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Realization of a Laboratory Tuneable Colour  Light Source L&E 28 (1) 2020

Light & Engineering 28 (1)

Volume 28
Date of publication 02/20/2020
Pages 90–98

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Realization of a Laboratory Tuneable Colour Light Source L&E 28 (1) 2020
Articles authors:
Nina Carli, Armin Sperling, Grega Bizjak

Nina Carli, M. Sc., studied at the Faculty of Electrical Engineering, University of Ljubljana in Slovenia. She graduated in Electrical Engineering with her diploma thesis about Spectrum Optimization of the Tuneable Colour Light Sources. She gathered the academic experience during an internship at PTB in Germany, and in Laboratory of lighting and photometry at the Faculty of Electrical Engineering in Ljubljana, Slovenia

Armin Sperling, Ph.D. He received his doctoral degree from the TU Braunschweig in 1994. In 2001, after six years being in research and development in industry, he joined the PTB and currently heads the Photometry and Spectroradiometry Department. He is associate Director of the CIE Division 2, Chairman of the German National Committee of the CIE and member of the DIN advisory board of the standardization committee for Light

Grega Bizjak, Ph.D., Professor. At present, he is a Head of Laboratory of Lighting and Photometry at Faculty of Electrical Engineering, University of Ljubljana. He is active in the field of lighting and photometry as well as in the field of electrical power engineering. His main research interests in lighting are photometry, energy efficient indoor and outdoor lighting, use of daylight and use of LEDs in lighting applications. Prof. Bizjak is the President of Slovenian National Committee of CIE and representative of Slovenia in CIE Division 2

A spectrally tuneable colour light source (TCLS) has been designed and constructed at Physikalisch-Technische Bundesanstalt (PTB), Germany. It consists of an integrating sphere with 24 LEDs which are driven by a computer-controlled power supply. It is intended for producing any visible spectral distribution and to mimic various light sources for use in laboratories as a calibration source. With the help of an integrated spectrometer, a closed loop operation was introduced to improve the performance of the TCLS and to spectrally stabilize its output spectrum. Before practical realization of the TCLS a series of simulations have been made to predict its performance and capability with a number of different target spectrums. During the practical implementation we have encountered difficulties, namely optimization of the output spectrum, dependency of LED spectra on the electric current through the LED and temperature of the LED, non-linearity of LED’s luminous flux with respect to electric current through the LED and some difficulties with small synthesis coefficient values, which were all successfully solved.
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