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Real-time method and apparatus for measuring the decay-time constant of a fluorescing phosphor

United States Patent

September 7, 1999
View the Complete Patent at the US Patent & Trademark Office
A method for determining the decay-time constant of a fluorescing phosphor is provided, together with an apparatus for performing the method. The apparatus includes a photodetector for detecting light emitted by a phosphor irradiated with an excitation pulse and for converting the detected light into an electrical signal. The apparatus further includes a differentiator for differentiating the electrical signal and a zero-crossing discrimination circuit that outputs a pulse signal having a pulse width corresponding to the time period between the start of the excitation pulse and the time when the differentiated electrical signal reaches zero. The width of the output pulse signal is proportional to the decay-time constant of the phosphor.
Britton, Jr.; Charles L. (Alcoa, TN), Beshears; David L. (Knoxville, TN), Simpson; Marc L. (Knoxville, TN), Cates; Michael R. (Oak Ridge, TN), Allison; Steve W. (Knoxville, TN)
American Iron and Steel Institute (Washington, DC)
08/ 966,657
November 10, 1997
NOTICE OF GOVERNMENT INTEREST The Government of the United States of America has rights in this invention pursuant to Cooperative Agreement No. DE-FC07-93ID13205 awarded by the U.S. Department of Energy.