Tunable multiple-LEDs combination spectrum for plants based on McCree PAR spectrum

In this paper a tunable Light Emitting Diodes' (LEDs) spectrum is proposed to match the plant's spectrum based on the relative quantum efficiency (RQE), proposed by McCree as a reference curve. Various LED spectra with different peak wavelengths are combined into a single one, in order to match the reference target spectrum. Based on optical and electrical experiments, nearly monochromatic LED spectra are measured. A multi-Gaussian function is adopted in order to model the best fitting of the different LED's spectrum. Three different kinds of LED combinations are proposed in order to achieve the optimal spectrum for plants. MATLAB simulation is used to show the matching of LEDs using the proposed LED combinations.