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Controllable spectrum artificial sunlight source system using LEDs with 32 different peak wavelengths of 385–910 nm
Author(s) -
Fujiwara Kazuhiro,
Yano Akira
Publication year - 2011
Publication title -
bioelectromagnetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.435
H-Index - 81
eISSN - 1521-186X
pISSN - 0197-8462
DOI - 10.1002/bem.20637
Subject(s) - light emitting diode , wavelength , sunlight , irradiance , materials science , optics , optoelectronics , absorption (acoustics) , diode , visible spectrum , led lamp , physics
Abstract This study developed a lighting system that produces an approximate spectral irradiance (SI) of ground level sunlight in the wavelength range of 385–910 nm (GLS 385–910 ) using 547 light‐emitting diodes (LEDs) with 32 different peak wavelengths. The produced SI can be modified over an arbitrary wavelength band. The SI at the light outlet reached up to 1/2 of the GLS 385–910 of a sunny April day, although the produced SI deviated from the GLS 385–910 at some wavelengths. For subsequent experiments, the reference SI was defined as 1/4 GLS 385–910 of a sunny April day. The SI produced from the lighting system was adjusted to approximate the reference SI. The ratios of the produced SI and the reference SI were within 0.72–1.28. As an application of the lighting system for biological studies, the transmitted SI of a green leaf of perilla ( Perilla frutescens L.) was investigated. The curve shape of the transmitted SI, which had characteristically low transmission percentages of blue and red light, reflected the characteristics of the absorption spectra of chlorophylls. The lighting system is therefore potentially beneficial for use in diagnosing physiological conditions of plant leaves, although its application is not limited to plant physiological studies. Bioelectromagnetics 32:243–252, 2011. © 2010 Wiley‐Liss, Inc.