Mock Observations for the CSST Mission: End-to-End Performance Modeling of Optical System

TL;DR

This paper develops an end-to-end simulation model for the CSST optical system, quantifying image degradation sources and optimizing wavefront distribution to enhance image quality in space telescopes.

Contribution

It introduces a comprehensive integrated system model with error sub-models and demonstrates how wavefront optimization can improve PSF ellipticity across the FOV.

Findings

Average REE80 of 0.114 arcseconds at 25 field points

Correlation between wavefront errors and PSF ellipticity

Wavefront optimization can improve image quality

Abstract

This study presents a comprehensive end-to-end simulation analysis of the optical imaging performance of the China Survey Space Telescope (CSST) under in-orbit conditions. An integrated system model incorporating five static and two dynamic error sub-models was established. Wavefront errors were calculated for each sub-model and compared to the integrated system error to quantify the individual contributions to image degradation. At the detector level, wavefront error, point spread function (PSF), and ellipticity were evaluated across the full field of view (FOV). The average radius of 80\% encircled energy (REE80) of the PSF under full-error conditions was determined for 25 field points, yielding a value of 0.114 arcseconds. Furthermore, the calculations indicate a correlation between the wavefront distribution and the ellipticity distribution within the optical system. By optimizing the wavefront distribution, it is possible to adjust the ellipticity distribution of the PSF across the full FOV. The end-to-end simulation approach adopted in this paper provides a theoretical foundation for improving the image quality in large-aperture, off-axis space telescopes.