Photoacoustic effect

The photoacoustic effect (PAE), also called optoacoustic effect , is a physical effect that optoacoustics makes use of. It describes the conversion of light energy into acoustic energy ( sound ). The photoacoustic effect was first described in 1880 by Alexander Graham Bell . Shortly thereafter, other well-known scientists such as Rayleigh , Wilhelm Conrad Röntgen and John Tyndall published work on this effect.

description

If a propagation medium is irradiated with light, part of the light energy is absorbed by the medium and converted into thermal energy. Due to the heat conduction , the energy is distributed in the medium after a finite time and a minimally increased temperature is set in the medium (heat losses through thermal radiation etc. are not considered for the sake of simplicity). The supply of heat leads to an increase in volume or a decrease in density .

If the medium is irradiated with a series of flashes of light , periodic heating and “cooling” occur. This constant alternation of volume expansion and reduction represents a source of sound . This can be structure-borne sound in solid bodies or normal sound in gas.

application

The photoacoustic effect is used, among other things, in photoacoustic spectroscopy and photoacoustic tomography for the examination of gases , solids and tissues .

literature

Harald Leyser: Time-resolved calorimetry for the investigation of structural and reactive dynamics in proteins . Herbert Utz Verlag, 1999, ISBN 978-3-89675-588-9 ( limited preview in Google book search).
Allan Rosencwaig: Photoacoustic Spectroscopy . In: L. Marton (Ed.): Advances in electronics and electron physics . Academic Press, 1978, ISBN 978-0-12-014646-8 , pp. 208–313 (contains a good section on the history of the photoacoustic effect).

Web links

A Flashlight playing the Imperial March (YouTube) Demonstration of the photoacoustic effect on microfiber fabrics

Individual evidence

^ A. G Bell: On the production and reproduction of sound by light . In: Am. J. Sci . tape 20 , no. 118 , 1880, pp. 305-324 .
↑ Lord Rayleigh: The Photophone . In: Nature . tape 23 , 1881, p. 274-275 , doi : 10.1038 / 023274a0 .
^ WC Roentgen: On tones produced by the intermittent irradiation of a gas . In: Philosophical Magazine Series 5 . tape 11 , no. 68 , 1881, p. 308-311 .
^ John Tyndall: Action of an Intermittent Beam of Radiant Heat upon Gaseous Matter . In: Proceedings of the Royal Society of London . tape 31 , 1880, p. 307-317 , JSTOR : 114062 .
^ Markus W. Sigrist: Air monitoring by spectroscopic techniques . Wiley-IEEE, 1994, ISBN 978-0-471-55875-0 , pp. 163 .
↑ Darryl Almond, Pravin Patel: Photothermal science and techniques . Springer, 1996, ISBN 978-0-412-57880-9 , pp. 4 .

[1] A. G Bell: On the production and reproduction of sound by light . In: Am. J. Sci . tape 20 , no. 118 , 1880, pp. 305-324 .

[2] Lord Rayleigh: The Photophone . In: Nature . tape 23 , 1881, p. 274-275 , doi : 10.1038 / 023274a0 .

[3] WC Roentgen: On tones produced by the intermittent irradiation of a gas . In: Philosophical Magazine Series 5 . tape 11 , no. 68 , 1881, p. 308-311 .

[4] John Tyndall: Action of an Intermittent Beam of Radiant Heat upon Gaseous Matter . In: Proceedings of the Royal Society of London . tape 31 , 1880, p. 307-317 , JSTOR : 114062 .

[5] Markus W. Sigrist: Air monitoring by spectroscopic techniques . Wiley-IEEE, 1994, ISBN 978-0-471-55875-0 , pp. 163 .

[6] Darryl Almond, Pravin Patel: Photothermal science and techniques . Springer, 1996, ISBN 978-0-412-57880-9 , pp. 4 .