Research On Infrared Camera Large Dynamic Range Testing Technology

In recent years,infrared thermal imaging system is widely used in military and civil fields.Thermal imaging with large dynamic range adaptable to intense radiation interference has become an important development direction at home and abroad.The technical parameters of infrared camera directly affect the application performance of infrared thermal imaging system,and the dynamic range is an important criterion to evaluate the performance of infrared camera.The difference between the large dynamic range testing technology and the traditional testing technology is that the radiation source with wide temperature range is adopted,the hardware device has great influence on the radiation energy transmission,and the testing efficiency is low.This thesis mainly aims at the testing requirements of infrared camera with large dynamic range.A new test method is proposed,a spatial distribution model of test equipment is established,and the influence of blackbody uniformity and stability on test results is studied.On this basis,a high precision and high efficiency large dynamic range testing system is redesigned and built,and satisfactory testing results are obtained.Firstly,according to the principle of infrared camera temperature measurement,the energy signal conversion model is established.From the mathematical model,the factors affecting temperature measurement are deeply analyzed.At the same time,the noise of the infrared camera is analyzed and classified,and the main noise sources affecting the temperature measurement accuracy are analyzed.It is concluded that the photon shot noise obeys poisson distribution in time domain and space domain.Secondly,the test error tree was established based on the test principle,and the main error sources of the test system were analyzed.Aiming at the problems such as low efficiency of time domain noise testing in the test of large dynamic range,and the stability of domestic black body could not meet the requirements,a test method combining photon transfer curve and frame subtraction was proposed.Two frames of images can be used to calculate the noise at each temperature measurement point,which not only ensures the testing accuracy but also improves the testing efficiency and saves the memory space.Thirdly,in order to ensure the uniformity,stability and accuracy of the radiation provided by the testing device to the focal plane of the infrared camera to be tested,the spatial distribution relationship model of each component of the testing device were established according to classical geometrical optics and radiation transfer theory.The quantitative constraint relation of relative position and aperture of each component is obtained,which provides theoretical basis for the establishment of hardware architecture of the system.Fourth,using the photon transfer curve combined with frame subtraction method to measure the results of the noise,containing the blackbody poor uniformity influence on test.According to the uniformity distribution function of blackbody,a mathematical model was established,and the simulation analysis was carried out to quantify the error of the influence of uniformity of blackbody.Further improved the test accuracy.Fifth,based on the spatial distribution model of the test device and optimization methods,the software and hardware design of the test system,the construction of the hardware platform and the writing of the software program are completed.Finally,experiments were carried out to prove that the accuracy and efficiency of the test system were improved by 3.217% and 12.2% compared with the traditional method,which proves the correctness and feasibility of the model and method established in this thesis.