Research On The Effects Of Heterogeneity And The Distance To Temperature Measurement System Based On CCD

Temperature measurement system based on CCD has become a research hotspot in the field of high temperature detection in recent years, because it not only has the characteristics of low cost, fast response but also can provide the temperature field information. But the infrared thermal imager has the heterogeneity of the optical system and CCD original heterogeneity problem itself, due to material defect, light path and circuit interference factors. That leads to the output of each photosensitive element corresponding pixel gray value can’t be completely consistent. At the same time, the different distance of measuring distance and calibration of measurement error will affect the temperature accuracy of the system. These two factors should not be neglected, so the researches of solutions to these two problems are particularly important.To solve the image heterogeneity characteristic of detector, we use heterogeneity correction method based on Kang-Weiss modeling. The method is based on image segmentation and maximum matching principle.The consistency of optical vignette, natural vignette and inclination factor coefficient estimation and correction of the model by optimization, finally determine suitable for nonuniformity correction model of system. The other question is the distance change of the temperature measurement system based on CCD measurement precision influence. In this paper we use the black body furnace temperature-gray mapping curve calibration, and then through analysis of infrared radiation we get the change in the temperature measurement of distance. In the end,we summarized the distance as the variable temperature compensation model and verify the correctness of the model through the experiment.The research results indicate:Firstly, the system has made great improve uniformity after we use the method. The temperature measurement system work in a stable state, in the samples, the radiant heat image edge inside the arc, arc (top) side, side arc (bottom) temperature compensation respectively is: 50.95℃,53.08℃ and 53.08℃;Secondly, the temperature measurement range within the scope of 0.5m-4.5m, when calibration light source color temperature is 990℃,1100℃ and 1200℃ respectively, the greatest relative error of the temperature is 0.31‰,0.47%o and 0.47‰ respectively after revised. This method can effectively improve the measurement precision of the thermometer.