SPATIAL LIGHT DISTRIBUTION CHARACTERIZATION AND MEASUREMENT OF LED HORTICULTURAL LIGHTS

摘要

The demands to light are different between plant and human, and the type and irradiation ways of the lighting products in horticultural and general lighting also vary greatly, thus the conventional characterization and measurement methods for spatial light distribution of general lighting products are no longer applicable for most horticultural lights. This paper studies the main light parameters affecting plant growth and the applicability and limitations of existing measurement instruments for spatial light distribution. A robot spectroradiometer is proposed to comprehensively measure the horticultural lights. Moreover, typical LED horticultural lights are measured, and comparisons show that the photosynthetic photon flux density (PPFD) distribution of a horticultural light should be investigated at distances close to practical applications, and not only the horizontal but also the inclined planes need be investigated. Furthermore, several quantities are proposed in this paper, e.g. using the uniformity of R/B ratio to characterize the spectral uniformity of irradiation.