Scanning laser radar
In an optical radar system a coherent signal is transmitted at a variable position and the return signal, that is, the reflected portion of the coherent signal is received and coherently detected. The transmitter utilizes a scanning laser having an electron beam that impinges upon a variable reflectance mirror that terminates one end of an optical cavity. An oscillating mode is generated within the resonant cavity when the electron beam locally heats the surface of the variable reflectance mirror to create a pixel that reflects light in a diffracted pattern. The receiver utilizes a stable single mode laser to illuminate a variable reflectance surface. A receiver electron beam generates a plurality of receiver pixels at various positions. The diffracted light from each pixel generates a plurality of variable angle local oscillator beams that are summed with the return signal at a beamsplitter. The output of the beamsplitter is applied to the surface of a detector array. One of the local oscillator beams is positioned such that the return signal and the local oscillator beam overlap at one of the detectors in the array to provide coherent detection. The frequency of the first coherent signal and the second coherent signal are sampled by a first and second partially reflecting mirror. A frequency detector detects the output of the first and second partially reflecting mirror to detect the frequency difference between the first and second coherent signal and generate a control signal that adjusts the frequency of the first coherent signal.
- Assignee:
- LTV Aerospace and Defense Company
- Patent Number(s):
- US 4515471
- OSTI ID:
- 6401404
- Resource Relation:
- Patent File Date: Filed date 25 Aug 1981; Other Information: PAT-APPL-296074
- Country of Publication:
- United States
- Language:
- English
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