Research On Key Technologies And Algorithms Of Temperature Measurement System Of Uncooled Infrared Thermal Imaging

Infrared temperature measurement technology has many merits such as the wide temperature range, not changing the temperature field distribution of the measured object and remote non-contact temperature measurement and so on, but the complexity of this sophisticated technology delays its development process and the range of applications. There are still quite a number of difficult issues that are not fully resolved, and the accurate measurement of the true temperature of the target surface is even more difficult. This paper does a lot of research in the realization of the temperature measurement of the uncooled infrared thermal imaging and the accuracy of temperature measurement, especially spend a great deal of effort in terms of improving the accuracy of infrared temperature measurement.This paper combines the thermal radiation theory and the internal structure of infrared cameras and establishes a physical model of infrared temperature measurement and obtains the equations of the infrared radiation thermometry, then discuss the temperature equation. The analysis of the relevant factors which affect the uncooled infrared thermal imager gets the relative error formula caused by surface emissivity, environment temperature, atmospheric transmittance and atmospheric temperature. Then focus on the analysis of the influence of the surface emissivity of the object to the temperature measurement accuracy and propose four methods for measuring the surface emissivity of the object to meet the measurement needs of the surface emissivity in a variety of applications.Through previous analysis, design and implement hardware and software systems of infrared camera temperature and build experimental platform of infrared temperature measurement. Discuss the mechanism of the non-uniformity of uncooled infrared focal plane arrays and obtain non-uniformity correction algorithm that adapts to temperature measurement implementation. Design and implement the radiometric calibration method, and get the fitting formula of the output voltage of infrared camera and the reference temperature blackbody source, then combine with temperature measurement equation to calculate the surface temperature of the measured object.According to the relevant test results, analyze the reasons of uncooled infrared camera temperature drift and specifically test the influence of ambient temperature, power fluctuation and the changes of the absorption of infrared radiation on the output voltage of uncooled infrared focal plane arrays. Put forward two methods to reduce the temperature drift of the infrared thermal imager, the hardware circuit is improved: use the good thermal stability, low power consumption and high precision components, and use the high accuracy, low dropout voltage and low drift integrated voltage stabilizing elements to regulate power supply, otherwise add high-accuracy TEC temperature control circuit; two is software compensation, focus on the analysis of the influence of environmental temperature changes on the plane array output voltage, and then study compensation algorithm, so obtain a compensation algorithm of reducing the temperature drift. When the ambient temperature is 35oC and the actual temperature of the measured target is 60oC, the measurement temperature before compensation is 75.538oC and deviates from the actual temperature 15.538oC, and its measurement error reaches 25.897%. Through this method, the measurement temperature is 60.332oC and the measurement error is 0.553%, so this method improves the accuracy of temperature measurement.