Science

tl;dr:

The research was initiated after scientists on the research team reported seeing occasional flashes of green light while working with an infrared laser. Unlike the laser pointers used in lecture halls or as toys, the powerful infrared laser the scientists worked with emits light waves thought to be invisible to the human eye.

But packing a lot of photons in a short pulse of the rapidly pulsing laser light makes it possible for two photons to be absorbed at one time by a single photopigment, and the combined energy of the two light particles is enough to activate the pigment and allow the eye to see what normally is invisible.

“The visible spectrum includes waves of light that are 400-720 nanometers long,” explained Kefalov, an associate professor of ophthalmology and visual sciences. “But if a pigment molecule in the retina is hit in rapid succession by a pair of photons that are 1,000 nanometers long, those light particles will deliver the same amount of energy as a single hit from a 500-nanometer photon, which is well within the visible spectrum. That’s how we are able to see it.”

Neat! But please don't shine lasers into your eyes even if it's supposed to be invisible.

I've always been able to see the IR light from those depth sensing cameras used for facial recognition on laptops, as well as those sensors old android phones used to use to detect if they're face down on a table or up to your ear.

It just looks like dark red to me. My science teacher in highschool told me it's not common but some people have a wider spectrum of light thats visible to them than others. This special gift from nature has not meaningfully impacted my life in any way, shape, or form.

I can barely see normal visible red.

Stupid Deuteranomaly

• https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/color-blindness/types-color-vision-deficiency

Do you suppose the green flash phenomenon should be revisited? A combo of light, atmosphere and the human eye seems reasonable to me.