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Wave field characterization for non-destructive assessment of elastic properties using laser-acoustic sources in fluids and eye related tissues

: Windisch, T.; Schubert, F.; Köhler, B.; Spörl, E.


Kundu, T. ; American Society of Mechanical Engineers -ASME-; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Health monitoring of structural and biological systems 2010 : 8 - 11 March 2010, San Diego
Bellingham, WA: SPIE, 2010 (SPIE Proceedings 7650)
ISBN: 978-0-8194-8065-1
Conference on Health Monitoring of Structural and Biological Systems <2010, San Diego/Calif.>
Conference Paper
Fraunhofer IZFP, Institutsteil Dresden ( IKTS-MD) ()

The age-related changes in the visco-elastic properties of the human lens are discussed with respect to presbyopia for a long time. All known measurement techniques are based on extracted lenses or are damaging the tissue. Hence, in vivo studies of lens hardness are not possible at the moment. To close this gap in lens diagnostics this project deals with an approach for a non-contact laser-acoustic characterization technique. Laser-generated wave fronts are reflected by the tissue interfaces and are also affected by the visco-elastic properties of the lens tissue. After propagating through the eye, these waves are recorded as corneal vibrations by laser vibrometry. A systematic analysis of amplitude and phase of these signals and the wave generation process shall give information about the interface locations and the tissues viscoelastic properties. Our recent studies on extracted porcine eyes proved that laser-acoustic sources can be systematically used for non-contacting generation and recording of ultrasound inside the human eye. Furthermore, a specific numerical model provides important contributions to the understanding of the complex wave propagation process. Measurements of the acoustic sources support this approach. Future investigations are scheduled to answer the question, whether this novel technique can be directly used during a laser surgery for monitoring purposes and if a purely diagnostic approach, e.g. by excitation in the aqueous humor, is also possible. In both cases, this technique offers a promising approach for non-contact ultrasound based eye diagnostics.