Accession Number : ADA189396

Title :   Development of an Optical Feedback Based High Accuracy Beam Transmissometer.

Descriptive Note : Final rept.,

Corporate Author : SEA TECH INC CORVALLIS OR

Personal Author(s) : Bartz, Robert

PDF Url : ADA189396

Report Date : 25 Nov 1987

Pagination or Media Count : 15

Abstract : The Phase I research has addressed the need for spectral light transmission data. Over the years the oceanographic community has repeatedly asked for a transmissometer operating at other wavelengths, specifically blue and green. The existing Sea Tech transmissometer is only available with a red LED, (light emitting diode) light source, mainly because LED's at shorter wavelengths have much lower power output. The primary objective of Phase I research was to determine if the transmissometer could be redesigned using LED's of other wavelengths. Constraints imposed on the new design was to achieve the same high performance inherent in the existing red transmissometer that has served the oceanic community so well for over 10 years. During the research performed in Phase I of this project a methodology and technique has been successfully developed for the stabilization of low power LED light sources to be used in the transmissometer. During the Phase I research, both red and blue LED's were evaluated in a optical bridge configuration allowing stabilization of the LED's using optical feedback. The LED's were installed in a collimator having a spatial filter 0.25 mm in diameter and a lens with a focal length of 60 mm resulting in a collimation angle of 4.16 milliradians in air. This same high degree of collimation is used in the existing Sea Tech red transmissometer.

Descriptors :   *FEEDBACK, *LIGHT TRANSMISSION, *OPTICAL PROPERTIES, *TRANSMISSOMETERS, COLLIMATORS, COMMUNITIES, CONFIGURATIONS, ELECTRIC BRIDGES, LENGTH, LIGHT EMITTING DIODES, LIGHT SOURCES, LOW POWER, OCEANS, OUTPUT, POWER, RED(COLOR), SPECTRA, STABILIZATION

Subject Categories : Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE