Interesting web page discussing the optics of the eye and wavelength

[Alaskan]

Why can't we see infrared light?

While explaining to my nephew about the physics of light, I told him we cannot see infrared color, and he kicked back with a very simple question: why can't we see it? I could not tell him. Is the ...

physics.stackexchange.com

 

[kecked]

You can only infer it. You can’t see it directly.....and only When very mad

 

[Alaskan]

You can see some of the NIR infrared if it is powerful enough, but it takes a lot and god forbid it is from a laser source with a lens or not, the lens in your eye will focus it down to a burning spot on your retina.

 

[CurtisOliver]

People that find 405nm blurry may very well be able to see NIR more clearly. I know I can see 808nm no problem, not sure about longer wavelengths as I haven't had the chance to view any really. The only other one would be 946nm inside my 473nm when I opened it up, but can't recall if i observed IR there or not. I have even compared 808nm with 650nm to see if there is a slight difference in colour. One interesting eye effect I have observed at night is grey light. When you observe light of very low intensity, there is enough photons to trigger your eye to see it, but not enough for you to observe its colour. I'm wondering it some people here would be able to 1064nm if in total darkness but not as red, but grey faint light.

 

[Alaskan]

Curtis, I will try that, hadn't heard of grey light before. I can see 808 nm clearly, but not 946 nm, I will try it after my eyes are adjusted to the dark and see if it produces a spot. BTW, 405 nm is extremely blurry to my eyes.

 

[CurtisOliver]

To be honest neither had I, I experienced it for myself a while back with a dimmable blue LED lamp. I turned it on and slowly dimmed it to as low as it could go. The threshold for the LED must of been really low, as I could still see that it was on when looking at it, but looking where it was illuminating all I could see was grey. I slowly started to increase the intensity, and sure enough where I was seeing the grey started to turn blue. Whether it will work the same for intense IR light I don't know. 440-460nm light is not too far away from the scotopic peak so it may have had something to do with why i could still see it.

 

[kecked]

Infrared....infer it.....seeing red .....mad....

 

[Alaskan]

Oh duh, I was still scratching my head

 

[paul1598419]

I can also see 808nm dimly as a red color, but 1064nm is a whole other story. I'm not aware of anyone who can see that far into IR. And it goes without saying that far IR in CO2 lasers is impossible to see. It seems we can only really see in the very near IR.

 

[CurtisOliver]

It would be interesting though if it was possible to make out the slightest light from 1064nm but it is probably too out of range. 946nm however might be more achievable under the right conditions

 

[hwang21]

It is possible to see 1064nm light - I seem to recall that I as well as a couple other members on the forums confirmed seeing it when this topic came up on the forums ~5 years ago. If you have access to 1064nm light, get yourself into a pitch black room (as in, you cannot see your hand in front of your face dark) for an hour (to fully adapt your eyes to the dark - no phone, no flashlight, nothing - not even an emission indicator/LED on the laser if possible) and then turn on the laser and see if you can see a very faint pinkish-red dot

FWIW, I also find 405nm very fuzzy - the dot actually seems to be hovering/floating on top of the wall instead of hitting the wall and diffusing/reflecting off, if that makes sense

Check out this paper: https://www.osapublishing.org/josa/abstract.cfm?uri=josa-66-4-339

 

[barthchris]

My peepers suck as age, especially night vision(only 46, look young, feel old). Laser damage ---maybe but I do have an eye doc friend who I met in a drone racing club that looked at my retnias with specialized equipment and saw no damage. BTW the eye doc is a laser nerd. Got his start in optics begging parents to stop by the old Edmund scientific store off the NJTP in Barrington NJ. I did the same, no damn lasers in the showroom but still plenty of cool stuff for a nerdy kid. I would have had a field day as an adult with the surplus lenses wrapped in tissue paper. My prized possession was the ant/cockroach burning a 12x12x1/4" thick Frenzel lens. Even had the non nerds lined up on the playground to watch and "smell" the results(ewwwww)!!! Back then teachers didnt care. Lol!

Eye doc had no idea these powerful light amplifying diodes were so cheap. Linked him here and to DTR. He's hooked. Will probably post/join soon. Very smart responsible guy, along with his private practice in Bethesda MD he also does procedures at Georgetown in DC. I took a different path, hormones temporarily ruined my "nerdiness" at the worst time possible. Now Im an electrician. Have my masters license but its still very much grunt work and hard on the body.


After meandering off subject... Lol! Id like to try a 405 with my father. He just had the lens replaced in his eye and reports he can see colors he's never seen(or remembers) before, especially on flowers. The eyes lens degrades as we age. In the dark look in the mirror with a UV flashlight and an angle and prepare shocked by the erie yellow your lens gives off. My kids dont have this..

I can see the dim rec glow of a malfunctioning 532Of course I didnt stare at it but we've all seen it so don't act like Im the dangerous dummie here lol!!!

Side note.. My dog can see cheap 405nm pens even in daylight. I cant see crap. Lol!

 

[kecked]

You ain’t seeing 1064...... if anything its some other non linear effect bringing it up in the 700-800 range. It is also really dangerous to try. Your eyes don’t cry if you f it up. If you take the cornea off there have been reports of seeing father into the ir. Read about it but yea no try