Photothermal lensing detection: theory and experiment

Photothermal lensing signal shapes are experimentally investigated and compared with those predicted theoretically in our earlier paper. The investigation included flowing and stationary media and pulsed and cw excitations. Good qualitative agreement between theory and experiment is found. Since the lensing signal is almost always accompanied by a deflection signal, the influence of the deflection signal on the detection of lensing signal is investigated. For a perfectly aligned detection geometry the influence of the deflection signal on the lensing signal is negligible, but in the presence of misalignments lensing on the deflection signal is also been considered. The effect of the finite size of the probe beam on the lensing signals is also investigated. (C) 1997 Optical Society of America.