Accession Number:

AD0837611

Title:

COHERENT OPTICAL ADAPTIVE TECHNIQUES.

Descriptive Note:

Final rept. 1 Mar 67-1 Mar 68,

Corporate Author:

AUTONETICS ANAHEIM CA

Personal Author(s):

• Cathey, Wade T.
• Hayes, Cecil L.
• Davis, Walter C.

Report Date:

1968-07-01

Pagination or Media Count:

34.0

Abstract:

A system was designed, constructed and tested which provides dynamic adaptive phase compensation for atmospheric distortions. This demonstrates that arrays can be built larger than previously thought possible because of atmospheric effects. Without adaptive controls, the atmosphere limits the signal-to-noise ratio improvement and the beamwidth reduction which can be obtained using a larger transmit-receive aperture. We accomplished phase compensation for the transmitted beams and the received signals of a two-element 10.6 micron array. By providing adaptive phase control to assure that the two transmitted beams arrived at the target in phase, the power on target was increased by at least 75 percent over the nonadapted case. In addition, the amplitude fluctuations of the received signals were drastically reduced because the adaptive transmitting system eliminated the frequent destructive interference normally seen when two beams are transmitted. Adaptive control of the relative phase of the two received signals before adding also resulted in comparable increases in signal power. The locking of two lasers with a 4.5 MHz difference frequency provided the local oscillator for heterodyne detection. A near target 500 feet and a far target 3 miles from the transmitter were used. Author

Descriptors:

• *COHERENT RADIATION
• *INFRARED LASERS
• *OPTICAL RADAR
• LIGHT TRANSMISSION
• FEASIBILITY STUDIES
• PHASE MODULATION
• PHASE SHIFT CIRCUITS
• ADAPTIVE SYSTEMS
• CORRECTIONS
• DISTORTION
• PHASE LOCKED SYSTEMS
• INTERFERENCE
• PHASED ARRAYS
• INFRARED RADIATION
• GAS LASERS

Subject Categories:

• Lasers and Masers
• Optical Detection and Detectors

Distribution Statement:

APPROVED FOR PUBLIC RELEASE