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Photoacoustics: An acoustic method for trace gas measurements
|Mehra, S.R.; Leistner, P. ; Deutsche Gesellschaft für Akustik -DEGA-, Berlin; Univ. Stuttgart, Lehrstuhl für Bauphysik; Fraunhofer-Institut für Bauphysik -IBP-, Stuttgart:|
Fortschritte der Akustik - DAGA 2007. CD-ROM : 33. Jahrestagung für Akustik, 19. bis 22. März 2007 in Stuttgart
Berlin: DEGA, 2007
S.505-506, Paper 000436
|Deutsche Jahrestagung für Akustik (DAGA) <33, 2007, Stuttgart>|
|Fraunhofer IBP ()|
The photoacoustic (or optoacoustic) effect, the generation of sound by the absorption of pulsed or modulated light has been known since the famous experiments of Alexander Graham Bell in 1880. Scientific and practical applications of the photoacoustic technique have been considerably promoted by the invention of laser, which is an almost ideal light source for photoacoustics. Recently, photoacoustic detectors play an increasing role in trace gas detection and analysis. The sensitivity of a small, simple and cheap photoacoustic detector is only slightly smaller than that of a very sophisticated and expensive optical system equipped with a multipass optical absorption cell and a cooled infrared detector. The performance of a photoacoustic trace gas detector depends mostly on its acoustical design. However, the majority of the published or commercially available photoacoustic detectors are acoustically not optimized. Considerable improvement in the sensitivity could be achieved byusing better acoustic designs and more sophisticated measurement and data evaluation methods. The PA research in the Fraunhofer Institute of Building Physics is targeted to the development of specific, acoustically optimized PA detectors for each important application fields of the PA technique, such as trace gas measurement and analysis in air; emission control of exhaust gases of vehicles and industrial combustion; detection of poisonous gases, drugs and explosives, monitoring and control of process gases, etc.