| With the rapid development of infrared remote sensing technology,infrared measurement equipment has been widely used in the fields of satellite earth observation,military strategic deployment,auxiliary meteorological observation,and monitoring and prevention of disasters.With the continuous development of technology and the increasing demand for the application level of infrared remote sensing information quantification,the calibration accuracy of infrared measurement equipment has been increasingly demanded.The large-diameter surface blackbody source has gradually become the focus of research and application due to its advantages of large radiation aperture,small size,light weight,convenient full-field calibration and suitable for onboard applications.The surface blackbody source can be divided into two types without microcavity structure and microcavity structure according to the structural form: the radiation characteristics of the surface blackbody without microcavity structure mainly depend on the intrinsic emissivity of the high emissivity coating material.With the passage of time,it is easily affected by environmental pollution and the attenuation of the coating performance;the surface blackbody source with microcavity structure adds the blackbody cavity effect on the basis of the high emissivity coating on the surface,which can better guarantee the radiation characteristics.Long-term stability,more suitable for long-term application of space environment.However,through experiments we found that the black body source with microcavity surface will cause obvious temperature nonuniformity due to its structural characteristics,working temperature,heating method,working environment and conditions,etc.,which will not only affect its radiation characteristics evaluation results,when When it performs radiation calibration for standardized equipment,it will inevitably have a far-reaching impact on the accuracy of infrared radiation measurement and the quantitative application of remote sensing information.In response to the above questions,in order to answer the influence of factors such as the design parameters of the microcavity structure,the operating temperature and the heating method on the temperature non-uniformity,the magnitude and law of the influence of this temperature non-uniformity on the radiation characteristics of the black body,and the consideration of the temperature non-uniformity Whether the radiation characteristic evaluation model can be improved and perfected later,the thesis takes Vgroove micro-cavity structure black body source as an example,through physical experiment,simulation analysis,theoretical modeling and other means,mainly carried out the following research work:(1)Combined with the developed V-shaped black body source,after designing a platinum resistance temperature measurement scheme and verifying its temperature measurement accuracy using standard methods,the temperature control accuracy and temperature stability of the black body radiation source were tested and verified.Then the infrared thermal imager and platinum resistance after the standard chamber black body calibration were used to test the radial and axial temperature uniformity of the black body source.It was found that the temperature non-uniformity of the black body source mainly comes from the axial direction.The related experimental test results also provide the basis of experimental parameters for the subsequent simulation analysis of the radiation characteristics.(2)Aiming at the axial temperature non-uniformity,the temperature distribution model of trapezoidal groove ribs for V-shaped black body source is established.Based on the theory of heat transfer,the temperature distribution of non-isothermal microcavity structure is studied by changing the structural parameters of the surface black body source Law;established a mathematical model to simulate the law of the infrared hemisphere emissivity of the coating material with temperature;combined with the law of the coating material with the temperature of the microcavity,improved and proposed a V shape that can consider the influence of temperature non-uniformity on the radiation characteristics Evaluation model and calculation method of effective emissivity of black body source with groove structure.(3)Based on the proposed radiation characteristic evaluation model,according to the physical experiment test results,by reasonably setting the temperature difference gradient,the magnitude and effect of the influence on the radiation characteristics of the V-groove surface blackbody source are considered and not considering the temperature nonuniformity A comprehensive comparative analysis of the laws was carried out,and the relevant recommendations for the design of the surface blackbody source structure were given and the following conclusions were drawn: the radial temperature nonuniformity is better than 0.1K,which has little effect on the effective emissivity;It is larger and is the main influencing factor that affects the accuracy of the evaluation of radiation characteristics;The effect of effective emissivity is only of the order of 10-4～10-3,and the effect is not large;but when the temperature unevenness reaches 10 K,the effect on the effective emissivity can reach 0.01 ～ 0.02,Influential;in order to control the influence of axial temperature non-uniformity on radiation characteristics,it is necessary to optimize structural design parameters,limit working temperature,use more advanced heat transfer materials and heating methods,and ensure a reasonable working environment and conditions In order to ensure the accuracy of the evaluation results of the radiation characteristics of the surface black body source,and further guarantee the infrared radiation measurement accuracy and the quantitative application ability and level of remote sensing information. |
PDF Full Text Request