High-Resolution Projectile Velocity and Acceleration Measurement using Photonic Doppler Velocimetry

This paper describes the new photonic Doppler velocimetry (PDV) technique for measuring time-resolved projectile velocity and acceleration profiles. This technique is shown to provide excellent temporal and spatial resolution in measurement for full flight of the launch package launched from single- and two-stage guns. The PDV method measures the minute Doppler shift in the monochromatic light reflected from the moving surface, which is directly proportional to its velocity. The Doppler-shifted laser signal is mixed with the unshifted signal to generate a beat signal. Short-time Fourier analysis of the beat signal produces highly resolved and accurate velocity profiles. Off-the-shelf components developed for the telecommunications industry are used, producing a system that is robust and inexpensive. Other examples of PDV measurements are provided in a companion paper on impact response of glass bars.