The damage morphology change condition of 1064nm reflector under multi-shot was investigated. Two typical kind of damage, scald and delaminate, were careful characterized in the damage growth process by SEM. The scald damage tends to become delaminate damage under some certain condition. Huge experiments supports that this morphology change condition has a close connection with scald initial fluence, subsequent fluence and shot number. The relationship among these factors is for the first time achieved to offer the “safety lines” for components.
Laser-induced damages on optical components will cause wavefront modulation effect and further influence the downstream propagation of transmitted beam. In this paper, a method named polygon-binaryzation modeling (PBM) is applied to describe this effect taking place on dielectric coating. Both theoretical and experimental studies are carried out. In theory, the principle of PBM is introduced. Downstream beam propagation behind damage site could be simulated based on the wavefront model. In experiment, a pump-and-probe testing bench is designed. Wavefront properties of coating damages with opaque and transparent morphologies are detected. Furthermore, based on the experimental parameters, PBM is simulated. The good match between simulation and experiment demonstrates the validity of our method.
Proc. SPIE. 9142, Selected Papers from Conferences of the Photoelectronic Technology Committee of the Chinese Society of Astronautics: Optical Imaging, Remote Sensing, and Laser-Matter Interaction 2013
This paper concentrates on the measurement and analysis of laser ablation effect of particularly prepared aerospace material, polycarbosilane (PCS). Laser ablation experiment setup is designed and built, based on a continuous-wave high-power solid-state laser (CWHPSSL). Steel samples with composite PCS coating are prepared. After that, a group of laser ablation experiment is performed. The samples are shot by laser beam with thousands W/cm2 fluence. The results, including the ablation morphology and temperature data, is shown and discussed. Temperature data gives a good demonstration of thermal protection effect of composite coating, and in the meanwhile the morphological features in the ablated region reveal the principle of PCS laser-proof effect. Theoretical investigation has also been carried out. The temperature field is simulated based on Fourier equation of heat conduction, and the simulation result provides a good demonstration on thermal-proof effect of PCS coating layer during laser ablation process.
A new phase locking method for Master Oscillate Power Amplifier (MOPA) coherent combining system is proposed in
this paper. The algorithm called Stochastic Parallel Gradient Descent (SPGD) control is adopted to correct piston errors
and generate the feedback signals. The capability of this algorithm for coherent combining is demonstrated by simulation,
and the relative parameters which directly influence the algorithm's convergence are also analyzed.