电子倍增电荷耦合器件(EMCCD)利用电荷雪崩机制可以实现低于1e-的读出噪声, 适用于微光成像。随着背照式CMOS成像探测器技术的发展, 具有高量子效率和低于1.5e-读出噪声的CMOS成像探测器已中国科学院长春光学精密机械与物理研究所研制成功。针对天基微光成像的需求, 分别构建了基于EMCCD CCD201的天基微光相机和基于CMOS的天基微光相机, 并建立了系统的噪声模型。对基于EMCCD的天基微光相机和基于CMOS的天基微光相机的微光探测性能和工作机理进行了对比分析。分析结果表明: 当采用凝视成像模式, 积分时间为2 s, 相机入瞳辐亮度为10-9 W·cm-2·sr-1·μm-1时, 基于EMCCD的天基微光相机在焦面温度为20 ℃的条件下的信噪比为23.78, 相同条件下基于CMOS的天基微光相机的信噪比为27.42。当采用制冷系统将焦面温度降低至-20 ℃时, 基于EMCCD的天基微光相机的信噪比提高到27.533, 而基于CMOS的天基微光相机的信噪比提高到27.79。

Electron Multiplying Charge Coupled Device(EMCCD) can realize read out noise of less than 1e- by promoting gain of charges with the charge multiplication principle and is suitable for low light imaging. With the development of back illuminated CMOS technology CMOS with high quantum efficiency and less than 1.5e- read noise has been developed by Changchun Institute of Optics, Fine Mechanics and Physics(CIOMP). Spaceborne low light detection cameras based on EMCCD CCD201 and based on CMOS were respectively established and system noise models were founded. Low light detection performance as well as principle of spaceborne camera based on EMCCD and spaceborne camera based on CMOS were compared and analyzed. Results of analysis indicate that signal to noise(SNR) of spaceborne low light detection camera based on EMCCD will be 23.78 as radiance at entrance pupil of the camera is as low as 10-9 W·cm-2·sr-1·μm-1 at the focal plane temperature of 20 ℃. Spaceborne low light detection camera worked in starring mode and the integration time is 2 s. SNR of low light detection camera based on CMOS will be 27.42 under the same conditions. If cooling systems are used and the temperature is lowered from 20 ℃ to -20 ℃, SNR of low light detection camera based on EMCCD will be improved to 27.533 while SNR of low light detection camera based on CMOS will be improved to 27.79.