姿态倾斜对时-空联合调制型干涉成像光谱仪成像质量的影响

时空联合调制型干涉成像光谱仪获取的像面干涉图是带有干涉条纹的二维空间图像,具有对姿态变化敏感的特点.根据该类仪器的成像过程,在竖直摄影时,相邻两帧像面干涉图之间的像移量为一列像元;偏离竖直摄影时,由于像面干涉图的几何变形或旋转,会引入非正常像移.利用共线方程导出了这一非正常像移量的表达式.利用仿真计算说明:这一非正常像移会在像面干涉图序列中不断积累,导致提取出的物体干涉信息失真.在竖直摄影而平台指向精度较低、倾斜摄影、探测器阵列的安装方向精度较低或者航空成像且存在偏流角时,必须对像面干涉图进行有效校正,才能保证最终反演出的物体光谱的真实性.

Effect of Oblique Attitude on Image Quality of Spatio-Temporally Modulated Imaging Fourier Transform Spectrometers

The spatio-temporally modulated imaging Fourier transform spectrometers obtain two-dimensional spatial images modulated by interference pattern, and are sensitive to the change of attitude. According to the imaging principle of these instruments, image motion between two interference images should be one column of pixels when the instruments are in a vertical attitude, and abnormal image motion would arise because of geometric distortion and rotation of the interference images when an attitude incline exists. The expression of the abnormal image motion was deduced from the collinear equation. It was proved by numeric simulation that the abnormal image motion would accumulate in the interference image series and would make the objects′ interference pattern distorted. The interference images should be corrected to ensure the reality of the restored spectra in one of the following cases: vertical photography with platform of low pointing accuracy, oblique photography, low orientation accuracy of detector array, and aerial photography with a drift angle.