Absolute photometry has relative benefits for LED and SSL performance evaluation

Aug. 15, 2008
Photometric testing methods are changing in response to the increased adoption of solid-state lighting, explains Ian Lewin.
The lighting industry is buzzing with excitement: solid-state lighting (SSL) is being celebrated as the solution to many of today’s energy and lighting application challenges. Available lumens per watt (otherwise known as the efficacy) of commercial white LEDs now far exceeds that of incandescent sources. In the laboratory, LEDs have been developed with efficacies similar to f luorescent and certain highintensity discharge (HID) sources.

However, we do not yet know to what extent such devices will become viable in the future as a replacement for existing high efficiency sources; issues such as manufacturability, cost and temperature stability must be addressed. Until these issues are sufficiently answered within the lighting industry, replacement costs and procedures will remain a reasonable concern to commercial purchasers.

Even if today’s SSL performance results are as good as the industry ever produces, a wide range of applications can be satisfied already. With performance increases actually coming at a surprising pace, and with anticipated reductions in manufacturing costs, LEDs certainly appear to be a major light source of the future.


This article was published in the July/August 2008 issue of LEDs Magazine.

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