8 ITMP3 / 8éme conférence internationale de photoacoustique et photothermique
J. Phys. IV France 04 (1994) C7-43-C7-46
A differential photoacoustic imaging systemC.A. Hall1, A.W. Williams1 and N.J. Wood2
1 Department of Physics, University College Swansea, University of Wales, Singleton Park, Swansea SA2 8PP, U.K.
2 Department of Aeronautics and Astronautics, University of Southampton
We describe a differential photoacoustic (PA) imaging system in which almost equal intensity beams modulated 180° out of phase illuminate two regions of a sample in a PA cell. For two regions that are both optically and thermally similar and also homogeneous, the resulting signal is almost zero but if one region has a sub-surface defect this will give an increased signal. This differential signal has a much higher signal to noise ratio than conventional PA systems.
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