Browsing by Author "Chang, Hsuan T."

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Integral computer-generated hologram via a modified Gerchberg-Saxton algorithm
(2015-01-01)
Wu, Pei-Jung
;
Chen, Chien-Yue
;
Deng, Qing-Long
;
Chang, Hsuan T.
;
Lin, Bor-Shyh
An integral computer-generated hologram, which modulates the phase function of an object based on a modified Gerchberg-Saxton algorithm and compiles a digital cryptographic diagram with phase synthesis, is proposed in this study. When the diagram completes position demultiplexing decipherment, multi-angle elemental images can be reconstructed. Furthermore, an integral CGH with a depth of 225 mm and a visual angle of +/- 11 degrees is projected through the lens array.
MGSA-Type Computer-Generated Holography for Vision Training With Head-Mounted Display
(2014-06-01)
Deng, Qing-Long
;
Lin, Bor-Shyh
;
Chang, Hsuan T.
;
Huang, Guan-Syun
;
Chen, Chien-Yue
A computer-generated holography head-mounted display (HMD) for vision training is proposed in this study. Based on modified Gerchberg-Saxton algorithm (MGSA) to calculate the phase distribution of light wave and the position multiplexing, the images with fixation disparity or changed disparity are successfully coded as phase only function. After decryption and reconstruction, the left and the right images are transmitted to HMD for a trainee viewing the images with disparity changes and moderating the stereoacuity of both eyes, ranging from 32.24 arcsec to 2.14 arcmin. The images reconstructed with MGSA-type CGH present the relative diffraction efficiency about 86% and visibility 94%, which not only provide high-contrast image quality, and the changing disparity allows achieving the training effect.
Speckle reduction by combination of digital filter and optical suppression in a modified Gerchberg-Saxton algorithm computer-generated hologram
(2014-09-20)
Chen, Chien-Yue
;
Deng, Qing-Long
;
Wu, Pei-Jung
;
Lin, Bor-Shyh
;
Chang, Hsuan T.
A speckleless illuminated modified-Gerchberg-Saxton-algorithm-type computer-generated hologram, which adopts a lower frequency of the iterative algorithm and calculation time, is proposed to code a hologram with two signals and position a multiplexing phase-only function, which can reconstruct the left and the right viewing holograms on the pupillary-distance position after the decryption and still maintain the content with high contrast and definition. The reconstructed image quality presents root mean square error of 0.03, with a diffraction efficiency of 87%, and signal-to-noise ratio of 8 dB after the analysis. Furthermore, two denoising techniques for the digital filter and optical suppression are combined, in which the speckle suppression with pseudorandom phase modulation and a rotating diffuser are utilized for successfully reducing the speckle contrast, which was reduced to below 4%. The goal was to reduce visual fatigue for the viewers. (C) 2014 Optical Society of America