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Journal of Biomedical Optics • Open Access

Three-dimensional vibrometry of the human eardrum with stroboscopic lensless digital holography
Author(s): Morteza Khaleghi; Cosme Furlong; Mike Ravicz; Jeffrey T. Cheng; John Rosowski

Paper Abstract

The eardrum or tympanic membrane (TM) transforms acoustic energy at the ear canal into mechanical motions of the ossicles. The acousto-mechanical transformer behavior of the TM is determined by its shape, three-dimensional (3-D) motion, and mechanical properties. We have developed an optoelectronic holographic system to measure the shape and 3-D sound-induced displacements of the TM. The shape of the TM is measured with dual-wavelength holographic contouring using a tunable near IR laser source with a central wavelength of 780 nm. 3-D components of sound-induced displacements of the TM are measured with the method of multiple sensitivity vectors using stroboscopic holographic interferometry. To accurately obtain sensitivity vectors, a new technique is developed and used in which the sensitivity vectors are obtained from the images of a specular sphere that is being illuminated from different directions. Shape and 3-D acoustically induced displacement components of cadaveric human TMs at several excitation frequencies are measured at more than one million points on its surface. A numerical rotation matrix is used to rotate the original Euclidean coordinate of the measuring system in order to obtain in-plane and out-of-plane motion components. Results show that in-plane components of motion are much smaller (<20%) than the out-of-plane motions’ components.

Paper Details

Date Published: 4 February 2015
PDF: 11 pages
J. Biomed. Opt. 20(5) 051028 doi: 10.1117/1.JBO.20.5.051028
Published in: Journal of Biomedical Optics Volume 20, Issue 5
Show Author Affiliations
Morteza Khaleghi, Worcester Polytechnic Institute (United States)
Cosme Furlong, Worcester Polytechnic Institute (United States)
Massachusetts Eye and Ear Infirmary (United States)
Harvard Medical School (United States)
Mike Ravicz, Massachusetts Eye and Ear Infirmary (United States)
Harvard Medical School (United States)
Jeffrey T. Cheng, Massachusetts Eye and Ear Infirmary (United States)
Harvard Medical School (United States)
John Rosowski, Massachusetts General Hospital (United States)
Harvard Medical School (United States)

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