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Proceedings Paper

The Measurement Of Optical Coherence Loss In Atlantic Waters
Author(s): William J. Stachnik
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Paper Abstract

This paper describes optical coherence loss and very small angle forward scatter mea-surements performed in Atlantic coastal waters. The technique used to measure coherence loss involved the use of an argon-ion laser source and a self-aligning interferometer capable of projecting two confocal beams to ranges of approximately 10 and 20 meters. The interference patterns formed at the common focal point of these beams were used to determine the normalized degree of coherence at spatial frequencies ranging from 10,000 to 100,000 cycles/radian. The measurement of very small angle forward scatter was also accomplished using the argon laser source. However, instead of using two apertures to produce two interfering beams, a single 50 mm aperture was used. The results of these measurements for Florida waters show that coherent optical behavior is present at all spatial frequencies measured. The response (i.e., the value of the normalized degree of coherence) tends to fall at the higher spatial frequencies, but often this behavior is dominated by significant temporal variations. Very small angle forward scattering experiments (1-300 microradians) have provided some insight into these temporal variations. These measurements show in-water beam diameters varying between 3 and 10 times their diffraction limited spot diameters within relatively short time intervals. Also observed in these experiments was a granulation (spatial spiking) of the beam at very small angles. This granulation possesses a scale size approximately equal to that of the diffraction limited spot size of the 50 mm source aperture used in this test. The optical parameters of the water, its T-S microstructure, and other oceanographic parameters were also recorded.

Paper Details

Date Published: 10 November 1978
PDF: 12 pages
Proc. SPIE 0160, Ocean Optics V, (10 November 1978); doi: 10.1117/12.956861
Show Author Affiliations
William J. Stachnik, Naval Underwater Systems Center (United States)

Published in SPIE Proceedings Vol. 0160:
Ocean Optics V
Matthew B. White; Robert Stevenson, Editor(s)

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