Arbitrary spectral matching using multi-LED lighting systems

Aleix Llenas; Josep Carreras

doi:10.1117/1.OE.58.3.035105

29 March 2019 Arbitrary spectral matching using multi-LED lighting systems

Aleix Llenas, Josep Carreras

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Optical Engineering, Vol. 58, Issue 3, 035105 (March 2019). https://doi.org/10.1117/1.OE.58.3.035105

Abstract

Spectrally tunable light sources for general lighting have recently attracted much attention as versatile solutions that can be used in humancentric lighting implementations provided with excellent color rendering and increased user perception. However, temperature and age-dependent color shifts and flux variations in the light-emitting diode (LED) emission are nonresolved challenges that need to be overcome in order to be used in final applications. We demonstrate two strategies that can be used to efficiently and precisely generate arbitrary spectral power distributions (SPDs) using multichannel LED engines. First, we introduce different methods to match a given SPD and select an algorithm (simulated annealing) in virtue of its speed (in the milliseconds range) and accuracy (color shifts Δu^′v^′ < 5 × 10^− 4). Then, we propose a closed-loop feedback control (PID) to compensate for spectral shifts due to temperature changes or lumen decay of the LEDs. Both methods can be used independently, but only a combination of them (which uses the output of the first method as an initial guess for the second) offers fast computational times and high spectral accuracy and precision. Computation times are important because these algorithms are intended to be executed on dedicated microprocessors integrated in the LED modules, often sharing scarce memory and processing resources. The results presented here are aimed to be universal and hold for different implementations of the light engine and any number of LED channels.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Aleix Llenas and Josep Carreras "Arbitrary spectral matching using multi-LED lighting systems," Optical Engineering 58(3), 035105 (29 March 2019). https://doi.org/10.1117/1.OE.58.3.035105

Received: 20 February 2019; Accepted: 14 March 2019; Published: 29 March 2019

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