Fig. 1. Fundamental principles of fringe sampling. (a) System light-intensity sampling position and (b) sparse-aperture boundary multi-point sampling position

Fig. 2. Schematic diagram of fringe tracking sensing and control for the LASAT system

Fig. 3. Verification of the accuracy of the sparse aperture wavefront reconstruction. (a)–(c) Large aberration, (d)–(f) medium aberration, and (g)–(i) small aberration (The three columns correspond to the reconstructed wavefront, the original wavefront and the residuals, respectively)

Fig. 4. Multi-fringe testing verification experiment. (a) System architecture diagram; (b) experiment field diagram including beam combination (top), fiber coupler (middle) and fringe (bottom)

Fig. 5. Three-beam interference principle and its fringes in different wavelength ranges

Fig. 6. Validation results of the dual-wavelength fringe tracking. (a), (b) Interference fringes formed by the narrowband light at 1530 nm and their average cross-section; (c), (d) interference fringes formed by the narrowband light at 1560 nm and their average cross-section; (e), (f) incoherent synthesis of the dual wavelength and average cross-section

Fig. 7. Segmented mirror multipath interference fringe tracking experiment. (a) Experimental system; (b) three-path interference pattern before correction; (c) three-path interference pattern after correction