OPTICAL SYSTEM HAVING BEAM AMPLIFICATION

摘要

A laser radar system includes one or more laser amplifiers (60a) in the beam paths to provide greater optical power for increased distance. Eleven system architectures are disclosed for use with a modified Mach-Zehnder interferometer, eleven are disclosed for use with a Fizeau interferometer, and three are disclosed for use in a noncoherent optical system. The architectures are distinguished by the number and placement of the laser amplifiers in the optical paths of the system. In a coherent Mach-Zhender architecture, a laser (20) is frequency modulated with a symmetrical triangular wave by a piezoelectric transducer (PZT) controlling its non-transmitting end reflector (22). A local oscillator beam is produced by reflection at a beamsplitter (42) and is reflected (46) through a half-wave plate (48) and a beam combiner (50) to a detector (70). The direct beam from the laser (20) passes through the beam splitter (42), a Brewster angle plate (54) and a quarter-wave plate (58) to the target. A beam reflected back from the target to the Brewster plate (54) is reflected to the combiner (50) and thence to the detector (70). A laser amplifier (60a) is included between the splitter (42) and the Brewster angle plate (54).