大口径非球面的超精密回转扫描测量技术研究

Study of ultra-precise rotary scanning measuring technique for large aspheric surface

分析了基于衍射准直技术的f-θ透镜系统特性,进而提出一种大口径非球面轮廓测量方法。以二维相位板生成的衍射准直光束为测量基准光束,并以衍射光斑的暗线为位移基准,通过将超精密直线运动和超精密回转运动有机合成,实现了对大口径近平面非球面三维轮廓的回转扫描测量。研制出了实验样机,可测量的大口径非球面直径达500 mm,单点稳定性优于1μrad/200 s,与AK100Fizeau干涉仪的比对测量结果为PV值=0.1λ和RMS值=0.05λ,验证了本文提出的方案能够胜任大口径近平面非球面的三维轮廓检测,为将顺序扫描法拓展至大口径范围深度非球面轮廓测量提供了坚实的理论基础。

Characters of f-θ lens system are analyzed based on diffractive collimation technique and a kind of profile measuring method of large aspheric surface is put forward.The diffractive collimation beam produced by two-dimensional phase plate is the measuring base and the dark line of diffractive spot is displacement base.Through combining ultra-precise line motion with ultra-precise rotary motion,the three-dimensional profile of large hither plane aspheric surface is obtained by rotary scanning measuring.The experimental prototype is developed,its biggest measuring range of large aspheric surface diameter is 500 mm and stability of single spot is better than 1 μrad/200 s.Comparing with AK100 Fizeau interferometer,the measuring results are as follows：PV=0.1λ,RMS=0.05λ.It is demonstrated that the three-dimensional profile of large hither plane aspheric surface may be obtained by measuring of large aspheric surface based on ultra-precise rotary scanning.