Patent ID: 8306429
Filing Date: 2012-11-06
Classification: G01H

Abstract:
1. An optical ultrasonic microphone, which is a microphone for receiving a sound wave from an ambient space filled with a gas, the optical ultrasonic microphone comprising: a base that is provided with (i) an opening through which the sound wave is received from the ambient space and (ii) an acoustic waveguide for transmitting the sound wave received by the opening; a light source for applying light; an optical acoustic propagation medium portion held by the base, the optical acoustic propagation medium forming at least one portion of the acoustic waveguide through which the sound wave from the acoustic waveguide and the light from the light source are propagated; a light detecting means for detecting the light emitted from the optical acoustic propagation medium portion and for detecting a modulation of the light caused by the sound wave; and an operation unit for finding a sound pressure from results of the detection by the light detecting means, wherein, between a density ρ and wherein the operation unit finds the sound pressure from the result of the detection by the light detecting means according to the following expression: where P is the sound pressure, ρ