초록 ▼

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 reflect

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. For heterodyne operation a selected frequency difference is generated whereas for homodyne detection a zero frequency difference is generated. An electronic computer coordinates the position of the scanning laser of the transmitter and the position of the local oscillator beams of the receiver such that one of the local oscillator beams will overlap with each of the corresponding return signals at the detector array. A second electronic computer processes the output of the detector array to provide information about the return signal.

대표청구항 ▼

A coherent optical receiver for receiving a coherent return signal comprising: a variable reflectance surface; means for generating a linearly polarized coherent signal; directing means for directing said coherent signal to unformly illuminate said variable reflectance surface; steering means for in

A coherent optical receiver for receiving a coherent return signal comprising: a variable reflectance surface; means for generating a linearly polarized coherent signal; directing means for directing said coherent signal to unformly illuminate said variable reflectance surface; steering means for increasing the reflectance of said variable reflectance surface in a plurality of selected small areas to reflect said coherent signal that is incident on each of said selected small areas in a diffracted pattern having a conical shape, said steering means simultaneously increasing the reflectance in each of said selected small areas; collimating means for receiving and collimating the reflected portion of said coherent signal reflected from each of said selected small areas to form a plurality of local oscillator beams at the output of said collimating means; a summation means for summing said coherent return signal with the plurality of said local oscillator beams wherein said steering means selectively directs one of said local oscillator beams to overlap said return signal; and detecting means for receiving the output of said summing means and providing a detected output signal in response to one of said local oscillator beams overlapping said return signal.