Advanced Optical Microphone

Bakhoum, Ezzat G.; Cheng, Hung-Ming

doi:10.1109/jsen.2013.2281727

Cited by 4 publications

(2 citation statements)

References 21 publications

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“…The optical vibrometers can accurately measure sub-wavelength mechanical vibrations without contacting objects. These characteristics allow the technology to have broad application prospects in various fields, such as optical microphone [ 1 , 2 , 3 ], surveillance of audio signal in rescue [ 4 , 5 , 6 ], visual accelerometer [ 7 ], and so on.…”

Section: Introductionmentioning

confidence: 99%

The 20k Samples-Per-Second Real Time Detection of Acoustic Vibration Based on Displacement Estimation of One-Dimensional Laser Speckle Images

Haruyama

2021

Sensors

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Audio signal acquisition using a laser speckle image is an appealing topic since it provides an accurate and non-contact solution for vibration measurement. However, due to the limitation of camera frame rate and image processing speed, previous research could not achieve real time reconstruction of an audio signal. In this manuscript, we use a one-dimensional laser speckle image to measure the acoustic vibration of sound source and propose a fast and sub-pixel accuracy algorithm to estimate the displacement of captured one-dimensional laser speckle images. Compared with previous research, the proposed method is faster and more accurate in displacement estimation. Owing to this, the frequency bandwidth and the robustness are significantly increased. Experiment results show that the proposed system can achieve 20k samples-per-second sampling rate, and the audio signal can be reconstructed with high quality in real time.

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Section: Introductionmentioning

confidence: 99%

The 20k Samples-Per-Second Real Time Detection of Acoustic Vibration Based on Displacement Estimation of One-Dimensional Laser Speckle Images

Haruyama

2021

Sensors

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“…29 In a review article, Bilaniuk summarized various sensing techniques for optical microphone applications. 30 Several different readout techniques have been used to realize optical-based microphones using fiber optics, 31,32 a combination of laser-emitting diodes (LED) and a charge-coupled device (CCD), 33 and optical-lever approaches. 34 A microphone that uses interference through a diffraction grating has also been introduced in prior work.…”

Section: Introduction and A Review Of Noise Sources In Miniature Mmentioning

confidence: 99%

Towards a sub 15-dBA optical micromachined microphone

Kim

Hall

2014

The Journal of the Acoustical Society of America

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Micromachined microphones with grating-based optical-interferometric readout have been demonstrated previously. These microphones are similar in construction to bottom-inlet capacitive microelectromechanical-system (MEMS) microphones, with the exception that optoelectronic emitters and detectors are placed inside the microphone's front or back cavity. A potential advantage of optical microphones in designing for low noise level is the use of highly-perforated microphone backplates to enable low-damping and low thermal-mechanical noise levels. This work presents an experimental study of a microphone diaphragm and backplate designed for optical readout and low thermal-mechanical noise. The backplate is 1 mm Â 1 mm and is fabricated in a 2-lm-thick epitaxial silicon layer of a silicon-on-insulator wafer and contains a diffraction grating with 4-lm pitch etched at the center. The presented system has a measured thermal-mechanical noise level equal to 22.6 dBA. Through measurement of the electrostatic frequency response and measured noise spectra, a device model for the microphone system is verified. The model is in-turn used to identify design paths towards MEMS microphones with sub 15-dBA noise floors.

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