Study On Calibration Technology For Low-light-level Image Intensifier Calibration Device Of Signal To Noise Ratio

The low-light-level image intensifier is the core part of the night vision device, and the signal to noise ratio (SNR) which affects the performance of LLL instruments directly is the important performance indicators of LLL image intensifiers. In order to solve the question of LLL image intensifier SNR test, SNR test device is developed and calibration technology of calibration device is studied.The LLL image intensifier SNR test principle, condition and method are introduced first. According to the testing requirement, LLL image intensifier SNR calibration device is designed and produced, including general structure, uniform diffuse weak source system, conjugated symmetry lens system, test shield, photoelectricity test system, SNR calibration software, and control computer, etc, so the automatic measurement is realized. Furthermore, because the source diameter is 0.2mm, and its illuninance is 1.08×10-4 lx or 1.29×10-5 lx which cannot be measured directly, the photon counting measuring technology of tiny spot illuninance is studied, and then tiny spot illuninance calibration system is developed. A new method that PMT pulse identity technology calibrates tiny source illuninance is used, so the tiny source luminometer can be demarcated correctly and the source illuninance of LLL image intensifier SNR test device can be measured directly. Then, the calibration method and trace approach of the LLL image intensifier SNR test are developed, and the calibration experiment is carried out. The result shows that SNR can be calibrated correctly by this method, so a feasible calibration method for SNR value unification is proposed. At last, many types LLL image intensifiers, super Ⅱ generation XX2540 and XX2040 and Ⅲ generation 18/18 etc, are calibrated on this device, and experiment data are obtained. Main factors which affect the measurement results are analyzed, and the uncertainty is estimated.