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.
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/cm<sup>2</sup> 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.
Damage tests were carried out to measure the laser resistance of Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub> and Al<sub>2</sub>O<sub>3</sub>/HfO<sub>2</sub>
antireflection coatings at 1064nm grown by atomic layer deposition (ALD). The S-on-1 and
R-on-1 damage results are given. It's interesting to find that ALD coatings damage performance
seems closed to those grown by conventional e-beam evaporation process. For Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub>
coatings, the grown temperature will impact the damage resistance of thin films. Crystallization of
TiO<sub>2</sub> layer at higher temperature could play an importance role as absorption defects that reduced
the LIDT of coatings. In addition, it is found that using inorganic compound instead of organic
compound as precursors for ALD process can effective prevent residual carbon in films and will
increase the LIDT of coatings.
Generally, substrates in a planetary rotation system result in coatings with nonuniformity of 2% or greater over apertures of 500mm. However, more accurate, uniform deposition of large-aperture optical coatings is required now. So it is very important to study how to improve the deposition uniformity of large-aperture optical coatings. In this paper, we show that a theoretical model that can forecast the thickness distributions of films, get precise figure of masks, and should optimize the deposition uniformity accurately and fast through fixing the designed masks in the chamber.