Abstract: A beam of light issued by a light source enters a catadioptric arrangement and initially travels therethrough along an axis. At least one lens is situated at the axis and is axially delimited by two curved major surfaces having respective centers of curvature. The beam of light is reflectively diverted from the axis and travels in a path which includes a path section that is directed at one of the major surfaces and has such a spatial orientation relative to the axis and the major surfaces that light traveling in this path section bypasses the centers of curvature and impinges all regions of the major surfaces at angle deviating from respective normals to the regions with attendant avoidance of specular retroreflection from such regions.

Abstract: An optical radar operating in the infrared region of the spectrum and adad to efficiently detect elongated targets such as wires. The pulsed transmitter is preferably passively Q-switched and produces optical pulses polarized in one direction. A CW local oscillator laser is locked to a frequency slightly offset from the transmitter frequency. A Brewster angle duplexer and a quarter wave plate in the transmit/receive path of the radar permit the transmitter flux to pass to a scanner and direct the orthogonally polarized echo signals to the heterodyne receiver which includes a display or alarm circuit. The transmitter and local oscillator lasers include frequency control circuits. Either wedge or ball joint type scanners may be used to scan the radar beam over a target area of interest.