Towards intelligent illumination systems: from the basics of light science to its application

Abstract

AbstractThe development and design of lighting systems is closely linked to the physiology of the human visual system. Whereas with the first generation of light sources, the visual appearance of objects in an illuminated environment was only possible by adjusting the level of illuminance. In contrast, with modern semiconductor light-emitting diode (LED) systems, the emitted spectrum can be flexibly varied. This new degree of freedom has led to an interdisciplinary field of research, aiming to explore the effect of light on humans in terms of physiological, psychological and cognitive parameters and to model their mechanisms or make them quantifiable via mathematical metrics. Today’s quality assessment of light spectra is composed of metrics that combine colour perception, contrast sensitivity, visual sensation, non-visual responses and cognitive preference. A lighting system that takes these aspects into account is commonly referred to as an integrative lighting solution or Human Centric Lighting. This article describes the current knowledge about the human eye’s visual and non-visual processing system, the development of colour rendering metrics, and the light-induced effect on nocturnal melatonin suppression. Then, the basic concept of an intelligent and individually adaptable lighting system will be discussed.Practical Relevance: This article deals with the basics of light science and covers the fundamental aspects of intelligent lighting systems, which with the help of multi-channel LED luminaires, could address the visual properties of light and the human circadian system separately via metameric spectra.