Browsing by Author "Hsu, Fan-Hsi"

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Heterodyne moire surface profilometry
(2014-02-10)
Chang, Wei-Yao
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Hsu, Fan-Hsi
;
Chen, Kun-Huang
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Chen, Jing-Heng
;
Hsu, Ken Y.
In this study, a novel moire fringe analysis technique is proposed for measuring the surface profile of an object. After applying a relative displacement between two gratings at a constant velocity, every pixel of CMOS camera can capture a heterodyne moire signal. The precise phase distribution of the moire fringes can be extracted using a one-dimensional fast Fourier transform (FFT) analysis on every pixel, simultaneously filtering the harmonic noise of the moire fringes. Finally, the surface profile of the tested objected can be generated by substituting the phase distribution into the relevant equation. The findings demonstrate the feasibility of this measuring method, and the measurement error was approximately 4.3 mu m. The proposed method exhibits the merits of the Talbot effect, projection moire method, FFT analysis, and heterodyne interferometry. (C) 2014 Optical Society of America
Optimized design of multiport optical circulator
(2014)
Hsu, Fan-Hsi
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Chen, Jing-Heng
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Chen, Kun-Huang
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Yeh, Chien-Hung
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Hsu, Ken Y.
This research proposes a practical multiport optical circulator design by using polarizing beam splitter cubes as spatial walk-off polarizers. The use of Porro prisms for directing light requires fewer components and improves space-efficiency. Therefore, a high performance device can be produced at a reduced cost. A six-port optical circulator prototype was fabricated to show the feasibility of the proposed design. The insertion losses range between 0.52 and 1.05 dB, the isolations range between 26.20 and 45.13 dB, and the return losses are 27.72 dB. The benefits of this design\'s simple and symmetrical structure include costefficiency, simple fabrication processes, polarization-independence, the resolve of polarization-mode dispersion issues, and high performance. Additionally, the number of ports can be increased easily. (c) 2014 Elsevier GmbH. All rights reserved.
Prism-hologram-prism sandwiched recording method for polarization-selective substrate-mode volume holograms with a large diffraction angle
(2018-08-06)
Hsu, Fan-Hsi
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Han, Chien-Yuan
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Chen, Kun-Huang
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Hsu, Ken-Yuh
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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
Reconstruction of surface profile by using heterodyne moire method
(2012-11-01)
Chang, Wei-Yao
;
Hsu, Fan-Hsi
;
Chen, Kun-Huang
;
Chen, Jing-Heng
;
Hsieh, Hung-Chih
Based on the projection moire method and heterodyne interferometry, this study proposes an alternative method for reconstructing the surface profile of an object. Obliquely illuminating a linear grating with an expanding collimated light, a self-image of this grating can be generated and projected on the surface of the tested object. The grating fringes distorted by the surface profile are imaged on the reference grating to form the moire fringes. These moire fringes are then captured by a CMOS camera. If the projection grating moves with a constant velocity along the grating plane, each pixel of the CMOS camera records a series of sampling points of the sinusoidal wave. These sinusoidal waves behave like heterodyne interferometric signals. Hence, the accurate and stable phase distribution of the tested object surface can be obtained using the IEEE 1241 least-squares sine fitting algorithm and 20 phase unwrapping. Substituting the phase values into the derived equation, the surface profile of the tested object can be reconstructed. The experiments in this study verified the feasibility of this method, showing a measurement resolution of approximately 1.9 mu m. The proposed measurement method has the merits of both the projection moire method and the heterodyne interferometry. (C) 2012 Elsevier B.V. All rights reserved.