Astronomers take the temperature of the sun and stars by analyzing the spectrum of the light they emit. Now, Purdue University researchers are using light to measure temperature in tiny, nearby places, including the interior of single cells.
Researchers shoot a pulse of laser light at an object through an optical fiber. Some light bounces off and comes back up the fiber. By precisely measuring the changes to the light, it's possible to determine not only the object's temperature but its internal pressure and composition. "We're asking different questions of the same sample of light," says Dor Ben-Amotz, a physical chemist. These "molecular thermometers" could be used to gauge the quality of microcircuits on silicon or the lubricity of a micron-thin layer of oil between metal parts. Dow Chemical, 3M, and BASF are interested. Further down the line, Ben-Amotz predicts, such devices will inspect the metabolism of living cells.