High-precision velocity measuring system for projectiles based on retroreflective laser screen

The flying velocity of projectile is a key parameter for evaluating weapon performances. Here we adopt retroreflective laser screen optoelectronic approach to realize real-time, non-contact, reproducible, high-precision measurement for projectile velocity. Two fan-shaped laser screens combining with retroreflective films construct the sensing area, the changed luminous flux while the projectile flying through the screens is converted by optoelectronic detect module, collected with high-speed data collecting module, saved and processed by software. We study the retroreflective light spots by imaging when a one-dimensional expanding line-shaped laser beam incidents the cone cube reflective sheeting and the glass microsphere retroreflective material respectively. Based on the study result, an off-axis inclined spherical reflector with a central laser-penetrating hole, combining with a line-shaped LD and a large area PD, is used to achieve the laser screen transmitting-receiving integration optoelectronic detection. For the purpose of high precision, we propose a maximum negative slope algorithm finding the optimal timing feature points to calculate the velocity. The self-comparison experimental data with 7.62 mm projectile indicate that the measuring precision by this method can reach 0.19‰.