Optoacoustic measurements of water, bone, and cartilage with an infrared OPO

Kornel P. Koestli; Martin Frenz; Heinz P. Weber; Guenther Paltauf; Heinz Schmidt-Kloiber

doi:10.1117/12.350014

14 June 1999 Optoacoustic measurements of water, bone, and cartilage with an infrared OPO

Kornel P. Koestli, Martin Frenz, Heinz P. Weber, Guenther Paltauf, Heinz Schmidt-Kloiber

Proceedings Volume 3601, Laser-Tissue Interaction X: Photochemical, Photothermal, and Photomechanical; (1999) https://doi.org/10.1117/12.350014
Event: BiOS '99 International Biomedical Optics Symposium, 1999, San Jose, CA, United States

Abstract

Optoacoustical signals generated with infrared laser pulses were studied. Thereby, the effective attenuation coefficient of cartilage and the absorption coefficient of water were measured for different wavelengths. The light-source used was an optical parametric oscillator (OPO) with a pulse duration of 5 ns. The OPO had a tuning range from 1500 to 3600 nm wavelength with a linewidth less than 30 nm. The absorption coefficient of water could be varied between 8 cm^-1 and 10⁴ cm^-1 by tuning the wavelength of the OPO. The laser induced stress transients were measured with an optical transducer. Measurements in transmission mode and reflection mode (transducer and incident OPO pulse are at opposite sides or at the same side of the sample, respectively) were compared. In reflection mode an infrared- transparent liquid was used to uncouple acoustical and thermal effects. The attenuation coefficient was determined by an exponential fit to the pressure signal. Cartilage and water absorptions were compared between 1860 nm and 1935 nm wavelength. For bone optoacoustical signals were measured between 1835 nm and 1935 nm. Optoacoustic measurements with an infrared OPO give the possibility to obtain optical properties of tissues over a wide wavelength range. Especially in reflection mode in vivo tissue characterization and medical diagnostics are possible.

Citation Download Citation

Kornel P. Koestli, Martin Frenz, Heinz P. Weber, Guenther Paltauf, and Heinz Schmidt-Kloiber "Optoacoustic measurements of water, bone, and cartilage with an infrared OPO", Proc. SPIE 3601, Laser-Tissue Interaction X: Photochemical, Photothermal, and Photomechanical, (14 June 1999); https://doi.org/10.1117/12.350014

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