Tracing of Light Rays Along a Projectile Wake
ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD
Pagination or Media Count:
The propagation of optical radiation longitudinally through the turbulent wake of a supersonic projectile is studied by means of geometrical optics. The differential equations for propagation of light rays in a non- homogeneous medium are integrated numerically for light traveling upstream from a pulsed point source located behind a moving projectile, and the shadow formed on a film located ahead of the projectile is calculated. The index of refraction is obtained from a semi-empirical model for the gas density in the wake. The calculated magnification of the projectile shadow diameter agrees with measured values to within 5 such consistency between the calculations and experimental data is taken as justification of the model. This result suggests that geometrical optics is adequate for tracing rays along a wake and, therefore, for performing design calculations in the development of an optical miss distance sensor and design systems for beam rider projectiles and missiles.
- Optical Detection and Detectors