| 摘要 |
There is provided an optical low pass filter passing only a lower spatial frequency using a phase grating and the structure of the grating. The optical low pass filter utilizes the two-dimensionally arranged phase grating for the purpose of removing an image with a higher spatial frequency in an imaging system employing a semiconductor solid-state imaging device such as CCD image sensor or CMOS image sensor, The optical low pass filter which suppresses a spatial frequency component higher than a specific frequency and passes a component lower than the specific frequency in an imaging system sensing input images includes a grating generating the phase shift of 0, a grating generating the phase shift of phi, arranged at the right and bottom of the 0-phase shift grating, and a grating generating the phase shift of 2phi, arranged at the diagonal side of the 0-phase shift grating.
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