空基红外载荷现场辐射定标技术研究

Research on Field Radiometric Calibration of Aerial Infrared Loads

为解决外场条件下空基红外载荷对典型地物目标进行辐射温度测量时,现场辐射定标存在地面定标黑体发射率低、远近场辐射特性差异大、定标体不能适应不同成像分辨率载荷定标和外场布设及撤收不便捷等问题,研制了地面温差型定标黑体,具有高发射率、均匀性和稳定性等特点,制作了高发射率定标板和低发射率定标板.提出了基于双温度扩展源法实现红外载荷绝对辐射温度定标,利用高发射率定标板和低发射率定标板通过远、近地场的图像灰度变换实现相对辐射定标的方法.为了验证方法的有效性,以高精度辐射温度计在近地场对典型地物目标测量的辐射温度数据作为依据,对本方法和现有的基于大尺寸面源黑体实现现场辐射定标的方法进行了比较,并开展了测量不确定度的评定.结果表明,本方法辐射温度定标最大偏差 0.31℃,测量不确定度评定结果为 0.46℃(k=2),定标精度较好.同时定标板具有尺寸可定制、布设及撤收灵活、成本低等特点,可适用于对不同成像分辨率空基红外载荷的现场辐射定标,进而为目标隐身效能评估、红外仿真建模、目标特性研究等工作提供一定的技术支持.

In order to solve the problems of low emissivity of the ground calibration blackbody,large differences in radiation characteristics between the far and near fields,the inability of the calibration body to adapt to the calibration of loads with different imaging resolutions,and the inconvenience of setting up and withdrawing from the field when the space-based infrared load carries out radiant temperature measurements of typical geographic targets under the conditions of the outfield,a high emissivity calibration plate and a low emissivity calibration plate are developed.A ground temperature difference type calibration blackbody with high emissivity,uniformity and stability is developed,and high emissivity calibration plates and low emissivity calibration plates are made.A method is proposed to realize the absolute radiation temperature calibration of infrared load based on the double temperature expansion source method,and the relative radiation calibration is realized by the image gray scale transformation of far and near ground field using the high emissivity calibration plate and the low emissivity calibration plate.In order to verify the validity of the method,the radiant temperature data measured by a high-precision radiation thermometer on a typical feature target in the near-field are used as the basis for comparing the present method with the existing method based on a large-size surface-source blackbody for realizing in-situ radiant calibration,and the evaluation of the measurement uncertainty is carried out.The results show that the maximum deviation of the radiant temperature calibration of this method is 0.31℃,and the measurement uncertainty evaluation result is 0.46℃(k=2),which is a good calibration accuracy.Meanwhile,the calibration plate has the features of customizable size,flexible deployment and withdrawal,low cost,etc.It can be applied to the on-site radiometric calibration of space-based infrared loads with different imaging resolutions,which can provide certain technical support for the assessment of target stealth effectiveness,infrared simulation modeling,target characterization and other work.