建立KDP晶体与真空吸盘间有限元接触模型,并利用该模型分析吸气孔和吸气槽真空吸盘对KDP晶体面形精度的影响,分析了不同直径的吸气孔真空吸盘对KDP晶体变形的影响。结果表明:增大真空吸盘的占空比,可以减小完全吸附所需的真空度。吸气孔的直径越小,表面的变形越小。研究还发现,采用吸气孔吸附方式比采用吸气槽吸附方式可以得到更理想的面形质量。该结论对提高KDP晶体面形精度有着重要指导意义。利用超精密机床采用真空孔吸附方式加工KDP晶体,加工出面形精度为1/2X的表面。
A contacting model of KDP crystal attaching to vacuum chuck is established by finite element method to analyze the effects of vacuum chuck with hole and chuck with channel on the profile accuracy. Moreover, the influence of different hole in diameter of the vacuum chuck on the KDP crystal deformation is analyzed too. The result shows that the increase of vacuum ratios of vacuum chuck makes the vacuum degree of adsorption reduce. The smaller the vacuum chuck with hole diameter, the less the surface deformation. The study also discovered that vacuum chuck with hole is better than the that with channel on profile accuracy. The KDP crystal is machined by an ultra-precision machine tool and vacuum chuck with hole. Experimental result of profile accuracy is 1/2 wavelength.