Take a sneak peek at the new NIST.gov and let us know what you think!
(Please note: some content may not be complete on the beta site.).

View the beta site
NIST logo

Publication Citation: Luminous Flux Calibrations of LEDs at NIST

NIST Authors in Bold

Author(s): Carl C. Miller; Yoshihiro Ohno;
Title: Luminous Flux Calibrations of LEDs at NIST
Published: May 01, 2001
Abstract: The total luminous flux (lumen) is one of the most important characteristics of Light Emitting Diodes (LEDs), and is commonly measured using integrating sphere photometers. Large variations of measurement results are reported among different manufacturers and users of LEDs. There are issues such as the LED mounting geometry (4p, 2p), treatment of backward emission, the best integrating sphere geometries, etc. While these issues remain to be resolved, there is an urgent need for reference LEDs in order to certify measurement accuracy in industrial laboratories. To address such needs, NIST has developed measurement procedures to calibrate the total luminous flux of LEDs using the existing NIST 2.5 m integrating sphere. The arrangement for the NIST integrating sphere is for integration over 4p. In spite of the size of the sphere, the signal for typical high-intensity LEDs having total luminous flux of 0.1 lm to 1 lm is large enough for an accurate determination, in part to the high reflectance (~98 %) of the coating. The calibration service for LED total luminous flux is now available at NIST. The expanded uncertainty (k=2) of the calibration typically ranges from 0.6 % to 2.3 % depending on the color and other characteristics of the submitted reference LEDs.
Conference: CIE Expert Symposium on LED Measurement
Proceedings: Proceedings of the EIE 2nd Expert Symposium on LED Measurement
Dates: May 10-12, 2001
Keywords: calibration standard,led,total luminous flux
Research Areas: