Accession Number:

AD0711307

Title:

ON THE MUTUAL COHERENCE FUNCTION OF AN OPTICAL WAVE IN A TURBULENT ATMOSPHERE

Descriptive Note:

Corporate Author:

RAND CORP SANTA MONICA CA

Personal Author(s):

• Lutomirski, R. F.
• Yura, H. T.

Report Date:

1970-07-01

Pagination or Media Count:

26.0

Abstract:

Part of an overall study of phenomena that affect the performance of optical or infrared reconnaissance and guidance equipment, the present work shows that the most commonly used expression for the mutual coherence function for an optical wave propagating in a turbulent atmosphere is, in general, incorrect. This expression is based on an unphysical extrapolation of the Kolomogorov spectrum. In modifying the spectrum, however, the corrections to the coherence function, the implied resolution, spreading of a finite beam, and the signal-to-noise ratio using heterodyne detection, can be considerable. Approximate expressions for the coherence function, valid over three distinct propagation distance regimes, are derived. The field is shown to have a greater transverse coherence length than that predicted by other researchers, the difference being more pronounced at shorter ranges. Thus, under many conditions, the performance degradation of devices that depend on the above properties is less than previously reported.

Descriptors:

• *INFRARED EQUIPMENT
• *LIGHT TRANSMISSION
• ATMOSPHERIC MOTION
• BESSEL FUNCTIONS
• COHERENT RADIATION
• INFRARED DETECTORS
• LASERS
• MATHEMATICAL ANALYSIS
• PERFORMANCE(ENGINEERING)
• RANGE FINDING
• RESOLUTION

Subject Categories:

• Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE