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Optoacoustic (or photoacoustic) methods have long been used to measure absorption of light in samples that also scatter light significantly (for example, Tam 1986, Patel and Tam 1981). In these methods, a sample is illuminated by a short pulse of light or by a light beam with modulated irradiance. Absorption of light in a zone of the sample illuminated by the beam causes a momentary temperature, and hence a pressure rise in that zone. The pressure rise propagates through the sample as an acoustic wave whose amplitude is related to the absorption coefficient of the sample.
Applications of optoacoustic methods range from measurements of the absorption of light by water (for example, Tam and Patel 1979), through measurements of the absorption of light by aerosols (for example, Arnott et al 1999, Terhune and Anderson 1977), to absolute calibration of photodiodes (for example, Halaska et al 1993). Schleusener et al (1976) describe a "low-frequency" version of the optoacoustic method in which the pressure difference between a reference chamber and a sample chamber, both illuminated by the same light beam, is measured after a steady state is reached.
See also Absorption of light in turbid media: Photothermal deflection spectroscopy.
| CITATION: Jonasz M. 2006. Absorption of light in turbid media: Optoacoustic measurement methods (www.tpdsci.com/Tpc/AbsOptAco.php). In: Top. Part. Disp. Sci. (www.tpdsci.com). |
HISTORY: Published: 25-May-2006 Modified: 24-May-2007 Reviewed: PENDING |
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