TY - JOUR
T1 - Application of light diffraction theory to qualify the downstream light field modulation property of mitigated KDP crystals
AU - Yang, Hao
AU - Cheng, Jian
AU - Liu, Zhichao
AU - Liu, Qi
AU - Zhao, Linjie
AU - Tan, Chao
AU - Wang, Jian
AU - Chen, Mingjun
PY - 2021/6/30
Y1 - 2021/6/30
N2 - Micro-milling can effectively remove laser damage sites on a KDP (potassium dihydrogen phosphate) surface and then improve the laser damage resistance of the components. However, the repaired KDP interfaces could cause light propagating turbulence and downstream light intensification with the potential risk to damage downstream optics. In order to analyze the downstream light field modulation caused by Gaussian mitigation pits on KDP crystals, a computational model of the downstream light diffraction based on the angular spectrum theory and the Gaussian repair contour is established. The results show that the phase offset caused by the repaired surface produces a large light field modulation near the rear KDP surface. The modulation generated in the whole downstream light field is greater than that caused by the amplitude change. Therefore, the phase characteristics of the outgoing light could be suggested as a vital research topic for future research on the downstream light field modulation caused by mitigation contours. Significantly, the experimental results on the downstream light intensity distribution have good agreement with the simulation ones, which proves the validity of the established downstream light diffraction model. The phase characterization of the outgoing light is proposed as an evaluation tool in the repair of KDP crystals. The developed analytical method and numerical discrete algorithm could be also applicable in qualifying the repair quality of other optical components applied in high-power laser systems.
AB - Micro-milling can effectively remove laser damage sites on a KDP (potassium dihydrogen phosphate) surface and then improve the laser damage resistance of the components. However, the repaired KDP interfaces could cause light propagating turbulence and downstream light intensification with the potential risk to damage downstream optics. In order to analyze the downstream light field modulation caused by Gaussian mitigation pits on KDP crystals, a computational model of the downstream light diffraction based on the angular spectrum theory and the Gaussian repair contour is established. The results show that the phase offset caused by the repaired surface produces a large light field modulation near the rear KDP surface. The modulation generated in the whole downstream light field is greater than that caused by the amplitude change. Therefore, the phase characteristics of the outgoing light could be suggested as a vital research topic for future research on the downstream light field modulation caused by mitigation contours. Significantly, the experimental results on the downstream light intensity distribution have good agreement with the simulation ones, which proves the validity of the established downstream light diffraction model. The phase characterization of the outgoing light is proposed as an evaluation tool in the repair of KDP crystals. The developed analytical method and numerical discrete algorithm could be also applicable in qualifying the repair quality of other optical components applied in high-power laser systems.
KW - Downstream light field modulation
KW - Laser damage
KW - Micro-milling
KW - Surface damage mitigation
UR - https://arxiv.org/abs/2008.10047
UR - https://www.sciencedirect.com/journal/optics-and-laser-technology
U2 - 10.1016/j.optlastec.2020.106873
DO - 10.1016/j.optlastec.2020.106873
M3 - Article
AN - SCOPUS:85099483941
SN - 0030-3992
VL - 138
JO - Optics and Laser Technology
JF - Optics and Laser Technology
M1 - 106873
ER -