Under The Triple Frequency Laser Metal Particles To Research On The Effects Of Fused Quartz Component Damage Threshold

In high power laser, the resistance of optics to laser damage has become the bottleneck problem to limit the high average power output. Metal particle, which is one of contaminations on the fused silica, has been drawn much attention to on the effect of the element life, and it lower the LIDT and shorten the lifetime of optics. Therefore, it is very important to study the mechanism of the laser damage induced by the surface metal particle contamination of fused silica, in order to enhance the resistance to damage and prolong the serviceable lifetime.This thesis mainly focus on the influence of metal particles on damage threshold of fused silica by the method of comparative experiments, and the temperature variation and electromagnetic field distribution in the damage process were simulated. The mainly contents and conclusions are as follows:(1) Damage threshold of several different fused silica components were measured, and a number of factors that affect the damage threshold are summarized by analyzing the experimental results and the difference of the experimental phenomena. The standard damage-test platform of Film Center in SIOM was used; the testing standards of ISO11254was deepen understanding and some problems in the course of damage-test.(2) Fused silica components contaminated by metal particles were measured and found that the damage threshold was greatly reduced; the progress of damage can be speculated by observing the different images between polluted and unpolluted fused silica that has been damaged. The probability of damage can be recognized by the statistics of a large number of metal particles damage; the impact of spot size to the result of damage-test was deduced based on the damage probability model.(3) In addition to the damage threshold of fused silica, the damage threshold of some metallic materials were also measured. It is found that the threshold of metallic materials are much lower than that of fused silica; laser irradiation to the metal surface can easily lead to metal particles, so a reasonable optical arrangement to prevent the laser irradiation to the metal surface is very important; the threshold of some different aluminum alloy under different treatments provides a basis for the selection of metal in high-power laser.(4) Heat absorption of metal particles was analyzed and the temperature change of metal particles was simulated, it is found that the heating of the metal particle is an instantaneous process and the components are easily damaged; the electric field distribution of damaged point was calculated by FDTD and the simple two-dimensional model was simulated, it is found that defects points has a strong role in the modulation of light field, the local incident field can be more than twice, which make the defects easy to grow.