LIGHTING SPECIAL
BR I GHT I DEAS The quest for colour-perfect, user-friendly lighting continues – and 2025 might just deliver, says Phil Rhodes
M aking a candle requires some wax and a piece of string. Making LED lights requires a semiconductor foundry and an electronics manufacturing plant. There’s a reason for all that tech: it gives us options. Historical lighting had just one control and rarely strayed from its intended colour. Recapturing that simplicity has been a design goal since the advent of LED lights, and 2025 might see a bit of progress in that direction. The simplicity of classic lighting – tungsten light bulbs, sunlight and candles – lies in the fact that they emit light by glowing due to heat. LEDs, along with fluorescent tubes and HMIs, don’t glow because they’re hot, yet an immense effort has gone into making
them mimic this behaviour. Even so, the challenge goes beyond producing white light. We want lighting with the colour quality of an open flame, paired with high efficiency, ease of use and all the modern conveniences in one device. Understanding this starts with knowing how LEDs produce white light. We might try combining red, green and blue to create a light that looks superficially white when directed at a grey card. Shine it on something orange, however, and the limitation becomes apparent: the orange reflects wavelengths of orange light, which sit between red and green on the spectrum. It might reflect some of the light from the red LEDs, but it probably doesn’t reflect much green, so we get a neon-red blood orange.
It will also make human beings look blotchy and florid, which is why we don’t make movie lights out of RGB clusters (repurposed disco lights and virtual production video walls notwithstanding). The solution which changed the world was to coat a blue LED with a yellow- emitting fluorescent phosphor. The two combine to look approximately like something hot enough to glow. In early designs, that might have been very approximate. Many late nights in R&D labs around the world yielded enough improvement for us to rely on it for everything, from flashlights to film sets. It’s an imperfect solution, often lacking teal and deep blue. A phosphor can only make light redder. It can turn blue into red, orange or green, but it can’t turn blue
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