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Optical Engineering • Open Access

Digital holographic measurements of shape and three-dimensional sound-induced displacements of tympanic membrane
Author(s): Morteza Khaleghi; Weina Lu; Ivo Dobrev; Jeffrey Tao Cheng; Cosme Furlong; John Rosowski

Paper Abstract

Acoustically induced vibrations of the tympanic membrane (TM) play a primary role in the hearing process, in that these motions are the initial mechanical response of the ear to airborne sound. Characterization of the shape and three-dimensional (3-D) displacement patterns of the TM is a crucial step to a better understanding of the complicated mechanics of sound reception by the ear. Sound-induced 3-D displacements of the TM are estimated from shape and one-dimensional displacements measured in cadaveric chinchillas using a lensless dual-wavelength digital holography system (DWDHS). The DWDHS consists of laser delivery, optical head, and computing platform subsystems. Shape measurements are performed in double-exposure mode with the use of two wavelengths of a tunable laser, while nanometer-scale displacements are measured along a single sensitivity direction with a constant wavelength. Taking into consideration the geometrical and dimensional constrains imposed by the anatomy of the TM, we combine principles of thin-shell theory together with displacement measurements along a single sensitivity vector and TM surface shape to extract the three principal components of displacement in the full-field-of-view. We test, validate, and identify limitations of this approach via the application of finite element method to artificial geometries.

Paper Details

Date Published: 17 July 2013
PDF: 12 pages
Opt. Eng. 52(10) 101916 doi: 10.1117/1.OE.52.10.101916
Published in: Optical Engineering Volume 52, Issue 10
Show Author Affiliations
Morteza Khaleghi, Worcester Polytechnic Institute (United States)
Weina Lu, Worcester Polytechnic Institute (United States)
Ivo Dobrev, Worcester Polytechnic Institute (United States)
Jeffrey Tao Cheng, Massachusetts Eye and Ear Infirmary (United States)
Cosme Furlong, Worcester Polytechnic Institute (United States)
John Rosowski, Harvard Medical School (United States)

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