ABSTRACT
The development of high-power lasers requires optics with very low absorption to avoid detrimental thermal effects. In this work, we discuss our recent developments on the use of lock-in thermography to measure absorption. We apply this technique in a multipass configuration to increase the effective power on the tested samples. We present a system based on a kW-class ytterbium fiber laser operating at 1.07 µm wavelength, which enables exposing samples to 5 kW effective power and measuring absorption in the ppm range. The implementation, calibration procedure, and obtained performance are discussed with some applications to single-layer coatings of HfO2,Ta2O5,TiO2,Nb2O5, and SiO2 deposited by plasma-assisted electron beam deposition.
ABSTRACT
The possibility of enhanced mirrors for laser megajoule reflectors has been studied, and preliminary samples have been realized with magnetron sputtering technology. Spectral measurements of improved reflectivity and cosmetics analysis are presented.