82 H. Tang et al. Fig. 10.5 Color-coded images represent the shape of TM: (a) 3D mesh plot of raw data of normal TM; (b) raw data of normal TM in 2D; (c) high-order polynomial fitting of (b). (d) Histogram of residuals of the high-order polynomial fitting of normal TM; (e) raw data of TM when the middle ear cavity is injected with fluid. (f) High-order polynomial fitting of (e). (g) Histogram plot of residuals of the high-order polynomial fitting of fluid injection 10.4 Conclusion This study demonstrates a new shape measurement method for the TM based on multiple angle digital holography using a single wavelength laser source and temporal phase unwrapping algorithm. With this method, it is possible to compute the complete surface topology map of the natural tympanic membrane without the need for the spatial unwrapping of phase difference maps. The method was validated by measuring a stepwise gauge provided by NIST with known dimensions. A fresh non-fixed human postmortem tympanic membrane was measured with and without middle ear fluid injection. The results show the proposed method is sensitive to the shape change induced by fluid injection, suggesting a potential for in vivo measurements and diagnosis of middle ear diseases. Acknowledgments This work has been funded (R01DC016079) by the National Institute on Deafness and Other Communication Disorders (NIDCD), the National Institute of Health (NIH), and the Massachusetts Eye and Ear Infirmary (MEEI). The authors also gratefully acknowledge the support of the Mechanical Engineering Department, Worcester Polytechnic Institute, and contributions by graduate and undergraduate students of the CHSLT and MEEI. References 1. Rosowski, J.J.: Outer and Middle Ears Comparative Hearing: Mammals, pp. 172–247. Springer, New York (1994) 2. Geisler, C.D.: From Sound to Synapse: Physiology of the Mammalian Ear. Oxford University Press, Oxford/New York (1998) 3. Wang, X., Guan, X., Pineda, M., Gan, R.Z.: Motion of tympanic membrane in guinea pig otitis media model measured by scanning laser Doppler vibrometry. Hear. Res. 339, 184–194 (2016) 4. Razavi, P., Tang, H., Rosowski, J.J., Furlong, C., Cheng, J.T.: Combined high-speed holographic shape and full-field displacement measurements of tympanic membrane. J. Biomed. Opt. 24(3), 031008 (2018) 5. Tang, H., Razavi, P., Pooladvand, K., Psota, P., Maftoon, N., Rosowski, J.J., Furlong, C., Cheng, J.T.: High-speed holographic shape and fullfield displacement measurements of the tympanic membrane in normal and experimentally simulated pathological ears. Appl. Sci. 9(14), 2809 (2019) 6. Ichirou, Y., Ohta, S., Kato, J.: Surface contouring by phase-shifting digital holography. Opt. Lasers Eng. 36(5), 417–428 (2001) 7. Psota, P., Tang, H., Pooladvand, K., Vít, L., Furlong, C., Rosowski, J.J., Cheng, J.T.: Investigation of tympanic membrane shape using digital holography. Optics Measur. Int. Conf. 11385, 113850G (2019)
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