PHOTOTHERMAL ABSORPTION MEASUREMENTS

The thermal lensing effect

Due to unavoidable residual absorption, any optical element employed in high power laser systems is subject to thermal stress inside the optical material, giving rise to a transient wavefront distortion of the transmitted laser radiation. This effect known as „Thermal lensing“ leads to power dependent instabilities of laser processes, e.g. to a „Focus shift“ of optics used for laser material processing.

Thermal lensing effect

Quantitative measurements of 'thermal lensing'