Making optical low-pass spatial filters by thin-film phase grating |
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Authors: | Sheng-Hui Chen Yong-Tong Zou Cheng-chung Lee |
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Affiliation: | 1. Institute of Optical Science and Thin Film Technology Center , National Central University , Chung-Li, Taiwan ericchen@ios.ncu.edu.tw;3. Institute of Optical Science and Thin Film Technology Center , National Central University , Chung-Li, Taiwan |
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Abstract: | A modified rule was applied to design a grating optical low-pass spatial filter (GOLF) with a thin-film phase grating. This filter differed from the crystal type of optical low-pass spatial filter (OLPF). The fabrication method of the thin-film phase GOLF was also different from the conventional lithographic process. A new fabrication method utilizing a metal mesh mask and a thin-film coating process was applied to make the GOLF. The process had the advantages of being simple and cheap, and would thus be good for mass-production. The modulation transfer function (MTF) of the device was measured and the results agree well with the theoretical calculations. Finally, the GOLF was installed on a digital camera which was used to capture images of the circular zone plane (CZP), to show the Moiré pattern suppression ability. |
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