| 摘要 |
PROBLEM TO BE SOLVED: To provide a photoelectric detector that can be further miniaturized without deteriorating the optical S/N ratio. SOLUTION: In the photoelectric detector for detecting particles, a light- emitting device 4 and a photodetector 5 being arranged in an optical chamber 2 so that the light axes cross each other are provided and scattered light of light from the light-emitting device 4 due to such particles as smoke and dust at a detection region that is a region where the light projection region of the light-emitting device 4 and the light reception region of the photodetector 5 overlap each other is received by the photodetector 5. In the photoelectric detector, a condensing means G and a light trap T are provided at a position opposite to the light-emitting device 4, thus light from the light-emitting device 4 at the opening T1 of the light trap T is made to condese by the condensing means G.
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