Abstract
There are more than eight large aperture telescopes (larger than eight meters) equipped with adaptive optics system in the world until now. Due to the limitations such as the difficulties of increasing actuator number of deformable mirror, most of them work in the infrared waveband. A novel two-step high-resolution optical imaging approach is proposed by applying phase diversity (PD) technique to the open-loop liquid crystal adaptive optics system (LC AOS) for visible light high-resolution adaptive imaging. Considering the traditional PD is not suitable for LC AOS, the novel PD strategy is proposed which can reduce the wavefront estimating error caused by non-modulated light generated by liquid crystal spatial light modulator (LC SLM) and make the residual distortions after open-loop correction to be smaller. Moreover, the LC SLM can introduce any aberration which realizes the free selection of phase diversity. The estimating errors are greatly reduced in both simulations and experiments. The resolution of the reconstructed image is greatly improved on both subjective visual effect and the highest discernible space resolution. Such technique can be widely used in large aperture telescopes for astronomical observations such as terrestrial planets, quasars and also can be used in other applications related to wavefront correction.
Highlights
phase diversity (PD) technique was firstly proposed by Gonsalves in 1979
In the open-loop liquid crystal adaptive optics system (LC AOS), the wavefront sensor (WFS) directly measures the wavefront distortions caused by atmosphere turbulences, and the liquid crystal wavefront corrector (LC WFC) compensates for the distorted wavefront in real time
In order to eliminate the residual blur and improve the quality of image, we introduce PD technique to the open-loop LC AOS and establish a two-step high-resolution optical imaging approach
Summary
PD technique was firstly proposed by Gonsalves in 1979. After theoretical development and improvement of years, it plays a significant role in the field of adaptive optics[1, 2]. Compared to the traditional PD, the novel PD strategy can overcome the problem of non-modulated stray light It can introduce any phase aberration into the imaging branch to realize free selection of phase diversity functions. The LC AOS with PD technique is available no matter in large or small turbulences and the reconstructed images are obviously better than the focused image after open-loop correction. Such technique can be widely used in large aperture telescopes for astronomical observation such as the studies for terrestrial planets, quasars and other applications related to wavefront correction
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