| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a subminiature acoustoelectric transducer that causes less surrounding noise by improving the sensitivity only in a prescribed axial direction. SOLUTION: The acoustoelectric transducer is provided with a board on which vertical cavity surface light emitting laser beam elements whose luminous emission strength distribution is almost concentrically uniform are arranged and light receiving elements to receive the emitted light from the beam emitting elements are placed, a diaphragm that is placed nearly parallel and closely to a position opposed to the board, vibrated by sound pressure, reflects the light from the beam emitting elements to the light receiving elements, a light source drive circuit that supplies a drive current to the beam emitting elements, and a negative feedback circuit that supplies part of the signal outputted from the light receiving elements to the light source drive circuit as a negative feedback signal.</p> |
