Fig. 1. Schematic diagram of PD technology with defocus as the phase diversity function

Fig. 2. Schematic diagram of cost function with single extremum (a) and multiple extremum (b)

Fig. 3. Experimental results of three different wavefront amplitudes: (from left to right) focal plane images, defocus plane images, reconstructed phases and reconstructed images

Fig. 4. Iterative direction of particle swarm optimization

Fig. 5. Phase diversity wavefront sensing based on LSTM network

Fig. 6. Phase diversity wavefront sensing based on convolution neural network

Fig. 7. First line: focal plane images; Second line: reconstructed images without denoising; Third line: reconstructed images after denoising

Fig. 8. Calibration of non-common path aberrations in NFIRAOS system with PD technology

Fig. 9. Solar observation data: (left) unreconstructed image; (right) PD reconstructed image

Fig. 10. Daytime observation of the International Space Station: (left) unreconstructed image; (right) PD reconstructed image