基于液晶可调谐滤光片(LCTF)的多光谱面阵CCD相机是一种新型的多(高)光谱成像系统, 它利用液晶的电控双折射效应和偏振光的干涉原理, 在面阵CCD上记录任意一个波长的图像信息。 由于LCTF和帧转移型面阵CCD工作方式的特殊性, 普通的定标方法不能满足遥感应用的精度需求。 提出用积分球+标准探测器的定标系统对相机进行性能检测和定标实验, 并通过帧转移拖影校正和数据处理算法改进, 实现相机绝对辐射定标系数的计算, 最后通过外场实验对定标结果的有效性准确性进行验证。 实验结果表明, 该定标结果准确有效, 能够从获取的多光谱图像数据定量地反演出地物真实的辐射信息。 该相机辐射定标问题的解决及精度的提高, 将有效地提高其图像数据的应用领域。

Multispectral area CCD camera based on liquid crystal tunable filter (LCTF) is a new spectral imaging system, which could record image of one wavelength on the area CCD by utilizing electrically controlled birefringence of liquid-crystal and interference principle of polarized light. Because of the special working principle of LCTF and frame transfer area CCD, the existing radiometric calibration method can not meet the precision need of remote sensing application if it is used for LCTF-camera. An improved radiometric calibration method is proposed, in which the camera performance test and calibration experiment are carried out relying on the devices of integrating sphere and standard detector, and the absolute calibration coefficient is calculated via correcting frame transfer smear and improving data process algorithm. Then the validity of the laboratory calibration coefficient is checked by a field validation experiment. Experimental result indicates that the calibration coefficient is valid, and the radiation information on the ground could be accurately inverted from the calibrated image data. With the resolution of radiometric calibration of LCTF-camera and the improvement of calibration precision, the application field of the image data acquired by the camera would be extended effectively.