Predicting Intensity Of Optical Signals Passing Through Substantial Water-Air Paths

Glen R. Allgaier

doi:10.1117/12.954498

10 November 1975 Predicting Intensity Of Optical Signals Passing Through Substantial Water-Air Paths

Glen R. Allgaier

Proceedings Volume 0064, Ocean Optics IV; (1975) https://doi.org/10.1117/12.954498
Event: 19th Annual Technical Symposium, 1975, San Diego, United States

Abstract

Experiments have been performed which measure the intensity of an optical signal which originates from a "collimated" underwater light source. A narrow beam (5°) light source was submerged at varying depths up to 16 attenuation lengths (alpha = 2.4 m-1) and pointed in a vertical direction. An optical detector was flown through the beam at altitudes to 3000 feet and pointed downward at the underwater source. The signal intensity measured through a vertical path is found to be in good agreement with the following expression: P e -kD 2 Signal Intensity = o watts/meter (at Airborne Receiver) ir(A tan 0s )2where: k = Diffuse attenuation coefficient (meters) s = Scattering coefficient (meters- 1) D = Water path length (meters) A = Air path length (meters) Po = Transmitter power (watts) Os = Half beamwidth (function of s) The data was obtained under conditions of a calm sea such that wave contributions to spreading appear negligible. Methods are discussed of predicting 0(s) from easily measured parameters.

Citation Download Citation

Glen R. Allgaier "Predicting Intensity Of Optical Signals Passing Through Substantial Water-Air Paths", Proc. SPIE 0064, Ocean Optics IV, (10 November 1975); https://doi.org/10.1117/12.954498

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