Free Surface Velocity Measurement of an Impacted Projectile by Optical Doppler Shift

Publisher Website
Google Scholar
Abstract
An optical technique for measuring the velocity of an accelerating, specularly reflecting surface from a position on the axis of motion has been successfully applied to a free surface velocity measurement of an impacted projectile in a pneumatic accelerator. The technique combines a laser light source, a surface tilt‐insensitive, lensless optical configuration, and a Fabry‐Perot spectrometer to obtain a velocity‐time profile of the impacted projectile. The technique involves unique features in addition to surface tilt insensitivity. These include a mode matching scheme which permits the use of high power, multilongitudinal mode lasers where formerly a single frequency laser was required. Experimental results are presented and compared with independent accelerometer measurements.