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为减小紫外成像光谱仪中CCD暗电流噪声,提高系统信噪比,需要对CCD进行制冷.为此采用模拟比例-积分-微分电路设计了CCD制冷电路,利用Zregler-Nicholas经验整定方法确定比例-积分-微分参量,以实现降温速率不大于5℃/min、温度稳定度为±0.05℃,满足最大制冷温差.将该制冷系统应用于机载成像光谱仪进行了测试,结果表明:环境温度变化不会影响制冷效果,在达到制冷目标温度-20℃后,CCD探测器暗背景下光谱维噪声平均灰度响应值为1 072,暗背景信号非均匀性下降到0.5%,满足光谱数据反演要求.
In order to reduce the CCD dark current noise in the UV imaging spectrometer and improve the signal to noise ratio of the system, it is necessary to refrigerate the CCD.To this end, a CCD refrigeration circuit is designed by using the analog proportional-integral-differential circuit and the Zregler-Nicholas empirical tuning method is used to determine the ratio- Integral-differential parameter in order to achieve the cooling rate of not more than 5 ℃ / min, the temperature stability of ± 0.05 ℃, to meet the maximum cooling temperature differential.The cooling system is applied to airborne imaging spectrometer was tested, the results show that: the ambient temperature does not change Will affect the cooling effect. After reaching the cooling target temperature of -20 ℃, the average gray value of the spectral noise in the dark background of the CCD detector is 1 072, and the dark background signal inhomogeneity is reduced to 0.5%, which meets the requirement of spectral data inversion .