Improving the Capture-range Problem in Phase-diversity Phase Retrieval for Laser-wavefront Measurement Using Geometrical-optics Initial Estimates

To overcome the capture-range problem in phase-diversity phase retrieval (PDPR), a geometrical -optics initial-estimate method is proposed to avoid a local minimum and to improve the accuracy of laser-wavefront measurement. We calculate the low-order aberrations through the geometrical-optics model, which is based on the two spot images in the propagation path of the laser, and provide it as a starting guess for the PDPR algorithm. Simulations show that this improves the accuracy of wavefront recovery by 62.17% compared to other initial values, and the iteration time with our method is reduced by 28.96%. That is, this approach can solve the capture-range problem.