Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers developed highly accurate method for measuring luminous efficacy of LEDs

21.09.2015

The method helps discovering the most efficient lamps, which may save billions in lighting costs in the future

Researchers at Aalto University and VTT Technical Research Centre of Finland have succeeded in developing a method which helps to improve the relative uncertainty in measuring the luminous efficacy of LEDs from the approximate five percent of today to one per cent in the future. The results were just published in the distinguished Light: Science & Applications journal.


PQED consists of a Brewster window (left) protecting the detector elements from impurities, adjustable bellows and the detector chamber itself. In order to further decrease uncertainties in measurement, the window was removed and the detector was protected from impurities using nitrogen flow.

Credit: Aalto University

Thus far, solutions based on incandescent lamps have been used in photometry, i.e. in measuring light detected by the human eye, explains Tomi Pulli, a doctoral student at Aalto University.

- The photometers that lamp manufacturers use for calibrating their devices have been produced and calibrated for incandescent lamps, which results in errors when measuring the efficacy of LEDs. In our research, we used a LED lamp with a well-defined spectrum and a PQED detector, which we developed together with VTT MIKES Metrology and European partners, and whose spectral responsivity can be determined highly accurately. Therefore, there was no need for the problematic optical filters used in applications based on incandescent lamps. Indeed, accurately determining and analysing the spectrum of the LED was the most challenging and crucial part of the research, he reveals.

... more about:
»LEDs »VTT »efficacy »lamps

From a dot to a sphere

The detector used in measurements by Pulli and his co-researchers measures the illuminance of LEDs in a very small area. According to Professor Erkki Ikonen, the head of research, the next step will be to move onto measurements corresponding to real-life conditions for lighting.

LED lamps emit light to all directions. In order to measure the luminous efficacy, we thus use a device called an integrated sphere, which takes into account light coming from different directions, he specifies and reminds us that the history of LEDs is still short when compared to incandescent and fluorescent lamps. Therefore, there is still little information available on their actual efficacy and ageing properties. Indeed, it is essential to determine luminous efficacy as accurately as possible so that such lamps can be introduced in the market that transform as much electrical energy into light useful to the human eye as possible.

- So far, the portion of LEDs has been merely around ten per cent globally, but the amount is increasing at a rapid pace, Ikonen explains.

- Lighting amounts to approximately 20 per cent of the electricity consumption in the world. Once the share of LEDs increases close to 50 per cent, an improvement of as little as one percent in the accuracy of measuring the luminous efficacy of the lamps introduced in the market will mean saving billions of euros each year.

###

More information:

Doctoral Student Tomi Pulli
Aalto University, School of Electrical Engineering
tel. +358 50 408 2782
tomi.pulli@aalto.fi

Professor Erkki Ikonen
Aalto University, School of Electrical Engineering
tel. +358 50 550 2283
erkki.ikonen@aalto.fi

Article http://www.nature.com/lsa/journal/v4/n9/full/lsa2015105a.html

Media Contact

Tomi Pulli
tomi.pulli@aalto.fi
358-504-082-782

 @aaltouniversity

http://www.aalto.fi/en/ 

Tomi Pulli | EurekAlert!

Further reports about: LEDs VTT efficacy lamps

More articles from Power and Electrical Engineering:

nachricht A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes
20.07.2018 | Science China Press

nachricht Future electronic components to be printed like newspapers
20.07.2018 | Purdue University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>