Range gating experiments through a scattering media

This paper discusses range-gated imaging experiments performed recently at Redstone Arsenal in Huntsville, Alabama. Range gating is an imaging technique that uses a pulsed laser and gated camera to image objects at specific ranges. The technique can be used for imaging through scattering media such as dense smoke or fog. Range gating uses the fact that light travels at 3 x 10{sup 8} m/s. Knowing the speed of light the authors can calculate the time it will take the laser light to travel a known distance, then gate open a Micro Channel Plate Image Intensifier (MCPII) at the time the reflected light returns from the target. In the Redstone experiment the gate width on the MCPII was set to equal the laser pulse width ({approximately} 8 ns) for the highest signal to noise ratio. The gate allows the light reflected form the target and a small portion of the light reflected from the smoke in the vicinity of the target to be imaged. They obtained good results in light and medium smoke but the laser they were used did not have sufficient intensity to penetrate the thickest smoke. They did not diverge the laser beam to cover the entire target in order to maintain a high flux that would achieve better penetration through the smoke. They were able to image an Armored Personnel Carrier (APC) through light and medium smoke but they were not able to image the APC through heavy smoke. The experiment and results are presented