Fig. 1. Schematic diagram of curvature sensing

Fig. 2. Co-focus detection method of sparse aperture telescope based on curvature sensing

Fig. 3. Large amplitude wavefront tilt sensing. (a) Tilt wavefront; (b) Reconstruction wavefront; (c) Intensity distribution before focus; (d) Intensity distribution after focus

Fig. 4. Small amplitude wavefront tilt. (a) Tilt wavefront; (b) Reconstruction wavefront; (c) Intensity distribution intra-focus; (d) Intensity distribution extra-focus

Fig. 5. Perception and regulation of overall low order aberrations of sub mirror. (a) Tilt wavefront; (b) Reconstruction wavefront; (c) Intensity distribution intra-focus; (d) Intensity distribution extra-focus

Fig. 6. Verification platform for wavefront tilt calculation using deformable mirror

Fig. 7. Verification results of distortion perception of boundary using deformable mirror. (a) Intensity distribution intra-focus; (b) Intensity distribution extra-focus; (c) Wavefront solution results; (d) Low order aberration; (e) Low order aberration estimation

Fig. 8. Correlation coefficient of wavefront tilt solution. (a) Initial condition; (b) First correction; (c) Second correction; (d) Third correction

Fig. 9. Closed loop correction process. (a) System diagram; (b) Optical intensity difference before and after focus