Preparation And Image Quality Research On High-Resolution Fiber Optic Image Inverter

High-resolution fiber optic image inverter is one of the important components in low-light level night vision device, as the output window in proximity focused image intensifier tubes, for its high coupling efficiency and low image distortion. For the resolution and signal to noise ratio of the night vision device become much higher with the development of the night vision technology from the second generation to the third generation, there will be great practice requirement and economic value to research about the image inverter with high resolution and contrast.In this dissertation, test system about the optical transfer function was set up to evaluate the image quality of image inverter and the optical transfer function measured by the test system was compared with the optical transfer function by theoretical calculation which indicate that there is still a lots of room for improvement of the image quality of image inverter. The influence factors about the contrast of image inverter were discussed and three process factors that is extra-mural absorption material, proportion of extra-mural absorption and core-cladding ratio were researched to find the optimal solution. The resolution frequency of the optimized image inverter reached 122.5 lp/mm when the value of modulation transfer function(MTF) is 0.1, which improved 37.1% to those without optimization, and had reached the same level of international product. Furthermore, the image performance at the border of image inverter was researched. The cause of regular and regional resolution degradation was explained. According to the theoretical analysis, the thickness of clad glass tube, the width of twist groove and the width of electric stove wire in twisting machine were adjusted to improve the resolution at the border of image inverter which made the failure rate decline from 45.3% to 0.2%.