Modelling the Point Spread Function of Wide Field Small Aperture Telescopes With Deep Neural Networks -- Applications in Point Spread Function Estimation

The point spread function (PSF) reflects states of a telescope and plays an important role in development of smart data processing methods. However, for wide field small aperture telescopes (WFSATs), estimating PSF in any position of the whole field of view (FoV) is hard, because aberrations induced by the optical system are quite complex and the signal to noise ratio of star images is often too low for PSF estimation. In this paper, we further develop our deep neural network (DNN) based PSF modelling method and show its applications in PSF estimation. During the telescope alignment and testing stage, our method collects system calibration data through modification of optical elements within engineering tolerances (tilting and decentering). Then we use these data to train a DNN. After training, the DNN can estimate PSF in any field of view from several discretely sampled star images. We use both simulated and experimental data to test performance of our method. The results show that our method could successfully reconstruct PSFs of WFSATs of any states and in any positions of the FoV. Its results are significantly more precise than results obtained by the compared classic method - Inverse Distance Weight (IDW) interpolation. Our method provides foundations for developing of smart data processing methods for WFSATs in the future.