When nonlinear optical and laser technology components are exposed to high (laser) light intensities, even very low levels of absorption may lead to local heating, eventually resulting in component malfunctions or even damage. It is essential to detect these minimal absorptions, which do occur even in highly pure materials, before the components are used. This requires extremely sensitive measuring processes. Fraunhofer IPM uses two such processes to verify the amount of absorbed energy.
Photoacoustic spectroscopy (PAS)
The principle of photoacoustic spectroscopy implies that high-frequent acoustic waves are generated within the material by using a pulsed laser (photoacoustic effect). A sensitive piezoelectric sensor detects the acoustic waves. The intensity of absorption is concluded from the amplitude of the sound wave.