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Topics: Science, US News, Washington
Joe Yates
Out of every person to have ever lived on Earth in the millions of years since humans first appeared, only five people have been able to witness a color that has possibly been around since the beginning of time.
Of those who saw the 'dazzling' color, three of them were researchers on the team, while two of them were just colleagues from the University of Washington, in Seattle.
In order for it to be seen, a 'technicolor technique' had to be designed and created. As to why a laser - which has been dubbed 'Oz' - was needed, I'll have to talk a little about the biology behind it.
Our retinas have three kinds of cone cells—specialized photoreceptors that sense different wavelengths of light. S cones are most sensitive to shorter wavelengths, which correspond to blue. M cones respond to medium wavelengths, perceived as green. And L cones are tuned to longer wavelengths, which we see as red.
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The brain takes input from all three types and blends them together, giving us the rich, full-color vision we experience.
However, each cone type doesn’t work in isolation—their sensitivity ranges overlap. That means light that stimulates M cones, for example, can also trigger either S or L cones, depending on the specific wavelength.
Professor Ren Ng, of electrical engineering and computer science at Berkeley's University of California, explained to Scientific American: "There’s no light in the world that can activate only the M cone cells because, if they are being activated, for sure one or both other types get activated as well.
“The name comes from the Wizard of Oz, where there’s a journey to the Emerald City, where things look the most dazzling green you’ve ever seen,” Ng told the publication.
Ng is one of the five people who saw the color, named 'olo' - which he described as 'blue-green with unprecedented saturation'. The closest color that compares is teal.
The abstract to the paper read: "We introduce a principle, Oz, for displaying color imagery: directly controlling the human eye’s photoreceptor activity via cell-by-cell light delivery.
"Theoretically, novel colors are possible through bypassing the constraints set by the cone spectral sensitivities and activating M cone cells exclusively. In practice, we confirm a partial expansion of color-space toward that theoretical ideal.
"Attempting to activate M cones exclusively is shown to elicit a color beyond the natural human gamut, formally measured with color matching by human subjects. They describe the color as blue-green of unprecedented saturation."
It continued: "Further experiments show that subjects perceive Oz colors in image and video form. The prototype targets laser microdoses to thousands of spectrally classified cones under fixational eye motion.
"These results are proof-of-principle for programmable control over individual photoreceptors at population scale."