Redefining brightness: a new way to measure light

Posted on Wednesday, April 3, 2019

Electric light bulb in the dark


That 100-Watt light bulb you just bought for your living room lamp might never be the same again, thanks to researchers at the University of Ottawa. Samuel Lemieux and his colleagues are working on a better, cheaper and more reliable way to measure the intensity of light, and their discovery could result in a new standard to measure its brightness.

One application of this discovery could lead to a superior classification of light bulbs, which is interesting, but quite mundane. In the scientific world and in labs across the globe, however, it could mean so much more.

We calibrate scales and make sure the whole world is on one system of measurement thanks to the International System of Units, which defines seven units of measure as a basic set from which all other SI units (SI for “Système international”) can be derived.

On May 20, 2019, the world’s top scientists will change one of those units: the kilogram. The 129 year-old standard, a platinum-iridium alloy cylinder named “Le Grand K”, will be replaced. The kilogram will now be attached to the Planck constant, a fundamental and universal concept in quantum mechanics that is immutable.

Lemieux and his team at uOttawa are proposing to do the same thing, but with the way we measure light. In his research, Lemieux has found a new source of light whose brightness depends only on the laws of physics. This source of light could be used as a new and universal standard for the intensity of light, without the need for a reference source or detector.

 “Our research demonstrates what could become a new standard for the brightness of light,” explained Lemieux. “The process that produces light is initiated by quantum noise within a nonlinear crystal and amplified in such a way that we can extract the total number of photons. This could have profound implications on the level of precision and accuracy of current methods in radiometry.”

This discovery could have a deep impact on the way we define and test the scientific units for the intensity of light and radiation. It could help the scientific community ensure that the whole world is on the same system of measurement, and it also has the potential to be implemented in many laboratories, since it requires very modest infrastructures, unlike the other standards for radiometry. 

The research paper was published in Nature Physics.


For media inquiries:
Orian Labrèche
Media Relations Officer
Cell.: 613-863-7221

Back to top