Theory of ballistic trajectory measurement using a multireflective laser light screen target

A novel method of measuring flight trajectory for projectile was proposed. Seven light screen target (LST) was made up of two laser sources, two optical detectors and five pieces of mirror, which can measure the flight parameters including trajectory, direction and component velocity of three directions. The double Z-shaped LST was formed by laser light which was reflected by four pieces of parallel mirror, while the V-shaped LST was formed by laser light which was reflected by one piece of mirror. The cross points can be obtained by measuring the time when the projectile passing through every light screen. A principle experiment was done on a smooth plane table using a laser pen, four pieces of mirror and photodiode circuit by launching a steel ball. Velocity and position compare experiments were done simultaneously. The relative difference of velocity measurement was less than 0.2%. The difference of position measurement was less than 2mm. The results of velocity and position compare examination indicated the method proposed in this paper is feasible.