Fig. 1. Flow chart of non-null stitching test of convex aspheric metal mirror

Fig. 2. Schematic diagram of test principle of convex aspheric metal mirror. (a) Schematic diagram of aspheric surface test; (b) Schematic diagram of standard mirror selection

Fig. 3. Asphericity of the tested mirror. (a) Calculation result of the asphericity of the tested mirror; (b) Full-aperture Slope analysis result

Fig. 4. Schematic diagram of sub-aperture plan

Fig. 5. Surface shape of various sub-aperture and interference fringe simulation results. (a) Central sub-aperture wavefront; (b) Central sub-aperture interference fringe; (c) Second circle aperture wavefront; (d) Second circle aperture interference fringe

Fig. 6. Test light path of convex aspheric metal mirror

Fig. 7. Stitching test results. (a) Center sub-aperture test results; (b)-(e) Peripheral sub-aperture test results; (f) Full-aperture surface shape after stitching

Fig. 8. Metal mirror shape error. (a) Stitching test result; (b) Luphoscan test result; (c) Residual difference between sub-aperture stitching test result and Luphoscan test result