2 cyclohexanedicarboxylate (DCD) main chain copolymers are synthesized and studied on their photorefractive (PR), photoconductive, and holographic characteristics. They are good hologram recording media because not only the stored hologram exhibits excellent fringe contrast with the resolution at about 20 mu m, but also the image can be stored, erased, and overwritten. The UV/Vis spectra shows that AEC segments may form charge transfer complexes with either DO3 segments or TNF sensitizers. By incorporating the sensitizer or increasing the charge transfer component concentration, the grating growth rate can be speeded up. Applying an electric field on the polymer film containing no sensitizer helps to elevate the grating growth speed, but it shows little influence on the grating growth speed of the films with sensitizers. More nonlinear optical (NLO) segments in the copolymer result in higher diffraction efficiency. The dark decay of the film depends on the dark conductivity. Incorporating sensitizers or more charge transport segments leads to more dark decay because of increasing dark conductivity. The dark decay of the PR properties at elevated temperature can also be evaluated by the thermal stimulated discharge current (TSDC) spectroscopy technique. (C) 1999 John Wiley & Sons, Inc.
Grating detuning effect on holographic memory in photopolymers
(2001-10-01)
Hsieh, ML
;
Hsu, KY
;
光電工程學系
;
Department of Photonics
We present a study of the grating detuning effect on the transmission and reflection holographic memories recorded in a photopolymer material. By using the Bragg matching condition, we analyze the angular shift and the degradation of the diffraction efficiency of the reconstructed Images. Based on these results, a method for precompensating the detuning effect has been proposed. (C) 2001 Society of Photo-Optical Instrumentation Engineers.
Modulation transfer function of a liquid crystal spatial light modulator
(1999-11-01)
Hsieh, ML
;
Hsu, KY
;
Paek, EG
;
Wilson, CL
;
光電工程學系
The modulation transfer function (MTF) of a pixelated liquid crystal spatial light modulator (LC-SLM) has been derived as a function of the fill factor. Based on the formula, we have investigated the dependence of the MTF on the orientations and spatial frequency of the input patterns. Furthermore, we have proposed and demonstrated a method for improving the MTF of a LC-SLM. (C) 1999 Published by Elsevier Science B.V. All rights reserved.
Optical and holographic properties of Bi4Ge3O12 crystals doped with ruthenium
(2003-10-01)
Marinova, V
;
Lin, SH
;
Hsu, KY
;
Hsieh, ML
;
Gospodinov, MM
Bi4Ge3O12 single crystals doped with different concentration of Ru were grown by the Czochralski technique. Optical absorption bands were induced by illumination with ultraviolet light at room temperature. The absorption coefficient values increased with increasing ruthenium concentration. The induced photochromic effect was completely reversible: all samples recovered their transparency after thermal treatment. Preliminary holographic recording experiments showed a fast response time and a relatively slow erase time during the reading process. (C) 2003 Kluwer Academic Publishers.
Optical image recognition using photorefractive crystal plates
(1997)
Hsieh, ML
;
Lin, SH
;
Hsu, KY
;
Hsieh, TC
;
Lin, SP
We demonstrate a real-time optical image recognition system using photorefractive thin plates. The effects of donor/acceptor concentration ratio in thin lithium niobate crystal plates on the photorefractive response time and the grating diffraction efficiency are presented.
Performance enhancement of a joint transform correlator using the directionality of a spatial light modulator
(1999-12-01)
Hsieh, ML
;
Paek, EG
;
Wilson, CL
;
Hsu, KY
;
光電工程學系
We observe that conventional electrically addressable spatial light modulators have different transfer functions along the fast (horizontal) and the slow (vertical) directions. We then propose to use the directionality of a spatial light modulator to increase the performance of a joint transform correlator. Our experimental results show that input space-bandwidth product of a joint transform correlator can be significantly increased by recording a hologram so that interference fringes run along the fast (horizontal) direction of a spatial light modulator. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)00412-2].
Photorefractive Fe : LiNbO3 crystal thin plates for optical information processing
(1999-07-01)
Lin, SH
;
Hsieh, ML
;
Hsu, KY
;
Hsieh, TC
;
Lin, SP
The effects of the donor acceptor concentration ratio in iron-doped Lithium niobate (Fe:LiNbO3) crystal plates on photorefractive response time and on grating diffraction efficiency are studied both theoretically and experimentally. The results provide a useful guide for designing photorefractive plates far optical information-processing applications. Two devices for real-time image recognition have been demonstrated: a photorefractive joint-transform correlator and a VanderLugt correlator. The former emphasizes fast response time, and the latter emphasizes high diffraction efficiency. By appropriate adjustment of the dopant concentration and the ratio of the donor acceptor levels, photorefractive Fe:LiNbO3 crystals that facilitate specific applications have been designed and fabricated. Shift-invariant image correlations have been achieved. (C) 1999 Optical Society of America [S0740-3224(99)01307-7].
Photorefractive properties and applications of Ru-doped Bi12TiO20 single crystals
(2001)
Marinova, V
;
Hsieh, ML
;
Lin, SH
;
Hsu, KY
;
光電工程學系
Bi12TiO20 single crystals doped with different concentrations of Ru were grown. Optical transmission spectra were measured. Photorefractive properties were experimentally investigated using two-beam coupling. Applications for optical information processing will be investigated.