US 5,293,046 AGranted

Optical high pressure sensor

AssigneeThe United States of America as represented by the Secretary of the Air Force

InventorSamuel E. Wheatley

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Abstract

A high pressure sensor which uses a ruby as a pressure sensor is disclosed. This system includes a high pressure Hg lamp which is used to excite the ruby R1 and R2 lines because it has a spectrum which is a good match to the ruby absorption spectrum. The Hg lamp output is filtered to pass wavelengths shorter than about 6300 angstroms so as not to affect the detection system. The light is directed through a dichroic mirror which passes all of the lamp output. The lamp output is then coupled into the optical fiber and carried to the test point. A small ruby is cemented to the end of the fiber and the whole crystal is aluminized. Some of the fluorescence will couple into the fiber and be carried back to the dichroic mirror which reflects ruby fluorescence into the detector but passes any of the original lamp light. The aluminum coating on the ruby increases the amount of fluorescence that is collected. In this configuration, the ruby serves as an optically dynamic pressure sensor, since the fluorescence of the ruby produces known spectral wavelength shifts in response to pressure changes in its environment.

An optical pressure sensor comprising:

an excitation source which produces an illumination signal;
an optical sensor which receives said illumination signal from said excitation source, said optical sensor responding to said illumination signal with fluorescence which experiences a spectral wavelength shift in response to its environment, said wavelength shift in said fluorescence providing an optical measurement in pressure changes which are ambient to said optical sensor;
a means for measuring said spectral wavelength shift in said fluorescence produced by said optical sensor, said measuring means thereby yielding an indication of pressure changes in said optical sensors environment, said pressure changes ranging up to about 10 kbars said measuring means also receiving a temperature measurement signal and adjusting said indication of pressure changes for changes in temperature;
a means for conducting optical signals;
said optical conducting means optically connecting said optical sensor with said excitation source and said measuring means, said optical conduction means thereby conducting said illumination signal to said optical sensor, and conducting said fluorescence from said optical sensor, to said measuring means;
and
a means for measuring temperatures in proximity with said optical sensor and outputing said temperature measurement signal so that thermally induced changes in said wavelength shift of said fluorescence are anticipated and subtracted from the wavelength shift actually measured, said temperature measuring means thereby providing an opportunity to eliminate thermal contamination from the indication of pressure changes measured in said optical sensor's environment;
and
a means for recording data, said recording means being electrically connected with said means for measuring said spectral wavelengths shift and said means for measuring temperature so that an actual wavelength shift of said fluorescence is measured while effects of thermal contamination of said wavelength shift are accounted for and eliminated from the induction of pressure changes in said optical sensor's environment.

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Abstract

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