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Proceedings Paper

Feasibility of guided-wave optical microphone based on elasto-optic effect
Author(s): Hiroyuki Nikkuni; Masashi Ohkawa; Seishi Sekine; Takashi Sato
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Paper Abstract

In this paper, the feasibility of a glass-based guided-wave optical microphone is described. The optical microphone consists of a rectangular diaphragm and a straight waveguide on the diaphragm. The sensitivity of the microphone and the resonance frequency of the diaphragm are dependent on the diaphragm dimensions. In this study, to confirm operation of the proposed optical microphone, the target values for phase sensitivity and resonance frequency were set at 1.3 mrad/Pa and 5 kHz, respectively. By design considerations, the diaphragm dimensions were determined to be 16 mm × 16 mm × 0.15 mm. After fabrication, a sound wave of 1 kHz and 25 Pa, corresponding to 122 dB-SPL (sound pressure level), was applied to the microphone. In the experiment, the intensity-modulated output with the same frequency as the applied sound wave was obtained, but the observed output was unexpectedly caused by misalignment of the optical components due to mechanical vibration. The estimated output signal by the normal operation of the microphone for a sound pressure of 25 Pa was 1/10 - 1/100 of the noise level, according to the measured output characteristic to static pressure. In order to detect normal speech ranging from 55 to 65 dB-SPL, the S/N ratio should be improved by a factor of more than 104.

Paper Details

Date Published: 6 December 2005
PDF: 8 pages
Proc. SPIE 6049, Optomechatronic Sensors and Instrumentation, 604907 (6 December 2005); doi: 10.1117/12.649176
Show Author Affiliations
Hiroyuki Nikkuni, Niigata Univ. (Japan)
Masashi Ohkawa, Niigata Univ. (Japan)
Seishi Sekine, Niigata Univ. (Japan)
Takashi Sato, Niigata Univ. (Japan)

Published in SPIE Proceedings Vol. 6049:
Optomechatronic Sensors and Instrumentation
Yasuhiro Takaya, Editor(s)

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