Investigation of tympanic membrane shape using digital holography

The shape of the tympanic membrane (TM) plays an important role in sound transmission through the ear for hearing. Previously we developed a high-speed holographic system employing tunable wavelength laser for rapid TM shape measurement. However, the tunable laser illumination is not sufficient to measure the shape of the unpainted TM due to semi-transparency of the TM and short exposure time of the camera. This paper presents a new multiple angle illumination technique that allows us to use a single wavelength higher power laser to perform the shape measurement on the unpainted TM. We successfully applied the new shape measurement method on a fresh postmortem human TM without any paint.