基于曲线拟合的红外成像测温定标方法研究

Research on Calibration Method of Infrared Imaging Temperature Measurement Based on Curve Fitting

分析了红外热像仪测温幂指数曲线拟合与三次样条插值辐射定标方法。利用高精度控温面源黑体对典型中波红外热像仪进行辐射定标,获取了黑体温度与输出电压信号的准确关系。对定标实验数据进行幂指数最小二乘拟合、三次样条插值处理,并比较了两种处理方法的测温误差,结果表明,随着定标点增加两种拟合方式获得的测温误差均逐渐下降;在整个测温范围内采用3温度点定标时,幂指数最小二乘拟合法能获得更高的测温精度;在测温范围内以温度间隔均匀分布比灰度间隔均匀分布的3定标点能获得更高的测温精度,该种定标方法的测温精度能达到0.1 K,是热像仪较为理想的一种快速准确测温定标方法。

The methods of temperature measurement power exponent curve fitting and cubic spline interpolation radiation calibration of an infrared thermal imager are analyzed.The radiation calibration of a typical middle wave(MW)infrared thermal imager is carried out by using a high accuracy temperature control surface source blackbody to obtain the correct relationship between the blackbody temperature and the output voltage signal.The power exponent the least square fitting and cubic spline interpolation are performed on the calibration experimental data,and the temperature measurement error of the two methods are compared.The result shows that the temperature measurement errors of the two fitting methods decrease gradually with increasing of fixed punctuations.The power exponent least square method can obtain higher temperature measurement accuracy when three temperature points are used in the range of temperature measurement.In the range of temperature measurement,the3-points punctuation with uniform distribution of temperature interval can obtain higher accuracy temperature measurement than that of uniform distribution of gray interval.The temperature measurement accuracy of this calibration method can reach0.1K,which is an ideal,fast and accurate temperature measurement method for thermal imager.