Laser lighting options are about to get some long overdue attention
Sceptics thought laser light would be considered too harsh to be acceptable for general domestic use, but a researcher in the US suggests the sceptics were wrong.
US researchers at Sandia National Labs have demonstrated that people are comfortable with viewing objects lit by four coloured lasers - blue, red, green, and yellow - instead of white LED’s or light-bulbs.
Lasers are extremely narrow band, 10 times narrower than the blue LED’s used in 'white' lighting LED’s, and even further from the continuous spectrum of sunlight.
"What we showed is that diode lasers are a worthy path to pursue for lighting," said Sandia researcher Jeff Tsao.
"Before these tests, our research in this direction was stopped before it could get started," said Tsao. "The typical response was, 'Are you kidding? The colour rendering quality of white light produced by diode lasers would be terrible.'
"So finally it seemed like, in order to go further, one really had to answer this very basic question first."
In the tests, 40 volunteers were seated one by one in front of two adjacent bowls of fruit separated by barrier.
Each bowl was randomly illuminated by: warm, cool, or neutral white LED’s; an incandescent light bulb; or by the combined lasers tuned to appear white - Sandia has not revealed the chosen colour temperature. The subjects were asked which bowl they preferred under 80 different combinations of light sources.
The research, published in Optics Express, found that there was a statistically significant preference for the laser-based white light over the warm or cool LED-based white light, according to Sandia scientist Jonathan Wierer, but no statistically significant preference among the lasers, neutral white LED’s or incandescent sources.
The results will probably not start a rush to sell laser-based lamps, said Tsao, but they may open an ignored line of research.
BMW is considering the possibility of using blue laser diodes for its next-generation car headlights, according to Sandia, while the other Three colours are not yet efficient enough for light use.
[Steve Bush, Electronics Weekly]
