Engineers at the University of Wisconsin, Madison are able to perform remote temperature measurements in 3D objects. What they have discovered is a way to determine the temperature beneath the surface of certain materials using a new technique called depth thermography. This method may be helpful in places where traditional measurement techniques don’t work, such as monitoring semiconductor performance and next-generation nuclear reactors.
There are a vast number of sensors that can measure thermal radiation. For the most part, this is done in the infrared spectrum and radiates off the surface of the object. The process is simple, the hotter an object gets the more it emits radiation. This is the basis for devices we are all familiar with, like thermal imaging cameras. Depth thermography is a bit different, going beyond the surface and working with certain materials. Those materials are somewhat transparent to infrared radiation.
Using sophisticated algorithms researchers were able to measure the spectrum of thermal radiation emitted from the object. This process goes one step further and can infer temperature levels below the surface of the material, not just on the surface. The research allowed the measurement underneath the surface from tens to hundreds of microns deep.
The team for this project heated a sample of fused silica (a particular type of glass) and measured the properties including temperature with a spectrometer. At this point, working backward from the results of temperature readings at various depths of the samples, using computational tools they had previously developed. These tools could read the temperature at different depths based on the thermal radiation given off by objects composed of multiple materials. Working backward, they used the algorithm to determine the temperature that best fit the experimental results.
In this part of the research, they achieved a proof of concept. In the future, the team hopes to apply this technique to more complex multilayered materials. Then they will apply a machine learning algorithm, to the technique which will improve the process. Eventually, depth thermography can be used for such delicate operations as determining the different operating temperature distributions that a semiconductor might have as it operates.
There could be a place in modern temperature profiling for this type of 3D modeling. It could be used to map clouds of high-temperature gasses and liquids. Such liquids could include molten salt in molten-salt reactors, where determining temperature fluctuations in the salt are needed throughout the volume of a substance. This can now be done without temperature probes that might not be able to withstand temperatures of 700°C.
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A study by the University of Wisconsin | Depth Thermography
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