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. The energy is further enhanced by being amplified by a highly sensitive detector, such as a third generation imager; or a high sensitivity, back-illuminated CCD (charge coupled device); or a high sensitivity wide dynamic range CMOS (complimentary metal-oxide semiconductor) sensor. The retroreflected energy, processed by this third generation imager, or the like, appears as a concentrated point of light, or bright spot, that can be quickly and easily distinguished from its surroundings, which also appear to the user.