Measurement and simulation of wavefront deformation induced by a high-power CW laser in thin-film optical filters

High-power continuous-wave lasers are widely employed in industrial, defense, and research applications. Yet their interaction with optical thin-film components introduces challenges due to photo-induced thermal effects. This study investigates wavefront deformations arising from thermal gradients in thin-film optical filters under 1 µm high-power laser illumination. We implement an experimental platform that combines a high-resolution wavefront sensor in an imaging configuration with an infrared camera. The setup enables simultaneous mapping of optical path difference (OPD) and surface temperature on the same component during irradiation. Reflected and transmitted wavefront deformations are quantified, and a finite-element model reproduces the coupled thermo-elastic and thermo-optic response. The phase metrology coupled to a frequency filtering method demonstrates a sensitivity better than 2 nm in OPD for a 1 K temperature rise. Finite-element predictions agree with experiment over a 25 mm clear aperture, validating the methodology. By bridging synchronous measurements and modeling, the approach delivers a practical workflow for qualifying and optimizing thin-film components in high-power laser systems.