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Welcome to Oak Ridge National Laboratory's Thermographic Phosphor Sensing Applications Web Site.  Take a look at What's New in our web.


Phosphors are fine white powders which fluoresce when suitably excited. Many of them are ceramics and can withstand extremely high temperatures.  

The fluorescence characteristics change with temperature and thus a phosphor coating may indicate the temperature of the surface onto which it is coated. Seen here is a tensile specimen coated with phosphor and illuminated with a black light so that the stripes of phosphor glow red.

There are a wide variety of ceramic phosphors which fit these characteristics:

Survives hazardous chemical environments.

Not water soluble.


Easy to apply.

Tensile Specimen
The white stripes of phosphor on this metal specimen glow red when illuminated by a black light. Some phosphors have no trouble surviving and functioning in high temperatures such as those produced by this propane torch.


The basic principle of thermal phosphors is well established, and researchers at ORNL have demonstrated several useful applications [1-5].  The method relies on measuring the rate of decay of the fluorescent response of an inorganic phosphor as a function of temperature.  Having calibrated the phosphor over the temperature range of interest, a small surface deposit of phosphor is excited with a pulsed laser and the fluorescent decay is measured (typically in less than 1 msec) to calculate the temperature of the substrate.  In many instances, (e.g., in a continuous steel galvanneal process) a simple puff of powder onto the surface provides an adequate fluorescent signal.  Suitable phosphors are available to cover temperature ranges from 8 K to 1400°C [1,6-7].

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