| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical microphone system where the sensitivity in a prescribed axial direction only is enhanced so as not to be affected by the surrounding noises. SOLUTION: The optical microphone system that is provided with a diaphragm 2 vibrated by a sound pressure, a light source 3 emitting a light beam to the diaphragm 2, a photo detector 5 that receives a reflected light of the light beam emitted to the diaphragm 2 and outputs a signal corresponding to the vibration of the diaphragm 2, and a light source drive circuit 13 that drives the light source 3 by supplying a prescribed current to the light source 3, is provided with a negative feedback circuit 100 that supplies part of a signal outputted from the photo detector 5 to the light source drive circuit 13 as a negative feedback signal.
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