20 January 2003 Micromachined acoustic sensor array with diffraction-based optical interferometric detection
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Proceedings Volume 4985, MOEMS Display and Imaging Systems; (2003) https://doi.org/10.1117/12.472862
Event: Micromachining and Microfabrication, 2003, San Jose, CA, United States
A diffraction-based interferometric optical detection method for micromachined acoustic sensors can provide better sensitivity as compared to conventional capacitance detection schemes especially at low frequency range. The optical detection method, complete with optoelectronics readout, can be integrated with a capacitive micromachined acoustic transducer. The method is utilized on a 19×19 capacitive micromachined ultrasonic transducer (cMUT) array to demonstrate ultrasonic imaging of wire targets at 750kHz in air. A silicon photodiode (PD) array is also designed and fabricated in a standard 1.3μm CMOS technology, and through-wafer etching of holes for optical interconnect is performed on the same silicon platform. Further improvement of displacement sensitivity in a resonant-cavity-enhanced (RCE) acoustic sensor is theoretically analyzed including the loss effect in the mirror, and the theoretical results are experimentally verified by measurements on devices with a thin metallic bottom mirror made of silver.
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Wook Lee, Wook Lee, Neal Hall, Neal Hall, F. Levent Degertekin, F. Levent Degertekin, } "Micromachined acoustic sensor array with diffraction-based optical interferometric detection", Proc. SPIE 4985, MOEMS Display and Imaging Systems, (20 January 2003); doi: 10.1117/12.472862; https://doi.org/10.1117/12.472862

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