The new sandwich concept for absolute photo-thermal absorption measurements using the laser induced deflection (LID)
technique is introduced and tested in comparison to the standard LID concept.
The sandwich concept’s idea is the decoupling of the optical materials for the pump and probe beams by placing a
sample of investigation in between two optical (sandwich) plates. The pump beam is guided through the sample whereas
the probe beams are deflected within the sandwich plates by the thermal lens that is generated by heat transfer from the
Electrical simulation and laser experiments reveal that using appropriate optical materials for the sandwich plates, the
absorption detection limit for photo-thermally insensitive materials can be lowered by up to two orders of magnitude.
Another advantage of the sandwich concept, the shrinking of the currently required minimum sample size, was used to
investigate the laser induced absorption change in a Nd:YVO<sub>4</sub> crystal at 1030nm. It was found that the absorption in
Nd:YVO<sub>4</sub> lowers due to the laser irradiation but partially recovers during irradiation breaks. Furthermore, absorption
spectroscopy has been performed at two LBO crystals in the wavelength range 410...600nm to study the absorption
structure around the SHG wavelengths of common high power lasers based on Neodymium doped laser crystals.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Ch. Mühlig ; S. Bublitz and W. Paa
"Sandwich concept: enhancement for direct absorption measurements by laser-induced deflection (LID) technique", Proc. SPIE 8530, Laser-Induced Damage in Optical Materials: 2012, 85301X (December 6, 2012); doi:10.1117/12.976853; http://dx.doi.org/10.1117/12.976853