Khaleghi, MortezaFurlong, CosmeRavicz, MikeCheng, JeffreyRosowski, John2016-03-012015Khaleghi, Morteza, Cosme Furlong, Mike Ravicz, Jeffrey Tao Cheng, and John J. Rosowski. 2015. “Three-dimensional vibrometry of the human eardrum with stroboscopic lensless digital holography.” Journal of Biomedical Optics 20 (5): 051028. doi:10.1117/1.JBO.20.5.051028. http://dx.doi.org/10.1117/1.JBO.20.5.051028.1083-3668http://nrs.harvard.edu/urn-3:HUL.InstRepos:25658391Abstract. 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.en-USPaper3-D displacement measurementsdigital holographyholographic contouringstroboscopic measurementstympanic membraneJournal Article2016-03-0110.1117/1.JBO.20.5.051028