运动补偿下短波红外成像光谱仪的信噪比特性

The Characteristics of Spectral Radiance Measured by Imaging Spectrometer with Motion Compensation

为研究运动补偿下成像光谱仪的信噪比特性,首先推导出探测器像元采集到的光谱辐射信号与瞬时视场光轴摆角的关系式。据此,在短波红外(1.0～2.5μm)光谱范围内,计算不同摆角下系统采集到的光谱辐射信号及系统信噪比相对于观测星下点(对应光轴摆角为0°)的变化情况。结果表明:与观测星下点相比,运动补偿过程中系统采集到的总光谱辐射能量随光轴摆角的增大而减小,并且其中地面目标辐射所占的比例也随之减小。信噪比有类似的特性。要使整个观测过程信噪比提高的倍率保持或接近预期的补偿倍率,光轴摆角尽量小于30°。

In order to study the characteristics of Signal-to-Noise Ratio of imaging spectrometer with motion compensation, the relationship between measured radiance and the tilt angle of the axis of instantaneous Field Of View was derived. In the SWIR （1.0-2.5 μm）, the ratio of the spectral radiance measured by imaging spectrometer with a certain tilt angle α to that with tilt angle α=0°（correspond to observe nadir point） was calculated. Compared with observing nadir point （tilt angle α=0°）, the measured total radiance decreases along with the tilt angle the axis of instantaneous Field Of View increasing in the process of motion compensation. And the proportion of ground scene radiance in measured total radiance also becomes smaller. In order to make the increment of Signal-to-Noise Ratio to keep or approach the gain by design in the process of motion compensation, the tilt angle of axis of Instantaneous Field Of View α should be less than 30°.