| 摘要 |
PROBLEM TO BE SOLVED: To reduce the power consumption of a laser beam source, and to acquire an output independent of the output intensity of the laser beam source, in a sound pressure conversion device using the laser beam. SOLUTION: This device is equipped with a modulating signal oscillator 11 for oscillating a modulating signal, the laser beam source 13 whose beam output intensity is modulated corresponding to the modulating signal, a diaphragm 15 vibrating corresponding to a sound pressure, a photodetector 17 comprising a plurality of light receiving elements, a subtracter 23 for subtracting a plurality of signals S3, S4 outputted from the plural light receiving elements in the photodetector 17, an adder 25 for adding the plurality of signals S3, S4, and a divider 31 for dividing the output S5 from the subtracter 23 by a signal S8 corresponding to the output from the adder 25. The photodetector 17 receives a beam emitted from the laser beam source 13 and reflected by the diaphragm 15, and outputs a division result in the divider 31 as a signal corresponding to vibration of the diaphragm 15. COPYRIGHT: (C)2004,JPO
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