基于可控内定标源的星上红外遥感相机非均匀性校正方法

On-orbit non-uniformity correction method for infrared remote sensing systems using controllable internal calibration sources

长时间工作或环境变化时,红外焦平面阵列器件易产生非均匀性的问题。典型的星上定标方法是将系统指向深空场景或在入瞳处引入星上面源黑体辐射。覆盖全口径的星上黑体普遍体积较大、设计复杂且成本高昂。为了解决这些难题,我们提出了一种基于可控内定标装置和星空场景的红外遥感系统星上非均匀性校正方法。该方法利用可控内定标源提供不同的靶面基准辐照度,通过计算获得不同辐射定标段的定标参数,覆盖探测器动态范围,实现不遮挡视场情况下的高动态范围非均匀性校正。通过模拟指向深空场景的在轨定标过程,并对模拟图像进行非均匀性校正,用于非均匀性校正的评价图像的非均匀性由初始的15.87%下降到1.2%以下。本方法具有快速、高效、鲁棒性强等优点且具有实时处理的前景。相比于需要引入星上面源黑体的定标方法,本系统的内定标装置结构简单、设计小型化且节省成本。

Numerous detectors and the large time scale make non-uniformity correction(NUC)challenging for an infrared focal plane array.Typical calibration systems for infrared remote sensing systems block the full optical pupil and expose the sensor to an on-board calibration source(blackbody)and may also point to deep space as a calibration source.It is impractical(or expensive)to calibrate the high dynamic range remote sensing system with an on-orbit full aperture calibration source.This paper proposes and simulates an internal calibration system wherein a controllable internal calibration illumination is superimposed on the space imagery.The CICS-NUC method is applicable to the NUC when the calibration source adopts steady-state mode.After a comprehensive simulation analysis,an on-orbit NUC method based on the controllable internal calibration sources(CICS-NUC)is proposed using this type of calibrator.The proposed approach provides effective NUC without blocking the full optical pupil when the sensor stares at deep space.After executing the proposed NUC method,the non-uniformity of the evaluation image was reduced from an initial pre-correction value of 15.87%to a post-NUC value of 1.2%.The proposed approach has advantages of high efficiency,adaptability,and real-time processing.In addi⁃tion,compared with the scheme of cutting a large extended blackbody into the imaging optical path,the simple structure and compact design of the internal calibration device reduce system costs.