Depth thermography goes beyond the surface

The approach from a team at the University of Wisconsin-Madison may be useful in applications where traditional temperature probes will not work, like monitoring semiconductor performance or next-generation nuclear reactors.

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Many temperature sensors measure thermal radiation, most of which is in the infrared spectrum, coming off the surface of an object. The hotter the object, the more radiation it emits, which is the basis for devices like thermal imaging cameras.

According to UW-Madison, depth thermography goes beyond the surface and works with a certain class of materials that are partially transparent to infrared radiation.

"We can measure the spectrum of thermal radiation emitted from the object and use a sophisticated algorithm to infer the temperature not just on the surface, but also underneath the surface, tens to hundreds of microns in," said Mikhail Kats, a UW-Madison professor of electrical and computer engineering. "We're able to do that precisely and accurately, at least in some instances."