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26 November 1996 Determination of optical properties by measuring laser-induced acoustic transients
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Time resolved measuring of laser induced acoustic transients is a good possibility for the determination of optical properties of tissue and tissue like samples. Laser radiation with perpendicular incidence upon the sample-air boundary causes a thermoelastic pressure distribution, which corresponds to the distribution of the absorbed energy in the sample. The knowledge of this distribution allows the determination of optical parameters. Acoustic transients are measured with an aluminum coated film of polyvinylidene fluoride (25 micrometers thickness). The geometric dimensions of the experimental set-up, such as the laser beam diameter, radial profile of the laser beam, penetration depth of radiation, position and size of the sensors are significantly influencing the profile of the measured transients. By using samples consisting of layers with different absorption coefficients, we can analyze the influence of diffraction on the profile of the acoustic signal. For simple geometric configurations it is possible to calculate the thermoelastic wave analytically, but for arbitrary configurations we are using a numerical procedure. The experimental results are qualitatively in good coincidence with our calculations.
© (1996) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Monika Kirschner, Guenther Paltauf, and Heinz Schmidt-Kloiber "Determination of optical properties by measuring laser-induced acoustic transients", Proc. SPIE 2928, Biomedical Systems and Technologies, (26 November 1996);

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