Original Date: 11/03/1996
Revision Date: 01/18/2007

Florescence thermometry allows scientists to measure temperature in hostile environments, mobile surfaces, and inaccessible locations. Over the past decade, Oak Ridge has pioneered many developments in fluorescence thermometry. This method relies on temperature-dependent fluorescence materials called thermographic phosphors. Examples of thermographic phosphors include rare-earth-doped (activated) ceramics or compounds such as Group III metal oxides and metal oxysulfides; orthophosphates; vanadates; yttrium aluminum garnet; and fluorogermanates.

Thermographic phosphors are applied to the surface of the object by an appropriate method such as sputtering, vacuum plasma, or flame spray. Next, a laser beam, directed by optical fibers, excites the florescent properties of the thermographic phosphors. Each phosphor then generates temperature-dependent, narrow-band optical emissions which spans several hundred degrees. A light detector transmits the emissions signal back to an analyzer where a scientist calculates the temperature correlation. Since the emissions’ fluorescence lasts tens to hundreds of microseconds, both the wavelength and lifetime selection in the measurement system can adjust for extreme blackbody background light or the effects of rapidly moving surfaces.

By optimizing fluorescence thermometry, Oak Ridge offers a unique capability to its customers. Applications for measuring temperature include high-speed rotating surfaces; ambient and cryogenic liquids; on-line galvanneal steel; and internal components of turbine and combustion engines. In addition, lightweight, rugged instruments for ground, air, and space vehicles could possibly be designed and fabricated by using low-cost fibers and digital electronics to process the signals generated from fluorescence thermometry.

For more information see the Point of Contact for this survey.