March/April 2020
Lighting metrics
TUNNEL VISION? Our traditional photopic-focused understanding of light is increasingly irrelevant and narrow, argues Stephen Cannon-Brookes. Is it time for a radical rethink? s we struggle to accommodate the emerging goals generated by rising concern for human wellbeing, siege is about to be laid to many of the core tenets that underpin our current understanding of light. It is easy to underestimate the influence that has been exerted by the definition of visible light using
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the photopic spectral sensitivity function known commonly as VÎť V Îť . It has given us a tool to measure and deliver light, but it has also encouraged us to regard the visible spectrum of light independently of its close neighbours, ultraviolet and infrared radiation, encouraging the implied disconnection of vision from the wider sensory system. At the
risk of mixing metaphors, future generations will regard this period as one of tunnel vision. The discovery of the blue-light-stimulated melanopsin generators in the retina has rendered our classical photopic-focused understanding of light an increasingly creaking edifice. Addressing this, however, is a challenging prospect for the multiple generations brought up on an orthodoxy that also unpins our understanding of colour. However, in doing so we may be able to appreciate what has made it so difficult to understand a range of phenomena and cultural interpretations or beliefs that seem alien or inexplicable. Examples of the latter can be seen in relating colours to different energy centres or chakras in the body, and our still rudimentary engagement with a new, or perhaps rather old, awareness of the natural environment known as biophilia.
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