OPTICAL LOW-PASS FILTER

Japanese Patent JPH04204914

A

PURPOSE:To improve a low-pass effect by specifying the angle formed of the grating arrangement directions of two diffraction gratings of a phase type to a specific range. CONSTITUTION:The optical LPF 3 is disposed with the diffraction grating 31 of the phase type having the grating arrangement in the direction approximately perpendicular to the horizontal scanning direction of an image pickup means 2 and the diffraction grating 32 having the grating arrangement rotated around an optical axis 4 by an angle theta of 45 deg.