| 摘要 |
PROBLEM TO BE SOLVED: To hardly cause a false signal even by mounting deviation of a diffraction grating type optical low pass filter by setting the period of a solid-state image pickup element in the pixel arrangement direction specified times of the pixel period of the solid image pickup element. SOLUTION: This solid image pickup element 12 is a CCD(charge coupled device) consisting of many pixels 12a arranged in a fixed pixel periodΛCCD. The optical low-pass filter 13 is mounted so that the direction of a diffraction grating pattern becomes parallel to the pixel arrangement direction of the solid image pickup element 12. At this time, the optical low-pass filter is provided with the diffraction grating pattern of a since wave shape pattern, and the periodΛMLA of the diffraction grating pattern becomes close to 3.0 times of the pixel periodΛCCD of the solid image pickup element 12, that is, becomesΛMLA≈3.0ΛCCD. Thus, the pattern periodΛMLA of the optical low-pass filter 13 becomes a very small value of the pixel periodΛCCD extent, and a visible shadow is never caused on the solid-state image pickup element 12 by the optical low pass filter 13.
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