Light distribution measurements in absorbing materials by optical detection of laser‐induced stress waves
作者:
G. Paltauf,
H. Schmidt‐Kloiber,
H. Guss,
期刊:
Applied Physics Letters
(AIP Available online 1996)
卷期:
Volume 69,
issue 11
页码: 1526-1528
ISSN:0003-6951
年代: 1996
DOI:10.1063/1.117993
出版商: AIP
数据来源: AIP
摘要:
A method for optimized generation and detection of thermoelastic stress waves for the measurement of tissue optical properties and structure is investigated. The stress waves are formed by short pulsed irradiation of an absorbing dye solution with aQ‐switched Nd:YAG laser at 532 nm. An optical transducer based on pressure‐induced reflectivity changes of a continuous laser beam at a glass‐water interface detects the stress wave in front of the irradiated sample surface. It is shown theoretically and experimentally that this kind of detector, where the active area is a small spot close to the irradiated surface, minimizes signal distortion due to acoustic diffraction. Comparisons of absorption coefficients measured acoustically and from optical transmission show a good agreement between the two methods. The high sensitivity of the detector (1.5 mV/bar) makes it possible to keep the temperature and pressure rise in the investigated target low, which enablesinvivoapplications of the optical transducer. ©1996 American Institute of Physics.
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