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Proceedings Paper

Characterization of laser-induced pressure transients by means of piezoelectric PVDF films
Author(s): Stefan Lohmann; Andreas Olmes; Holger Lubatschowski; Wolfgang Ertmer
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Paper Abstract

For an interpretation of pressure signals detected by piezoelectric PVDF-foils several parameters are of importance. These are for example pressure pulse duration and rise times, active area of the film and specifications concerning the high-frequency technique of the experimental setup. Using an input-resistance of 1 M(Omega) at the storage-oscilloscope leads to reflections of the signal which superimpose each other when reflected a second time at the foil. This might cause an apparent increase of the amplitude. The utilization of a longer cable allows a separation of each reflected pulse, but it causes the problem, that the cable's input- impedance approaches its characteristic impedance of 50 (Omega) . This will lead to a time derived signal as well as using 50 (Omega) as input-resistance at the scope. Therefore a direct measurement of short pressure transients requires a very short cable and an input-resistance of 1 M(Omega) . Otherwise the measured signal allows no proportional relation between pressure transient and measured voltage signal. In the latter case a frequency-dependent correction of the signal becomes necessary. This has been developed in this paper by means of Fast Fourier Transform algorithm. After correction in the frequency-domain the signal is transformed back into the time-domain.

Paper Details

Date Published: 10 January 1996
PDF: 10 pages
Proc. SPIE 2624, Laser-Tissue Interaction and Tissue Optics, (10 January 1996); doi: 10.1117/12.229541
Show Author Affiliations
Stefan Lohmann, Univ. Hannover (Germany)
Andreas Olmes, Univ. Hannover (Germany)
Holger Lubatschowski, Univ. Hannover and Laserzentrum Hannover (Germany)
Wolfgang Ertmer, Univ. Hannover (Germany)


Published in SPIE Proceedings Vol. 2624:
Laser-Tissue Interaction and Tissue Optics
Guy P. Delacretaz; Rudolf W. Steiner; Lars Othar Svaasand; Hansjoerg Albrecht; Thomas H. Meier, Editor(s)

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