| 摘要 |
An optical low pass filter includes: a light transmitting member (41); and a refractive index distribution generation means (42) that generates a refractive index distribution cyclically changing within the plane of the light transmitting member (41). The refractive index distribution generation means includes a piezoelectric element, for example, and generates the refractive index distribution by generating the compressional wave in the light transmitting member (41) with a high frequency voltage being applied to the piezoelectric element.
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