Welcome to the lighting revolution
In lighting applications, the adoption of light-emitting diodes (LEDs) and organic LEDs promises to reduce lighting energy use dramatically over the next few decades. There is an equally marvellous scientific revolution in biology and psychology. In 2002, we learned conclusively that there is a class of photoreceptive cells in the retina, the intrinsically photoreceptive retinal ganglion cells (ipRGCs), that is separate from the rod and cone cells that transduce visual signals (1). Thus, the eye-brain connection is far more complex than previously thought, and the more we learn the more complex we find it to be (2). Ever since this discovery, debate has raged concerning how to apply this knowledge, and how quickly to do so (3).
One reason for caution is that lighting installations serve many functions, and our recommendations reflect this complexity. As I wrote in a previous blog entry, lighting quality exists at the nexus of the needs of individuals, the environmental and economic context, and architectural considerations. Strong evidence is needed to intelligently blend new discoveries into coherent guidance in balance with the other considerations.
Simplified schematic diagram of two eye-brain pathways, taken from CIE 158:2009. Light received by the eye is converted to neural signals that pass via the optic nerve to these visual and non-visual pathways. POT = Primary optic tract. RHT = Retino-hypothalamic tract. LGN/IGL = Lateral geniculate nucleus / Intergeniculate leaflet. SCN = Suprachiasmatic nucleus of the hypothalamus. PVN = Paraventricular nucleus of the hypothalamus. IMLCC = Intermediolateral cell column of the spinal cord. SCG = Superior cervical ganglion. CRH = Corticotropic releasing hormone. ACTH = adrenocorticotropic hormone. (c) CIE, 2009. Used by permission.
This is a time of revolutionary change in the lighting industry. Solid-state lighting (SSL) systems are on track to achieve lighting efficacies for general lighting in excess of 150 lumens per watt (lm/W) in the not-too-distant future. This is double the typical performance of the ubiquitous linear fluorescent systems in use in commercial spaces today, and 10x the efficacy of the familiar incandescent light bulb, which many countries have regulated out of use in many applications in recent years. The total system performance could be further improved by the addition of smart controls, which include occupancy sensing and daylight harvesting, among other features.
Lighting quality is contextual, being a function of meeting the functions of the space (here expressed as individual well-being of people in buildings), while taking into account the economic and environmental context and the physical setting (here expressed as architectural considerations). Credit: (1).
Have you ever tipped back your head and looked up at the immensity of the night sky, clothed with twinkling stars, wandering planets, itinerant comets and the flash of the International Space Station whizzing by? An impressive sight even from the city , if you’re privileged enough to be on top of a volcano in the middle of the Pacific such as Mauna Kea, the garland of the Milky Way and billions of shining stars strewn about it, carelessly, are awe inspiring. Now imagine instead that you took a ride on one of those comets as it was speeding toward the earth or perhaps you’re more conservative and suffering from a touch of motion sickness, imagine you were floating about the cupola of the International Space Station having turned a few somersaults and took a look at our beautiful, blue planet as the sun set, what would you see? Vast expanses of darkness, interspersed with twinkling lights, immense oceans bordered by pulsating city lights. A delicately poised universe, lit up with lights of every kind, incandescent, fluorescent and most recently Light Emitting Diode (LED) lights.
Visible Earth, Night Lights. Credit: NASA.
One of my favourite things about working with light-based art is its endless capacity to surprise and delight people from all walks of life. Light transcends language barriers, appeals to all ages, and doesn’t require a degree in art history to appreciate its beauty, or how innovatively it can be used.
Aeolian Light by Squidsoup. Credit: Joel Chester Fildes.
Light continues to fascinate the scientific community. With such a broad set of applications often the only limit is the imagination. From Malaria through to manipulating individual cells light is currently turning up in the most unexpected places as a key enabling technology. In this article we are going to look at these unexpected uses of light in the field of biomedical science.
Light-based approaches can help fight Malaria. Credit: Wikimedia Commons.