PROJECT TITLE: An Ultra-Wide Intensity Range Radiometric Standard
TECHNICAL ABSTRACT (LIMIT 200 WORDS)
In this project, we will utilize the exponential dependence on voltage of the light output of a light emitting diode (LED). This characteristic will allow over 6 orders of magnitude change in intensity with better than 1% accuracy, when driven by the output of an digital-to-analog converter (DAC) of 16 bits resolution or better, such as is used in modern audio equipment. The work will emphasize experiments to precisely measure the temperature dependence of both the prefactor and exponential constant (i.e., the ideality factor) in the diode equation describing the LED's light output; to demonstrate the ability to measure the junction temperature based on the measured exponential constant of the device; and to establish the limits to the range of accurate exponential behavior. The experiments will utilize commercially available LEDs of both conventional PN junction design, and those based on heterostructures. The LED types studied will include high efficiency blue, green, and red -emitting LEDs (heterostructure devices), GaP LEDs (junction devices emitting in the red), and near-infrared LEDs.
POTENTIAL COMMERCIAL APPLICATIONS
Areas of commercial application include use of well calibrated LEDs as radiometric standards in a laboratory setting; as a built-in sensitometry calibrator for cameras used in precision photography or remote sensing; and as a built-in test source for charge coupled device -based video and still photography.
NAME AND ADDRESS OF PRINCIPAL INVESTIGATOR
Paul L. Kebabian
Aerodyne Research, Inc.
45 Manning Road
Billerica , MA 01821-3976
NAME AND ADDRESS OF OFFEROR
Aerodyne Research, Inc.
45 Manning Road
Billerica , MA 01821-3976