Visibility Zone of Active-Pulse Vision Systems When Observing Along Inclined Paths

It is shown that four rays can be identified which determine the basic characteristic of the visibility zone for observation along an inclined path. Their origin is interpreted physically and analytic expressions for the ray lengths are obtained. Characteristic points on the observed surface are indicated which could be detected as an image on a monitor. The analytically determined distances to the characteristic points are in good agreement with experiment. Maximal use of the laser illuminator energy for viewing along an inclined path requires that the angular divergence of the illumination be consistent with the illuminator pulse duration, the strobe pulse duration, and the strobe delay time.