由于KDP（KH2PO4）晶体硬度低的特性，在利用单点金刚石切削技术对其进行加工的过程中，所使用的真空吸盘夹具会在其加工表面产生周期性波纹。周期性波纹在强激光非线性效应的作用下，不但会严重影响输出光束的质量，甚至还会破坏光学元件。因此，利用功率谱密度检测KDP晶体的加工表面，分析误差源，并指导加工工艺的改进。最后得出结论：在利用单点金刚石切削技术加工KDP晶体时，应根据不同的加工方式选择不同形状的真空吸槽作为夹具，尽量避免在垂直切削方向上使用真空吸槽吸附晶体，以减小吸槽的吸附力对晶体加工表面的影响。

Because KDP crystal is a soft material, when it is machined by single point diamond turning, vacuum chuck will result in surface waviness on crystal′s surface. Surface waviness will seriously affect the quality of high power laser beam, or even destroy optical elements, due to the nonlinear effect of high power laser. In order to improve the ultra-precision machining of KDP crystal, power spectral density is used to detect the machined surface of KDP crystal, and to analyze error sources. It is discovered that processing methods should be chosen according to the shape of vacuum chuck, and the use of vacuum chuck should be avoid in the vertical direction.