Influence of gating and of the gate shape on the penetration capacity of range-gated active imaging in scattering environments.

Range-gated active imaging is a well-known technique used for night vision or for vision enhancement in scattering environments. A lot of papers have been published, in which the performance enhancement of range gating has been demonstrated. However, there are no studies which systematically investigate and quantify the real gain brought by range gating, in comparison with a classical imaging system, in controlled smoke densities. In this paper, a systematic investigation of the performance enhancement of range-gated viewing is presented in comparison with a color camera representing the human vision. The influence of range gating and of the gate shape is studied. We have been able to demonstrate that a short-wave infrared (SWIR) range-gated active imaging system can enhance by a factor of 6.9 the penetration depth in dense smoke. On the other hand, we have shown that the combination of a short pulse with a short integration time gives better contrasted images in dense scattering media.