| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical low pass filter which can accurately change a cut-off frequency into a desired value according to the change of image pickup conditions. SOLUTION: The incident plane of light transmitting members 31 and 32 formed by an optically isotropic photoelastic material is inclined obliquely to an optical axis. When a stress addition actuator 37 adds stress to the light transmitting members 31 and 32, the members 31 and 32 begin to function as a birefringent plate. Then, a detector 24 detects the birefringence properties of the members 31 and 32, and feeds back a detection result to control of the stress addition actuator 37. Accordingly, the cut-off frequency of the optical low pass filter can accurately be set. COPYRIGHT: (C)2003,JPO |
