| 摘要 |
PROBLEM TO BE SOLVED: To make it unnecessary to perform the correction of a focal position because of switching a filter without causing the upsizing of a filter device. SOLUTION: The filter device 3 is constituted by providing a plurality of filter housing parts 32 on a rotary type filter disk 31. A filter 41 having a predetermined refractive index and thickness is housed in a filter housing part 32A, an infrared light transmitting filter 42 transmitting only the light in a predetermined wavelength region is housed in a filter housing part 32B, and an ND filter 43 is housed in a filter housing part 32C out of the filter housing parts. The filters are respectively made to abut on abutting parts 37A and 37B having different depth, whereby the surfaces of the respective filters are nearly aligned with each other, and then they are attachably/detachably fixed by a fixing member 33. COPYRIGHT: (C)2007,JPO&INPIT
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