Wavefront sensorless adaptive optics system for extended objects based on linear phase diversity technique

Abstract Wavefront sensorless (WFSless) adaptive optics (AO) systems have been widely studied in recent years. However, most of the existing WFSless AO systems require point sources for wavefront sensing. Aimed to correct the turbulence-degraded imaging of extended objects, this document proposes a fast wavefront correction approach for a WFSless AO system based on linear phase diversity (PD) technique. By linearizing the system optical transfer function (OTF) and expanding the influence functions of the deformable mirror (DM) on Zernike basis, this method can establish a linear relationship model between the drive voltages of the DM and the CCD acquired extended images. Then the control signal of the DM can be directly output to generate a compensated wavefront from CCD images and fast adaptive wavefront correction can be realized. Numerical simulations and an experimental validation are performed under different turbulence strengths, the results show that the proposed method has an impressive improvement of root mean square (RMS) of wavefront and can effectively restore the turbulence-degraded extended images with a relatively fast correction speed.