Velocity Measurement Using Single Optical Detector and Two Reflectors

Velocity measurement for projectile usually used more than two optical targets. A novel measurement method by using three light screens target which was made up of one light source, one optical detector and two reflectors was proposed in this paper. The parallel beams of light source were reflected twice to optical detector, which formed three light screens. The light source was discussed, the measurement principle was analyzed. The typical signal output in four cases was discussed and a single channel chronometer based on DSP TMS320F2812 was designed for the method. The time resolution of the chronometer is 10 ns and the maximum error is less than 90 ns. A compare experiment was done by using laser pen, photodiode circuit, chronometer, reflector and a steel ball on a smooth plane table. The relative difference of velocity measurement was less than 0.2%, which indicates that the method is feasible.