M.Sc Thesis

M.Sc StudentGrechin Sveta
SubjectImaging Acoustic Vibrations in an Ear Model Using Spectrally
Encoded Interferometry
DepartmentDepartment of Biomedical Engineering
Supervisor ASSOCIATE PROF. Dvir Yelin
Full Thesis textFull thesis text - English Version


Imaging vibrational patterns of the tympanic membrane could provide an accurate measurement of its mechanical properties and allow an early diagnosis of various hearing disorders. Several optical technologies have been employed to address this challenge using point scanning and full field interferometric measurements. These approaches, however, suffer from either slow scanning speed or low imaging rate that limit their potential for clinical applications. Spectrally encoded imaging has been previously demonstrated capable of imaging tissue acoustic vibrations with high spatial resolution, including full two-dimensional mapping of both amplitude and phase.

In this work, we demonstrate an experimental optical apparatus that could be incorporated into a commercially available digital otoscope as a compact add-on. By analyzing the spectral interferograms with custom-built processing software, we demonstrate high-resolution vibration imaging of a tympanic membrane within an ear model. During the experiments the membrane was excited by sound waves transmitted through one of the input ports of the otoscope. The system could measure full membrane vibration patterns across a 4.5-mm-diameter field of view at frequencies that span the human auditory range, with an axial resolution of only a few nanometers.

Our work is a step toward improving the capability of physicians to achieve faster and more accurate hearing diagnostics. Further work is needed for building a portable system for a fast and reliable scanning and in vivo experiments.