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sábado, enero 28, 2023

Minimizing the glare of L.E.D. lights for safer night time driving

A team of researchers from China and the Netherlands have become the first to look into and evaluate the effect of the levels of discomfort glare – the urge to look away from a bright light – in L.E.D. road lights.

While the use of light emitting diode technology or L.E.D.s are rising – mostly due to their energy-efficiency – there is some concern that the harsh glare of L.E.D. lights could be a safety concern.

A team of researchers from China and the Netherlands have become the first to look into and evaluate the effect of the levels of discomfort glare – the urge to look away from a bright light – in L.E.D. road lights.

While our vision can adapt to the surrounding darkness of nighttime driving conditions, sudden stabs of brightness – say like from road lamps – can be irritating, distracting and even painful.

“Glare has a strong effect on the normal visual function, causing a serious threat to safety. And the accumulative effect of glare also threatens the physiological health of the human body,” said Yandan Lin, an associate professor and director of the Vision and Color Research Laboratory at Fudan University.

“We believe that the lighting industry has an urgent need to update the ways to characterize discomfort glare caused by L.E.D. road lights,” said Mr. Lin.

The discomfort glare of L.E.D.s tend to be greater than that of traditional streetlights because of several factors. One is that L.E.D.s are designed to emit the same amount of light as conventional bulbs but from a smaller area. Another big factor is that white L.E.D.s have more energy in the blue part of the spectrum. Blue light is perceived as brighter to the human eye, increasing glare.

With these factors in mind, the team created a model to predict the level of discomfort experienced by drivers under different lighting conditions.

The floors and walls of a laboratory were pained completely black and a collection of light sources were placed around the room to simulate the illumination from an L.E.D. streetlamp as it would appear to a driver on a dark road. The researches adjusted the light sources to create 72 different lighting conditions. Under each of these conditions, volunteers were asked to rate their level of discomfort glare.

Around four different lighting parameters were systematically modified during the experiments: the luminance (i.e., the luminous intensity of light per given area) of the L.E.D. lights, the background luminance, the apparent size of the L.E.D. lights from the perspective of the observers, and the angle between the L.E.D.s and the line of sight of the observers.

They found that the interaction between luminance and the size of the lights from the observers’ perspective was most responsible for the amount of light hitting an observer’s eyes and the level of discomfort glare.

To minimize discomfort, they recommend minimizing both the amount of light hitting the eyes and the luminance contrast between the streetlights and the background. This can be accomplished through good optical design of the L.E.D. lights and careful placement of streetlights.

The researchers hope that this model can be put into immediate used by design and construction firms in the process of replacing regular streetlights and other roadside lights with L.E.D.s.

The team plans to continue with their investigation into glare, looking at the physiological effects. This would allow the researchers to make more concreate measurements of discomfort by using factors such as eye movement and pupil size. – EcoSeed Staff

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