| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical low-pass filter capable of easily changing filter characteristics. SOLUTION: The optical filter 4 has a light transmitting member 41 on which object light ray is made incident and a piezoelectric body 42. When a high-frequency voltage of 1 MHz to 10 MHz is applied to the piezoelectric body 42 which is provided on a side A of the light transmitting member 41 by a driving circuit 8 and the light transmitting member 41 is vibrated, a compressional wave (an ultrasonic wave) is generated inside the member 41. Then, a refraction factor distribution which periodically changes from the side A to a side C is formed in the inside of the member 41 by the generation of the compressional wave and the object light ray is separated into a plurality of light rays by diffraction by sound effect. Thus, the filter characteristic of the member 41 can be changed by changing the magnitude of power to be supplied to the piezoelectric body 42. COPYRIGHT: (C)2006,JPO&NCIPI
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