Effect of surface scallop tool marks generated in micro-milling repairing process on the optical performance of potassium dihydrogen phosphate crystal. (5th November 2018)

• Record Type: Journal Article
• Authors: Cheng, Jian; Xiao, Yong; Liu, Qi; Yang, Hao; Zhao, Linjie; Chen, Mingjun; Tan, Jiubin; Liao, Wei; Chen, Jing; Yuan, Xiaodong
• Is Part Of: Materials & design. Volume 157(2018)
• Page Start: 447
• Page End: 456
• Publication Date: 2018-11-05
• Subjects: Potassium dihydrogen phosphate crystal -- Surface damage repairing -- Micro-milling -- Periodic tool marks -- Laser damage resistance -- Light intensity distribution; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2018.07.057
• Languages: English
• ISSNs: 0264-1275

Abstract

Abstract: Micro-milling is the prevailing method to repair laser-induced surface damage on potassium dihydrogen phosphate crystal components applied in high-power laser systems. Scallop tool marks are inevitably generated on repaired surfaces due to the interaction of neighboring tool paths involved in the micro-milling process. In this work, the effect of scallop tool marks on the optical performance of micro-milled crystal surfaces is theoretically and experimentally investigated. The results indicate that surface tool marks could be categorized into four bands having different period lengths ( L ) according to the levels of induced light intensification: high-frequency (0.1 μm ≤ L ≤ 0.7 μm), high-risk (0.7 μm ≤ L ≤ 1.2 μm), intermediate-frequency (1.2 μm ≤ L ≤ 100 μm), and low-frequency (100 μm ≤ L ≤ 1000 μm) bands. Tool marks in high-risk band play dominant role in degrading the repairing effectiveness that they should be strictly excluded. While for intermediate-frequency band marks, the induced light intensification is low, and the laser damage resistance and transmittance capacity are comparable to those of tool mark-free surface. The experimental results agree well with simulation results, which suggest that machining parameters corresponding to tool marks in intermediate-frequency band should be preferred in the actual micro-milling repairing process. Graphical abstract: Unlabelled Image Highlights: Optical performance of repaired potassium dihydrogen phosphate is effectively evaluated by considering effect of tool marks. Surface tool marks with four typical period bands are identified according to the levels of induced light intensification. Tool marks with high-risk band seriously degrade optical performance with 87.3% transmittance and 60.7 J/cm 2 damage fluence. Repairing parameters corresponding to intermediate-frequency band tool mark are preferred to improve repairing effectiveness.