title: Holographic otoscope for nanodisplacement measurements of surfaces under dynamic excitation.
abstract: We describe a novel holographic otoscope system for measuring nanodisplacements of objects subjected to dynamic excitation. Such measurements are necessary to quantify the mechanical deformation of surfaces in mechanics, acoustics, electronics, biology, and many other fields. In particular, we are interested in measuring the sound-induced motion of biological samples, such as an eardrum. Our holographic otoscope system consists of laser illumination delivery (IS), optical head (OH), and image processing computer (IP) systems. The IS delivers the object beam (OB) and the reference beam (RB) to the OH. The backscattered light coming from the object illuminated by the OB interferes with the RB at the camera sensor plane to be digitally recorded as a hologram. The hologram is processed by the IP using the Fresnel numerical reconstruction algorithm, where the focal plane can be selected freely. Our holographic otoscope system is currently deployed in a clinic, and is packaged in a custom design. It is mounted in a mechatronic positioning system to increase its maneuverability degrees to be conveniently positioned in front of the object to be measured. We present representative results highlighting the versatility of our system to measure deformations of complex elastic surfaces in the wavelength scale including a copper foil membrane and postmortem tympanic membrane. SCANNING 33: 342-352, 2011. © 2011 Wiley Periodicals, Inc.
authors: Center for Holographic Studies and Laser micro-mechaTronics, WPI, Worcester, MA 01609, USA. mflores@wpi.edu
authors: J M
authors: JM
authors: Flores-Moreno
authors: Cosme
authors: C
authors: Furlong
authors: John J
authors: JJ
authors: Rosowski
authors: Ellery
authors: E
authors: Harrington
authors: Jeffrey T
authors: JT
authors: Cheng
authors: C
authors: C
authors: Scarpino
authors: F Mendoza
authors: FM
authors: Santoyo
mesh_terms: D000162:Acoustics; D000818:Animals; D002682:Chinchilla; D004582:Electronics, Medical / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006696:Holography / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D010036:Otolaryngology / Q000379:methods; D019720:Otoscopes / Q000706:statistics & numerical data*; D012680:Sensitivity and Specificity; D014432:Tympanic Membrane / Q000502:physiology*; D014732:Vibration