Performance Calibration of the Wavefront Sensor's EMCCD Detector for the Cool Planets Imaging Coronagraph Aboard CSST

TL;DR

This paper presents a comprehensive calibration and characterization of an EMCCD detector used in the wavefront sensor of the Chinese Space Station Telescope's coronagraph, ensuring high performance for exoplanet imaging.

Contribution

It introduces a multi-stage screening protocol and analyzes the EMCCD's gain and noise properties to optimize detector performance for space-based astronomical observations.

Findings

High resolution and low noise achieved in the selected EMCCD

Optimal EM Gain range identified for signal amplification

Detector meets initial application requirements for CPI-C

Abstract

The wavefront sensor (WFS), equipped with an electron-multiplying charge-coupled device (EMCCD) detector, is a critical component of the Cool Planets Imaging Coronagraph (CPI-C) on the Chinese Space Station Telescope (CSST). Precise calibration of the WFS's EMCCD detector is essential to meet the stringent requirements for high-contrast exoplanet imaging. This study comprehensively characterizes key performance parameters of the detector to ensure its suitability for astronomical observations. Through a multi-stage screening protocol, we identified an EMCCD chip exhibiting high resolution and low noise. The electron-multiplying gain (EM Gain) of the EMCCD was analyzed to determine its impact on signal amplification and noise characteristics, identifying the optimal operational range. Additionally, noise properties such as readout noise were investigated. Experimental results demonstrate that the optimized detector meets CPI-C's initial application requirements, achieving high resolution and low noise. This study provides theoretical and experimental foundations for the use of EMCCD-based WFS in adaptive optics and astronomical observations, ensuring their reliability for advanced space-based imaging applications