Physicists harness neglected properties of light

Researchers at University of Toronto successfully reveals a way to increase the resolution of microscopes and telescopes beyond their accepted limitation.

This new discovery will helps observers to differentiate very small objects that normally meld into a single blur.

We all know that telescopes and microscopes are used to observe lone subjects. Observers can detect and measure a single distant star precisely. The longer they observe, the more refined their data becomes. But this principle doesn’t applicable to all objects like binary stars.

That’s because even the best telescopes are subject to laws of physics that cause light to spread out or “diffract.” A sharp pinpoint becomes an ever-so-slightly blurry dot. If two stars are so close together that their blurs overlap, no amount of observation can separate them out. Their individual information is irrevocably lost.

More than 100 years ago, British physicist John William Strutt – better known as Lord Rayleigh – established the minimum distance between objects necessary for a telescope to pick out each individually. The “Rayleigh Criterion” has stood as an inherent limitation of the field of optics ever since.

Telescopes, though, only register light’s “intensity” or brightness. Light has other properties that now appear to allow one to circumvent the Rayleigh Criterion.

“To beat Rayleigh’s curse, you have to do something clever,” says Professor Aephraim Steinberg, a physicist at U of T’s Centre for Quantum Information and Quantum Control, and Senior Fellow in the Quantum Information Science program at the Canadian Institute for Advanced Research. He’s the lead author of a paper published today in the journal Physical Review Letters.

Some of these clever ideas were recognized with the 2014 Nobel Prize in Chemistry, notes Steinberg, but those methods all still rely on intensity only, limiting the situations in which they can be applied. “We measured another property of light called ‘phase.’ And phase gives you just as much information about sources that are very close together as it does those with large separations.”

Light travels in waves, and all waves have a phase. Phase refers to the location of a wave’s crests and troughs. Even when a pair of close-together light sources blurs into a single blob, information about their individual wave phases remains intact. You just have to know how to look for it. This realization was published by National University of Singapore researchers Mankei Tsang, Ranjith Nair, and Xiao-Ming Lu last year in Physical Review X, and Steinberg’s and three other experimental groups immediately set about devising a variety of ways to put it into practice.

Leave a Reply

Your email address will not be published. Required fields are marked *