| 摘要 |
PURPOSE:To obtain high sensitivity and a wide dynamic range through simple constitution by allowing laser light reflected by a diaphragm and reference laser light to strike a photodetector, and thus obtaining an interference signal. CONSTITUTION:Light from a laser 1 is split into two through a halfmirror 2; one light is reflected by a fixed mirror 4, and the other light is reflected by a diaphragm 3. Then, they are caused to illuminate a photodetector 5. When the diaphragm 3 is diaplaced by an acoustic wave, the optical path length from the mirror 2 to the photodetector 5 varies to cause interference phenomenon of the light with the reference light from the mirror 4 on the photodetector 5. This is transduced into an electric signal to obtain an electric audio signal from displacement information on the diaphragm 3. |
