中国物理B ›› 2012, Vol. 21 ›› Issue (5): 50301-050301.doi: 10.1088/1674-1056/21/5/050301

• • 上一篇    下一篇

Mechanism of micro-waviness induced KH2PO4 crystal laser damage and the corresponding vibration source

李明全1,陈明君1,安晨辉2,周炼2,程健1,肖勇1,姜伟1   

  1. 1. Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001, China;
    2. Chengdu Fine Optical Engineering Research Center, Chengdu 610041, China
  • 收稿日期:2011-03-14 修回日期:2012-04-27 出版日期:2012-04-01 发布日期:2012-04-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No. 50875066).

Mechanism of micro-waviness induced KH2PO4 crystal laser damage and the corresponding vibration source

Li Ming-Quan(李明全)a), Chen Ming-Jun(陈明君)a)†, An chen-Hui(安晨辉)b), Zhou Lian(周炼)b), Cheng Jian(程健)a), Xiao Yong(肖勇)a), and Jiang Wei(姜伟)a)   

  1. a. Center for Precision Engineering, Harbin Institute of Technology, Harbin 150001, China;
    b. Chengdu Fine Optical Engineering Research Center, Chengdu 610041, China
  • Received:2011-03-14 Revised:2012-04-27 Online:2012-04-01 Published:2012-04-01
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No. 50875066).

摘要: The low laser induced damage threshold of the KH2PO4 crystal seriously restricts the output power of inertial confinement fusion. The micro-waviness on the KH2PO4 surface processed by single point diamond turning has a significant influence on the damage threshold. In this paper, the influence of micro-waviness on the damage threshold of the KH2PO4 crystal and the chief sources introducing the micro-waviness are analysed based on the combination of the Fourier modal theory and the power spectrum density method. Research results indicate that among the sub-wavinesses with different characteristic spatial frequencies there exists the most dangerous frequency which greatly reduces the damage threshold, although it may not occupy the largest proportion in the original surface. The experimental damage threshold is basically consistent with the theoretical calculation. For the processing parameters used, the leading frequency of micro-waviness which causes the damage threshold to decrease is between 350-1 μ-1 and 30-1 μ-1, especially between 90-1 μ-1 and 200-1 μ-1. Based on the classification study of the time frequencies of micro-waviness, we find that the axial vibration of the spindle is the chief source introducing the micro-waviness, nearly all the leading frequencies are related to the practical spindle frequency (about 6.68 Hz, 400 r/min) and a special middle frequency (between 1.029 Hz and 1.143 Hz).

关键词: laser induced damage threshold, micro-waviness, Fourier modal theory, power spectrum density

Abstract: The low laser induced damage threshold of the KH2PO4 crystal seriously restricts the output power of inertial confinement fusion. The micro-waviness on the KH2PO4 surface processed by single point diamond turning has a significant influence on the damage threshold. In this paper, the influence of micro-waviness on the damage threshold of the KH2PO4 crystal and the chief sources introducing the micro-waviness are analysed based on the combination of the Fourier modal theory and the power spectrum density method. Research results indicate that among the sub-wavinesses with different characteristic spatial frequencies there exists the most dangerous frequency which greatly reduces the damage threshold, although it may not occupy the largest proportion in the original surface. The experimental damage threshold is basically consistent with the theoretical calculation. For the processing parameters used, the leading frequency of micro-waviness which causes the damage threshold to decrease is between 350-1 μm-1 and 30-1 μm-1, especially between 90-1 μm-1 and 200-1 μm-1. Based on the classification study of the time frequencies of micro-waviness, we find that the axial vibration of the spindle is the chief source introducing the micro-waviness, nearly all the leading frequencies are related to the practical spindle frequency (about 6.68 Hz, 400 r/min) and a special middle frequency (between 1.029 Hz and 1.143 Hz).

Key words: laser induced damage threshold, micro-waviness, Fourier modal theory, power spectrum density

中图分类号:  (Other special classical field theories)

  • 03.50.Kk
42.62.Eh (Metrological applications; optical frequency synthesizers for precision spectroscopy) 42.70.Mp (Nonlinear optical crystals) 42.79.Nv (Optical frequency converters)