Test method for halo disappearance time of low-light-level image intensifier

The halo effect has a negative impact on the application of detection of low-light-level image intensifier, and it is unavoidable. The method for testing the halo disappearing time of optical image intensifiers is lacking. To address this, a halo disappearing time test system based on digital vision was proposed. The system provides a pulse signal with a frequency of 25 Hz and an adjustable duty cycle to the LED light source through a switching power supply. A high frame rate camera captures 1 500 images of the image intensifier passing through a small hole with a diameter of 3.5 mm, including several complete light and dark cycles. To obtain accurate results, the period information is optimized by repeatedly calculating the standard deviation to remove the periodic sequence that deviates from the average value. This process allows us to identify the index of the picture where the light source is turned off in the bright and dark period. Similarly, the number of pictures where the halo disappears can be obtained, thereby calculating the disappearance time of the halo. The image multiplier halo disappearance time is 3.33ms with the serial number GZ318118A. The test results show that the repeatability of the measuring device is 0.863%, which can effectively test the disappearance time of the halo.