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Proceedings Paper

Laser interferometry for ear ossicular motion detection
Author(s): Joseph J. Suter; Jay C. Poret; Doug E. Mattox
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Paper Abstract

The emphasis of this project has been to initially detect the displacements of the eardrum by using a laser interferometer. A small cobalt-samarium magnet (typically weighing less than 4 mg) was placed on human cadaver eardrums and positioned inside a solenoid coil. An ac modulated signal, having a frequency range of 500 - 2500 Hz, was passed through the coil. This signal created an ac magnetic field inside the coil that caused the magnet to vibrate at the modulation frequency. A commercial (TSI) laser interferometer as well as a laboratory-based fiber-optic interferometer, both operating at 632 nm, were used to examine the displacements initially. For measurements made with the fiber-optic interferometer at a frequency of 1500 Hz, the displacement of the eardrum was approximately 68 nm. The response decreased linearly at a rate of 0.02 nm/Hz for frequencies greater than 1500 Hz. This paper reports on the experimental apparatus as well as the experimental results. Details on the design of the driving circuit and the interferometers also are presented.

Paper Details

Date Published: 28 July 1994
PDF: 6 pages
Proc. SPIE 2131, Biomedical Fiber Optic Instrumentation, (28 July 1994); doi: 10.1117/12.180751
Show Author Affiliations
Joseph J. Suter, Johns Hopkins Univ. (United States)
Jay C. Poret, Johns Hopkins Univ. (United States)
Doug E. Mattox, Univ. of Maryland School of Medicine (United States)


Published in SPIE Proceedings Vol. 2131:
Biomedical Fiber Optic Instrumentation
James A. Harrington; David M. Harris; Abraham Katzir; Fred P. Milanovich, Editor(s)

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