中、长波热红外系统辐射测温精度比较

Comparison of radiation temperature measurement precision between middlewave and longwave thermal-imaging systems

对测量用热红外系统在3～5μm和8～12μm波段的辐射测温精度进行比较分析,研究是在典型的实验室条件下进行的,并且以温度范围为270～900 K的目标作为研究对象。首先推导出了红外系统的抗干扰函数DRF,根据DRF曲线可以看出,相同大小的信号干扰对中波红外系统的温度测量精度影响要小一些。然后针对目标的物理特性和实验环境对测温精度的影响进行理论分析,基于理论公式,分析了干扰信号(发射率估计误差、大气透过率、目标反射辐射和光学系统辐射变化)对测温精度的影响。从分析结果看出,在典型的温度范围内,中波红外系统的测温精度比长波红外系统的精度高。

A comparison study on temperature measurement precision between middlewave 3 5 μm and longwave 8 12 μm measuring thermal imaging systems has been conducted. The study is limited to indoor condition and the target＇ s temperature is within the range of 270 900 K. Firstly, the Disturb Resisting Function （DRF）of infrared systems is deduced. From the DRF curve,we find that the middlewave infrared system suffers smaller impact than the longwave system under the same degree of disturbance. It has been developed a theory about the influence of target＇s physical characteristic and measurement conditions on the accuracy of temperature measurement. On the basis of the developed formulas, it has been made an analysis of the influence of signal disturbances（ because of incorrectly assumed emissivi ty, limited transmittance of the atmosphere, radiation reflected by the object and shift of optics radiation）on the accu racy of temperature measurement. It has been found that the middlewave systems in typical temperature range offer better accuracy than the longwave systems do.