Study On Surface Figure Metrology Of Typical High Energy Laser Optics

Developing high energy laser systems is now increasingly becoming the focus of world science and technology competition.Convex aspheres,cylinders and even free-from surfaces with high precision are more and more required.Deterministic figuring is an inevitable trend for fabricating these complex surfaces to high precision,and the premise of deterministic figuring is to obtain the correct surface error map of the workpiece surface.Convex aspheres and cylinders are both representatives of optics difficult to test in the high energy laser systems,and surface figure metrology for them is studied in this thesis.This thesis comprises three parts of contents:1.In situ calibrated null test of convex aspheres.A large-aperture aspheric null lens is designed as usual to balance the aberrations of the convex asphere.The transmitted wavefront error is then calibrated by another small-aperture null lens assembly.The calibration is performed in situ,i.e.,the test beam travels the same path in the aspheric null lens as it is used for test of the convex asphere.Consequently the error induced by material inhomogeneity,material defects of the aspheric null is removed from the surface figure result of the test convex asphere.The measurement uncertainty is finally traced back to the small-aperture calibration null lens.2.CGH null test for cylindrical mirrors.The CGH design method for cylindrical mirrors and the relationship between the misalignment aberrations and alignment errors are studied.On this basis,the QED stitching algorithm is modified to meet the special requirements of stitching cylindrical surfaces.The simulation and experiment results show that this modified algorithm can realize the stitching of cylindrical surfaces with good accuracy.3.Near null subaperture stitching method for cylindrical mirrors is studied.The near null subaperture stitching method has great advantages for testing aspherical cylinders,and it is promising to break through the bottleneck of limited aperture in null test and limited aspheric departure in subaperture test.