Apparatus for enhancing visibility in fog or underwater

摘要

Apparatus for illuminating and enhancing the visibility of a region in a transparent medium containing light scattering particles, such as fog or smoke in air or particles in water, comprises a source of a beam of illumination that is narrow in one plane and a viewing collimator for narrowly restricting the observer's instantaneous field of view in a single plane having the same general vertical, horizontal or other orientation as the beam of illumination. The viewing collimator and the illuminating source are spaced apart and mounted for relative movement of the collimated instantaneous field of view and the illuminating beam to cause them to intersect in a region in front of and distant from the observer and for the region of their intersection to scan a larger region. This effectively reduces the amount and effect of light scatter from illuminated particles in the foreground which would otherwise tend to dazzle the observer or otherwise obscure distant objects; the observer is thus enabled to see, or to see more clearly, into the illuminated region.