Dual-screen triggering system for CCD vertical target

On the request of the stable and reliable trigger required in charge-coupled device (CCD) vertical target measurement system in the condition of firing range, a dual-screen trigging system was presented . The trigging detecting screen was composed of lens-type screen detector, working with the high-intensity LED slow-scattering light, and the velocity-measuring system consists of two identical screen detectors working together with chronometer, and then it judged whether the projectile passing through the screen was real based on the measured velocity and whether to output the trigging signal or not. The time for projectile flying from impacting screen to detecting screen was achieved according to the velocity value V and the distance between impacting screen and detecting screen, and then the triggering signal was output while the projectile was approaching to CCD detecting screen. The proposed scheme can improve the stability of the system, prevent the system from being interfered by unreal targets, and can transmit trigging signal at the precise time to followup CCD image-acquisition system. It has been proved by experiment that the speed measurement error of the designed dual-screen triggering system is not more than 0.4％, fully meeting the demand of the stable and reliable trigger requirement of the CCD vertical target.