Lighting in Design February-March 2016

Incandescent lamps not quite dead

by Gavin Chait

H ave you ever have one of those flash-backs where you tick off your teacher and she sets you an enticing essay topic as punishment? You know the ones: the inside of a tennis ball; the aerodynamics of a gecko’s toenail; my life as a light- bulb. A topic designed to give you perspective on your sins, the vastness of the universe, and your insignificant part therein. So, with a backward glance over my shoulder to where my teacher is standing with the old yellow ivory ruler she used to punish me, let me begin. My entire house is filled with low-energy com- pact fluorescent lamps, except for two fittings: one over the dining-room table and the other over the main bedroom. Whenever I switch on either of these two lights, the local electricity generators spring into action to add fundamental new capacity to the grid lest the whole thing collapse, and my bank-manager springs a surprise charge onto my overdraft.

Each of these lamps contains a delicate and intricately-laced squirrel cage tungsten filament, hand-knotted by skilled Mesopotamian artisans, within free-blown glass enclosures made from silica scraped from the walls of the caves beneath the Vatican. Each light draws an astonishing 60W, and offers a very warm white light with a colour temperature of 2700 K, even such as the light that graced our antediluvian forebears as they strode bravely beneath the sunshine. My wife loves them. Which is a pity, because incandescent lamps are gradually being legislated out of existence in favour of LEDs and fluorescents. Except for some new research coming out of MIT, that is. In ‘Tailoring high-temperature radiation and the resurrection of the incandescent source’, Ognjen Ilic, Peter Bermel, Gang Chen, John Joannopoulos, Ivan Celanovic, and Marin Solja Č i Ć of the Research Laboratory of Electronics at MIT have taken an ap- proach to improving dielectric coatings and applied them to incandescent lighting. A standard incandescent lamp is manufactured from a tungsten filament. When current passes through, it promptly heats up to about 3000 K

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LiD FEB/MAR 2016