Thermally induced lensing determination from the coefficient of defocus aberration

Abstract

The effects of a temperature gradient in a laser crystal in an end-pumped configuration in a solid-state laser resonator results in thermally induced aberrations. Of particular interest we measure the thermally induced lens from the coefficient of defocus aberration with a Shack- Hartmann wavefront sensor. As a calibration technique, we infer the focal length of standard lenses probed by a collimated Gaussian beam at 633 nm and this technique is applied to an Nd:YAG medium under active pumping. This result is compared to a typical thermal lens determination where the length of an unstable cavity is varied.