| 摘要 |
PROBLEM TO BE SOLVED: To receive infrared light having a wavelength corresponding to band-pass characteristics of a band-pass filter over a wide angle range by removing noise light which is incident from an oblique direction. SOLUTION: A photodetector module 10 includes the band-pass filter 15 formed of a light-transmissive member 16 in a shape formed by cutting a portion of a hollow sphere in a bowl shape, and a photodetector 14 is disposed so that the center of a photodetection surface 14a of the photodetector 14 is positioned in the center of the hollow sphere associated with the base shape of the band-pass filter 15. The band-pass filter 15 has a spherical surface, so the band-pass filter 15 can exhibit its original band-pass performance at any place for light made incident along a normal direction to transmit light having a wavelength included in a transmission wavelength band while securely blocking noise light from the oblique direction, so that the photodetector module 10 is hardly affected by the noise light and has stable photodetection characteristics irrelevantly to the incident direction. COPYRIGHT: (C)2009,JPO&INPIT
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