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 LEDs or light bulbs.
Lasers are extremely narrowband, 10x narrower than the blue LEDs used in 'white' lighting LEDs, 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. 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 before two adjacent bowls of fruit separated by barrier.
Each bowl was randomly illuminated by: warm, cool, or neutral white LEDs; 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 combinations of light sources.
There was a statistically significant preference for the laser-based white light over the warm and cool LED-based white light, said Sandia scientist Jonathan Wierer, but no statistically significant preference between the lasers, neutral white LED or incandescent source.
The results probably won't start a rush to sell laser-based lamps, said Tsao, but they may open an ignored line of research.
BMW is considering using blue laser diodes for next-generation car headlights, according to Sandia, while the other three colours are not yet efficient enough for lighting use.
The research was published in the Optics Express.