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'