Fig. 1. Schematic of coordinate transformation of off-axis parabolic mirror

Fig. 2. Flowchart of search algorithm closest to sphere

Fig. 3. Three-dimensional simulation results of off-axis parabolic mirror. (a) Vector height of off-axis paraboloid; (b) vector height of best fitting sphere; (c) removal amount of sphere turning off-axis paraboloid; (d) asphericity curve

Fig. 4. Initial spherical mirror

Fig. 5. Surface shape subtraction diagram after line scanning processing. (a) 2D diagram; (b) 3D diagram

Fig. 6. Etching depth diagram on MATLAB

Fig. 7. Surface diagram of one-time surface scanning

Fig. 8. Surface diagram of batch sub-surface scanning

Fig. 9. Simulation results of batch machining of spherical off-axis paraboloid mirror. (a) Two-dimensional distribution of initial spherical error of concave spherical mirror; (b) three-dimensional distribution of initial spherical error of concave spherical mirror; (c) total material removal; (d) 10% residence time; (e) 20% residence time; (f) 70% residence time

Fig. 10. Schematic of detection light path of off-axis parabolic mirror

Fig. 11. Inspection diagram of off-axis parabolic mirror

Fig. 12. Surface shape detection results of off-axis parabolic mirror after three iterations. (a) Test results after 1^st processing; (b) test results after 2^nd processing; (c) test results after 3^rd processing

Fig. 13. Physical diagram of ion source aperture

Fig. 14. Test results of surface shape after machining of small beam diameter

Fig. 15. Analysis results of local high point ion beam modification base surface. (a) Surface shape detection and pick-up figure 1; (b) surface shape detection and pick-up figure 2; (c) surface shape detection and pick-up figure 3

Fig. 16. Simulation results of regularized base surface removal

Fig. 17. Detection results of final surface shape of off-axis parabolic mirror

Table 1. Process parameters for stable operation of ion source