| 摘要 |
A small photodetector type microphone ( 10 ) exhibiting excellent directivity without requiring any mirror surface. A diaphragm ( 27 ) vibrates in response to a sound pressure. An optical waveguide ( 28 ) is formed along the diameter of the diaphragm ( 27 ) and integral vibration of the optical waveguide ( 28 ) and the diaphragm ( 27 ) causes a variation in the quantity of light leaking from the optical waveguide ( 28 ) to the outside thus causing a variation in the quantity of light being transmitted across the optical waveguide ( 28 ). The optical waveguide ( 28 ) has one end side for introducing light into a light emitting elements ( 20 ) and the other end side for delivering light to a light receiving element ( 24 ). The light receiving element ( 24 ) outputs an electric signal related to the quantity of incident light.
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