Simultaneous full-field 3-D vibrometry of the human eardrum using spatial-bandwidth multiplexed holography

Abstract

Abstract. Holographic interferometric methods typically require the use of three sensitivity vectors in order to obtain three-dimensional (3-D) information. Methods based on multiple directions of illumination have limited applications when studying biological tissues that have temporally varying responses such as the tympanic membrane (TM). Therefore, to measure 3-D displacements in such applications, the measurements along all the sensitivity vectors have to be done simultaneously. We propose a multiple-illumination directions approach to measure 3-D displacements from a single-shot hologram that contains displacement information from three sensitivity vectors. The hologram of an object of interest is simultaneously recorded with three incoherently superimposed pairs of reference and object beams. The incident off-axis angles of the reference beams are adjusted such that the frequency components of the multiplexed hologram are completely separate. Because of the differences in the directions and wavelengths of the reference beams, the positions of each reconstructed image corresponding to each sensitivity vector are different. We implemented a registration algorithm to accurately translate individual components of the hologram into a single global coordinate system to calculate 3-D displacements. The results include magnitudes and phases of 3-D sound-induced motions of a human cadaveric TM at several excitation frequencies showing modal and traveling wave motions on its surface.

Attenuating the ear canal feedback pressure of a laser-driven hearing aid

“…5(b), at 0.7 kHz, all the points on the surface of the TM vibrate almost in phase in the case of the 1D force, whereas in the corresponding 3D case there is almost a 180 phase difference between the anterior and posterior halves of the TM, which causes the feedback pressure on the two sides to essentially cancel out and therefore significantly reduce the overall EC feedback pressure. As the excitation frequency increases, the complexity of the vibrational patterns of the TM continues to increase (Tonndorf and Khanna, 1972;Rosowski et al, 2009;Khaleghi et al, 2015). For instance, as shown in Fig.…”

High-Speed Holographic Shape and Full-Field Displacement Measurements of the Tympanic Membrane in Normal and Experimentally Simulated Pathological Ears

“…Over the past decade, various non-invasive optical methods, for example, holographic interferometric methods, were developed to quantify TM dynamics such as excitation-induced displacements, and physical characteristics such as shape and thickness [11,[16][17][18][19][20][21][22][23][24][25][26]. However, a study on the live subject remains challenging due to the natural noise, such as motions due to respiration, heartbeat, muscle tremor, etc.…”

Combined high-speed holographic shape and full-field displacement measurements of tympanic membrane

“…Over the past decade, various holographic methodologies were developed to quantify TM functional parameters such as excitation induced displacements, shape, and thickness. 11,[18][19][20][21][22][23][24][25][26][27][28] One of the main challenges in holographic measurements of TM acoustically induced nanometer-scale motions is the high sensitivity to physiological motions (micrometer to submillimeter) in live ears (motions due to respiration, heartbeat, muscle tremor, etc.). To solve this problem, high-speed digital holographic (HDH) methods were developed to measure the TM motions produced by brief acoustic transients (click response with duration of <5 ms).…”