| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical microphone having flat frequency characteristics up to a high-frequency region. SOLUTION: The optical microphone includes a prism 2, a metal layer 3, a sound reception layer 4, a light source 5, a light receiver 6, a light source driving circuit 8, and a detection circuit 9. Porous materials such as silica drying gel are used for the sound reception layer to detect a change in refractive index of the sound reception layer, which is caused by a sound pressure, using a change in surface plasmon resonance absorption. Thereby, a microphone having flat frequency characteristics to a high-frequency region can be provided, without causing reduction in sensitivity due to reduction in size. COPYRIGHT: (C)2011,JPO&INPIT
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