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24-26 September 2008, Rome, Italytemperature of such MCPCB mounted power LEDs stabilizesin the order of magnitude of 60s when attached to acold-plate. (This can be verfied by thermal transient measurements.)III. CONCLUSIONSFig. 3. The block diagram of the auto calibrator kit for thecalibration of integrating sphereThe thermal management in the solid-state-lighting is acrucial question. The calculation of the junction temperaturehas to be more precise to fulfill the lifetime estimations andto maintain the reliability of the LEDs used in many applications.For accurate thermal and optical measurements of highpower LEDs it is inevitably required to execute an accuratecalibration of the photometer sphere, which is responsiblefor every further characterization and calculation. Fromthese reasons the spectral responsivity of the usedphotodetector and the spectral reflectance of the inner coatingof the integrating sphere have to be known and the standardLEDs used for the calibration have to match closely thespectral distribution of the test LEDs. In the introduced autocalibratorsystem all of these criteria are fulfilled and calculatedin an automated way, furthermore the equipment enablescomfortable and high accuracy measurements to bedone within much shorter time, than generally.REFERENCES[1] G Farkas, Q van Voorst Vader, A Poppe, Gy Bognár:"Thermal Investigation of High Power Optical Devicesby Transient Testing",IEEE T COMPON PACK T 28:(1)45-50 (2005)Fig. 4. Fast calibrator kit with multiple colored standard LEDs for the calibrationof integrating sphereIn the calibration process the LEDs are turned on and off oneby one controlled by the software of the measurement system.The software stores all the measured parameters neededfor the further calculation and for thermal and optical characterization.All the measurements can be executed if the LEDis in thermal steady state and the current flowing through theLED is constant. The thermal steady state of the LEDs is assuredby a thermoelectric cooler (Peltier) and the constantcurrent-supply is provided by a high accuracy current source.The calibration kit and the calibration procedure allowsusers to purchase integrating spheres precalibrated withoutinvestment in any costly standard LEDs. The purchase becomespossible also for those thermal labs, where the radiometric/opticalproperties of the measured LED have to beknown.[2] G Farkas, S Haque, F Wall, P S Martin, A Poppe, Q vanVoorst Vader, Gy Bognár:"Electric and Thermal TransientEffects in High Power Optical Devices", In: Proceedingsof the 20th IEEE Semiconductor ThermalMeasurement and Management Symposium (SEMI-THERM'04). San Jose, United States Of America,2004.03.09-2004.03.11.(20) 2004. pp. 168-176.[3] G Farkas, Q van Vorst Vader, A Poppe, GyBognár:"Thermal Investigation of High Power OpticalDevices by Transient Testing",In: Proceedings of the 9thInternational Workshop on THERMal INvestigations ofICs and Systems (THERMINIC'03). Aix-en-Provence,France, 2003.09.24-2003.09.26.pp. 213-218.[4] Comission Internationale de l’Éclairage, Measurement ofLEDs, Publication CIE127.2 (Revision of CIE127-1997)Draft No. 4, Dec. 2003.[5] www.micred.com/teraled.html[6] Csuti P, Kránicz B, Schanda J. Comparison of the goodnessof fit of photometers to the V(λ) function using realLED spectra. CIE LED Symposium, Tokyo 2004.[7] E.Fred Schubert: Light Emitting Diodes, ISBN 13 978-0-521-86538-8, Cambridge University Press, 2006[8] CIE 1984a, Determination of the Spectral Responsivity ofOptical Radiation Detectors, 1984[9] CIE 2004. Colorimetry, 2004[10] CIE 1989, Measurement of Luminous Flux, 1989[11] CIE x029:2006, Determination of Measurement Uncertaintiesin Photometry, 2006©EDA Publishing/THERMINIC 2008 92ISBN: 978-2-35500-008-9