Abstract
To acquire images with higher accuracy of wide-field telescopes, deformable mirrors with more than 100 actuators are used, making the telescope alignment more complex and time-consuming. Furthermore, the position of the obscuration caused by the secondary mirror in the experiment system is changed with the difference of fields of view, making the response matrix of the deformable mirror different in various fields of view. To solve this problem, transfer functions corresponding to different fields of view are calculated according to the wavefront edge check and boundary conditions. In this paper, a model-based method combined with the stochastic parallel gradient descent (SPGD) algorithm is used. The experiment results show that our method can correct the aberrations with a high accuracy in both on-axis and off-axis fields, indicating that the effective actuators are well chosen corresponding to different fields of view.
Highlights
Telescopes with wide fields of view are studied to explore a wider range of space.the final image quality is determined by telescope alignment accuracy
All these methods can be classified into three categories: the direct wavefront sensor method [2,3], such as interferometers and Shack–Hartmann wavefront sensors; the wavefront sensor method based on images, such as the phase diversity method (PD) [4] and the phase retrieval method (PR) [5,6]; and the wavefront sensor-less method [7], which employs optimization algorithms such as genetic algorithm (GA) [8,9], the hill climbing method [10,11], the simulated annealing method (SA) [12], and the stochastic parallel gradient descent (SPGD) method [13,14] to correct the aberrations according to merit functions
This paper focuses on two problems of the telescope alignment
Summary
Telescopes with wide fields of view are studied to explore a wider range of space.the final image quality is determined by telescope alignment accuracy. To correct the wavefront aberrations and acquire a high-resolution image, an adaptive element such as a deformable mirror (DM) [1] is usually employed. The higher the accuracy of the optical system that is required, the more actuators of deformable mirrors that are needed. The alignment of telescopes becomes more complex and time-consuming with the increase of actuators of deformable mirrors. There are several methods used to correct the aberrations with the deformable mirror. All these methods can be classified into three categories: the direct wavefront sensor method [2,3], such as interferometers and Shack–Hartmann wavefront sensors; the wavefront sensor method based on images, such as the phase diversity method (PD) [4] and the phase retrieval method (PR) [5,6]; and the wavefront sensor-less method [7], which employs optimization algorithms such as genetic algorithm (GA) [8,9], the hill climbing method [10,11], the simulated annealing method (SA) [12], and the stochastic parallel gradient descent (SPGD) method [13,14] to correct the aberrations according to merit functions
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