Australian scientists said they've developed the world's most accurate and sensitive thermometer, one that uses light and can gauge temperature to a precision of 30 billionths of a degree.
Researchers at the University's of Adelaide's Institute for Photonics and Advanced Sensing say in addition to its accuracy it's fast as well, measuring temperature in less than one second.
"We believe this is the best measurement ever made of temperature -- at room temperature," says research leader Andre Luiten, head of the Experimental Physics at the institute.
The thermometer sends two light beams -- one green, one red --into a disk of crystalline material, through which they move at slightly varying speeds because of their different wavelengths.
That difference is dependent on the temperature of the disk, the researchers say.
"When we heat up the crystal we find that the red light slows down by a tiny amount with respect to the green light," says Luiten, who is also the chair of the university's School of Chemistry and Physics.
Because the difference is miniscule to the point of almost being immeasurable, the system spins the beams around the circumference of the disk many thousands of times, each trip increasing the difference by a tiny amount until it can be precisely measured.
The phenomenon is similar to the way sound can reinforce itself and be concentrated in a curved space, such as the famous "whispering gallery" in St. Paul's Cathedral in London that allows whispers on one side of the chamber to be clearly heard on the other.
The reinforcement of the difference in the speeds of the two wavelengths is what finally makes the precise measurement of temperature possible, the researchers say.
"To emphasize how precise this is, when we examine the temperature of an object we find that it is always fluctuating," Luiten says. "We all knew that if you looked closely enough you find that all the atoms in any material are always jiggling about, but we actually see this unceasing fluctuation with our thermometer, showing that the microscopic world is always in motion."
The prototype system could lead to instruments capable of making very precise measurements of other quantities such as force, pressure, humidity or the identification of particular chemicals, the researchers said in an article on their work published in the journal Physical Review Letters.
Such precision measurements of different quantities in the environment using instruments small enough to be portable could revolutionize technologies used in many fields, including industry and medicine, the researchers said.
