The human eye can see ‘invisible’ infrared light - The Source - Washington University in St. Louis (source.wustl.edu)

submitted 4 months ago by fossilesque@mander.xyz to c/science@mander.xyz

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[-] SheeEttin@programming.dev 34 points 4 months ago

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.

[-] Valmond@lemmy.mindoki.com -1 points 4 months ago

Also, isn't it wildly known that some people see some shades of infra rouge?

[-] vampire@lemmy.world 22 points 4 months ago* (last edited 4 months ago)

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.

[-] Zikeji@programming.dev 12 points 4 months ago

I had just assumed those were supposed to be visible. Like the lights the Xbox Kinect had.

But if they aren't, that's annoying lol. Same deal with hearing the high pitch frequency old CRTs would emit.

[-] CookieOfFortune@lemmy.world 16 points 4 months ago

The CRT thing is pretty common I think, you just lose your high frequency hearing as you age.

[-] bitchkat@lemmy.world 13 points 4 months ago

The high pitch squeals just move to inside your head.

[-] CookieOfFortune@lemmy.world 4 points 4 months ago

Ugh this has become very true as I’ve aged :’(

[-] 474D@lemmy.world 3 points 4 months ago

I lost it at a Cypress Hill concert

[-] Zikeji@programming.dev 2 points 4 months ago

Yeah, I was using it as an example of annoying things fitting around the same niche lol.

[-] UPGRAYEDD@lemmy.world 3 points 4 months ago

Its not intentional as much as it is a cost savings

[-] UPGRAYEDD@lemmy.world 6 points 4 months ago

Thats mostly because the vast majority of IR lights and led's also emit visable light. To get an ir light to not also emit within the visable light spectrum is much more expensive.