Optics: measuring and testing – Velocity or velocity/height measuring – With light detector
Patent
1995-09-01
1998-01-13
Buczinski, Stephen C.
Optics: measuring and testing
Velocity or velocity/height measuring
With light detector
7351426, 7386105, 2503561, G01P 336, G01P 1500, G01P 518
Patent
active
057084955
ABSTRACT:
A method and apparatus for measuring the velocity of a gas flow that does not require the seeding of the flow is disclosed. The method and apparatus produce a population of stable molecules within the flow. This population of stable molecules is produced within the flow at a first time point. A population of excited molecules is produced from the stable molecules at a second time point by exciting the stable molecules with a laser beam. This laser beam also induces fluorescence in the population of excited chemical species at the second time point. Typically, the interval between the first and second time points is known and the velocity of the flow is calculated by dividing the distance travelled by the stable molecules in the flow by the known time interval. The preferred example of the stable molecule is ozone. Oxygen molecules are fluoresced by a 193 nm laser beam at a first time point, producing oxygen atoms. Ozone is also generated in the flow with a 193 nanometer laser beam through the reaction of these oxygen atoms and molecules at the first time point. A population of excited oxygen molecules can be produced from the ozone and can be subsequently fluoresced by a 248 nanometer laser at a second time point. The velocity of the flow is determined by measuring the distance between the first and second fluorescence events and dividing this distance by the known time interval between the two time points. Since ozone is formed rapidly within the flow and is stable, both high and low speed flows can be measured using the method and apparatus of this invention.
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Brown, III Thomas M.
DeBarber Peter A.
Pitz Robert W.
Buczinski Stephen C.
Lanquist, Jr. Edward D.
Vanderbilt University
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