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热成象系统性能取决于最小可分辨温差(MRTD)表达式中含有的一大类参数,利用系统执行程序和设计程序确定具体的解析关系。本文计算由设计程序和技术条件限制下,当视场和探测器张角固定不变时,热成象系统性能与探测器面积和光学孔径的尺寸及形状的依赖关系。叙述了三种冷屏蔽型(理想型、矩型和无冷屏蔽)的分析模型,并用以推导MRTD表达式。矩型冷屏蔽表达式明显的显示出基本参数的依赖关系,这和使用普遍接受的冷屏蔽效率参数形成鲜明的对照。此外,叙述和利用了串扰的分析模型。业已证明,忽略串扰,也就是不考虑利用可能制作的最小面积的冷屏蔽型探测器,系统将得到最好性能,而考虑串扰最小时,是否可采用较小面积的探测器要权衡串扰对MRTD衰减情况而定。对于受衍射限制的光学系统,考虑到各种冷屏蔽类型,计算了矩形和圆形光学系统的光学孔径尺寸对MR-TD的影响。就不同限制下的最佳的光学子系统,利用最低的MRTD标准得出结论。业已证明,使用接近衍射限值的孔径时,矩形光学系统能大大改进MRTD的高频特性。
The performance of a thermal imaging system depends on a large set of parameters contained in the expression of the minimum resolvable temperature difference (MRTD), using the system executive and design procedures to determine the specific analytical relationship. In this paper, the dependence of the thermal imaging system’s performance on the size and shape of the detector area and the optical aperture when the field of view and the detector’s angular aperture are fixed by the design procedure and the technical conditions is calculated. Three types of cold-shielded (ideal, rectangular, and cold-free) analytical models are described and used to derive MRTD expressions. The rectangular cold shield expression clearly shows the dependence of the basic parameters, in sharp contrast to the commonly accepted cold shield efficiency parameters. In addition, a crosstalk analysis model is described and used. It has been shown that by neglecting crosstalk, that is, without considering the possibility of making a cold-shielded detector of the smallest possible area, the system will achieve the best performance, while considering the smallest crosstalk, the possibility of using smaller-area detectors weighs crosstalk against MRTD Depends on the circumstances. For diffraction limited optical systems, considering the various types of cold shields, the effect of the optical aperture size of the rectangular and circular optical systems on MR-TD is calculated. The best optical subsystems for different constraints use the lowest MRTD standard to conclude. Rectangular optical systems have been shown to greatly improve the high frequency properties of MRTD when using apertures close to the diffraction limit.