Off the line-of-sight laser radar

The results of field and laboratory experiments of a novel laser radar (ladar) are presented. This ladar was designed to detect objects off the line of sight by deploying a fiber-optic relay between the launch and probe sites by monitoring the retroreflected signals. The apparatus incorporates a pulsed diode laser emitting at 1.55 mum, a wavelength that is ideal for eye safety and bears minimum loss in silica fibers. With its immediate application in transportation safety, the system issues a warning within a millisecond of detecting an obstacle in the path of a vehicle. The results of the field experiments yield signal-to-noise ratios high enough to trigger reliably an alarm with a probability of greater than 0.999 for detecting an obstacle and less than 10(-12) probability of false alarms.