Abstract: An active imaging retroreflection based optical system for the detection of other optical systems, especially passive optics used for observation/surveillance, or targeting. The active imaging system is switchable from either near-IR laser illumination, to a combination of near-IR and visible laser light illumination. The illumination is shaped into narrow elongated beams, generally elliptical in shape. These beams are channeled by rhomboid prisms so as to be emitted collimated to each other and monostatic to the detection system, such that the retroreflected return image returns axially to the optical detection system. The return image is resolved and refined by a series of objective and field lenses, and by a dual band, visible light and near-IR, pass filter, to add clarity and contrast.

Abstract: A system for detection of optical type devices being used by an enemy sniper subject without alerting the enemy is shown. A coherent laser beam of a wave length in the visible color range, is sent along an axis and passing through a beam splitter device. A detection means is arranged to generate a signal when it detects retro-reflections from the target optical devices or subject including clutter reflections in a 180 degree direction relative to axis. The detection means is coaxially mounted with the source of illumination with a second detection means off axis therefrom to generate a second detection signal when it detects clutter reflections from the target optical devices or subject. A comparator means forms a difference signal between the retro-reflected detection signal and the second detection signal and indicates when the difference signal exceeds a predetermined threshold.