Researchers Detail a Theoretical "Cloak of Invisibility" for Thermal Sensors
The theoretical cloak can modify the thermal signature of or entirely hide an object — and could potentially do the same for visible light.
An international team of scientists have proposed a theoretical invisibility cloak, of sorts, which serves to either change the appearance of or entirely hide an object from view — providing, that is, you're looking only at its heat emissions through a thermal camera.
"We present an active cloaking method for the parabolic heat (and mass or light diffusion) equation that can hide both objects and sources," the scientists explain in the abstract to their paper. "By active we mean that it relies on designing monopole and dipole heat source distributions on the boundary of the region to be cloaked. The same technique can be used to make a source or an object look like a different one to an observer outside the cloaked region, from the perspective of thermal measurements."
In short: They believe they have developed a cloak of invisibility for the thermal signature of objects. Based around heat pumps, the team believes it can modify the appearance of a given object — or make it disappear from the view of a thermal camera altogether. "So at least from the perspective of thermal measurements," Fernando Guevara Vasquez explains, "they can make an apple appear as an orange."
While having an object disappear from a thermal camera's view is neat - and of potential interest to militaries and spy agencies worldwide - the team believes the work has broader applications: The cloak could be used to prevent heat-generating components from interfering with heat-sensitive ones nearby, and may have use for improving drug delivery - and could theoretically, one day be adapted to hide an object visibly as well as thermally.
There are, of course, caveats: The research is currently theoretical, assumes a "probing" point source of heat which can be bent around the object being detected, which is not the approach used by most thermal cameras, and requires prior knowledge of the object to be cloaked - but the approach is, "in most cases," the same regardless of the type of object.
A pre-print version of the paper is available under open access terms on arXiv.org.