| 摘要 |
PROBLEM TO BE SOLVED: To arbitrarily control the interception frequencies of a central part and peripheral part in accordance with a frequency characteristic of an optical element or the like in order to prevent degradation in the image quality of an image made incident on the optical element or the like. SOLUTION: The optical low pass filter includes: a substrate 21 disposed such that a first face 21a crosses the direction of the optical axis of incident light; and a diffraction grating group 22 having diffraction gratings formed on the first face 21a so as to project in the direction of the optical axis of the incident light, and adopted to intercept the spatial frequency of the incident light. The diffraction grating group 22 comprises: the first refraction grating with a line width L1, frequency P, and thickness d; and the second diffraction grating with a line width L2, the frequency P, and the thickness d. COPYRIGHT: (C)2006,JPO&NCIPI
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