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Proceedings Paper

Novel approach for LED luminous intensity measurement
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Paper Abstract

Light emitting diodes (LEDs) are being utilized as the light source in increasingly complex and sophisticated products, including flat panel displays, surgical lamps and even digital projectors. These applications place extreme demands on LED performance, which, for both the developer and manufacturer, translate into the need to precisely characterize and control source output, specifically color and luminous intensity distribution characteristics. Unfortunately, the traditional methods for performing luminous intensity and colorimetric measurements of LEDs suffer from several significant drawbacks. In particular, spot photometers and radiometers only sample a very limited amount of source output and operate very slowly. The latter factor can be an important consideration, even in research settings, because LED output is often not stable over time, especially during warm-up or in the presence of temperature or input power fluctuations. Thus, a long data acquisition period can make an instrument report spatial output variations that don't really exist. Now, new instrumentation based on the Imaging Sphere enables rapid, high spatial resolution measurement of LED color and luminous intensity over an entire hemisphere. This paper reviews the parameters typically utilized to characterize LEDs, explores Imaging Sphere operation, and compares the results of Imaging Sphere measurements with highly accurate reference data from a goniophotometer.

Paper Details

Date Published: 25 February 2008
PDF: 12 pages
Proc. SPIE 6910, Light-Emitting Diodes: Research, Manufacturing, and Applications XII, 69100C (25 February 2008); doi: 10.1117/12.760817
Show Author Affiliations
Ron Rykowski, Radiant Imaging, Inc. (United States)
Hubert Kostal, Radiant Imaging, Inc. (United States)

Published in SPIE Proceedings Vol. 6910:
Light-Emitting Diodes: Research, Manufacturing, and Applications XII
Klaus P. Streubel; Heonsu Jeon, Editor(s)

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