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本文描述一种串扫热成象系统的设计和性能,着重于扫描器的设计。传感器为单元HgCdTe探测器,使用一摆镜和一截短的六面锥形镜分别作为垂直和水平扫描器。分别把扫描器的轴置于远焦系统出射光瞳的实际和水平扫描位置,从而使扫描器的尺寸最佳,符合小型化的要求。这一条件也降低了扫描平行光束的移动量,这样就为设计衍射限聚焦透镜提供了方便。利用信号处理技术补偿旋转扫描器引起的图象失真和水平扫描时间误差,已证明可以满足系统性能要求。系统的部分参数如下:视场:40×53毫弧度;角分辨率:0.4毫弧度;远焦望远镜直径:100毫米;帧频:20帧/秒;2:1隔行扫描时为121条电视线。系统性能的测试结果表明在1周/毫弧度条件下,噪声等效温差和最小可分辨温差为0.6℃,接近设计要求。
This article describes the design and performance of a tandem thermal imaging system, focusing on the design of the scanner. The sensor is a unit HgCdTe detector, which uses a pendulum and a short hexagonal mirror as vertical and horizontal scanners, respectively. The scanner's axis is placed in the actual and horizontal scanning position of the exit pupil of the afocal system, respectively, so that the size of the scanner is optimized to meet the miniaturization requirements. This condition also reduces the amount of movement of the scanning parallel beam, thus providing a convenient design for the diffraction-limited focusing lens. Using signal processing techniques to compensate for image distortion and horizontal scan time errors caused by rotating scanners has proven to meet system performance requirements. Some of the system parameters are as follows: Field of view: 40 x 53 milliradians; Angular resolution: 0.4 milliradians; telephoto telescope diameter: 100 mm; frame rate: 20 fps; 121 lines for 2: 1 interlacing . The system performance test results show that at 1 week / milliradian conditions, the noise equivalent temperature difference and the minimum temperature difference is 0.6 ℃, close to the design requirements.