对晶体光损伤阈值测量的一种新方法的研究

提出一种测量晶体光损伤阈值的新方法，即确定激光横向功率密度的空间分布，利用晶体的激光损伤斑点半径，直接计算出晶体光损伤阈值，并给出入射激光为高斯光束时晶体损伤阈值与其损斑半径的关系。以提拉法生长的掺镁铌酸锂(MgO：LiNbO3)晶体为研究对象，用该方法测量其损伤阈值，得到了定量结果且所得数据与文献已报道的规律相符。分析得出同样激光条件下．损斑半径越大的晶体其光损伤阈值越小的结论，指出该方法同样适用于其他晶体或非高斯光束条件下光损伤阈值的测量并对具体作法进行了讨论。该测量方法弥补了常用测量方法只能定性或半定量的不足，可用于晶体抗光损伤阈值的精确测量。

A Novel Method for Measuring the Laser Damage Threshold of Crystal

A novel method to measure the laser induced damage threshold (LIDT) of crystals is presented. The method involves confirming the cross-sectional power density distribution of incident laser and measuring crystals' radii of damage spots, then calculating the corresponding LIDT. For Gaussian laser beam, a relational expression between crystals' damage threshold and radius of damage spots has been reasoned out. Different from other measuring method, this new method can qualitatively and exactly measure crystals' laser induced damage threshold. Using the method, the laser induced damage thresholds of LiNbO3 single crystals doped with different MgO concentration are measured under the same laser condition. The measuring results agree well with both former relevant reports and authors′ theoretical analysis. The applicability of the new method is discussed. It is shown that the proposed method is fast, accurate and can be widely used to precisely test crystals' laser induced damage threshold.