To determine whether the mitigated KDP surface by micro-milling would potentially threaten downstream optics, we calculated the light field modulation based on the angular spectrum diffraction theory and performed the laser damage test on downstream fused silica. The results showed that the solved peak value of light intensification exceeded 6, which was caused by the Gaussian mitigation pit with 800 μm width and 10 μm depth. Then, it induced laser damage sites on the fused silica surface in the damage test. The study proves that the mitigated KDP surface can cause laser damage to the downstream optical components, which should be paid attention to in the actual application. Through this work, we find the current manufacture process and the mitigation index still need to be improved. Besides, the research methods and calculation models are also of great reference significance for related study like optics mitigation and laser damage.
Yang Hao, Cheng Jian, Liu Zhichao, Liu Qi, Zhao Linjie, Tan Chao, Wang Jian, Chen Mingjun. Potential damage threats to downstream optics caused by Gaussian mitigation pits on rear KDP surface[J]. High Power Laser Science and Engineering, , (): .
