声光可调谐滤波器(AOTF)成像光谱仪是一种新型高光谱成像系统。 针对系统存在的波段间辐射灵敏度差异较大, 低照度条件下部分波段信噪较低的问题, 引入了电子倍增CCD(EMCCD)作为感光器件。 对该原理仪器在普通和电子倍增两种工作模式下的噪声进行了分析, 推导了信噪比模型, 并利用研制的原理样机进行了实验验证。 在此基础上, 提出了电子倍增模式下系统动态范围的评价方法, 给出了以入瞳光谱辐亮度为判据的工作模式选择方法。 结果表明, 信噪比模型与实测结果吻合, 电子倍增模式的合理选择有效提高了低照度条件下的信噪比, 改善波段间辐射灵敏度的非一致性。

Imaging spectrometer based on acousto-optic tunable filter (AOTF) is a novel hyperspectral imaging system. In order to rectify the non-uniformity of radiation sensitivity on different waveband, especially the low signal-to-noise (SNR) in low-light conditions, the electron-multiplying CCD (EMCCD) sensor was proposed. The noise of AOTF imaging spectrometer was analyzed in both normal and EM modes of the CCD sensor with derived SNR calculating model which has been experimentally validated. On that basis, a new evaluation method of the dynamic range in EM mode and a novel method of calculating spectral radiance at the entrance aperture were adopted. The experimental result shows that the theoretic SNR models are fit, and better selection of EM mode is effective to improve the SNR and non-uniformity of radiation sensitivity in low light level conditions.