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Cutoff wavelength of human eyesight

bostjan

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I always read that human sight ranges from 400 nm - 700 nm, but, IME, that's way off.

For example:

365 nm super high intensity LED looks bright to me. (not sure what the q-factor is though)
808 nm laser is obviously not super bright, but at 200 mW, I can see the dot very clearly.
940 nm high intensity LEDs look dimly lit to me - I can't see light reflecting off of surfaces, but I can see the LEDs themselves in the dark. There is essentially no light coming from those below 820 nm, and very very little below 850 nm. Technically, they should be completely invisible.

Am I a mutant, or is the published range just totally wrong?
 



julianthedragon

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I've read other cases of people seeing below 400nm and seeing 808nm as a deep red. One explanation is that everyone's eyes have slightly different limits but 400-700nm fits the average of most human eyes. Explanation 2: laser diodes have an emission spectrum wider than just a singular wavelength, so maybe you're getting a glimpse of the emission in the "visible" range. Explanation 3: while you might see traces of light <400 or >700, you're not seeing additional colors, just dimmed versions of violet or red, maybe the visible spectrum stops where different colors stop being perceived. Or option 4 you could be a teenage mutant ninja turtle
 

gazer101

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Alot of times surfaces can react with laser light to make it visible, my 2W 845nm laser dot is just barely visible in a dark room for this reason afaik
 

CurtisOliver

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I know for a fact I can see 808nm and some can’t. However I struggle more at short wavelengths. 405nm is visible but a blur which i know some have the ability to see properly. I have wondered if there is a correlation between those that see <420nm as a blurry spot and those that can see near ir. Our ultimate limits of our vision will depend on when we observe grey light. This is when there is enough photons to excite the rods in our eyes but not enough to activate the cones responsible for seeing colour. For this to work your eyes need to be adapted to a very dark environment for a while. And then exposed to a very dim light source.
 
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WizardG

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My wife thinks I'm crazy but I swear I can see an extra band in a rainbow. To me it looks like there's a faint white band past the violet.
 

ZRaffleticket

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Try a 365nm led and a diffraction grating, I see it go from bluer to more violet and bluer again.

For what it's worth, to me 355nm is a gray spot (likely some sort of fluorescence) with a blue blur around it.
 

bostjan

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I've read other cases of people seeing below 400nm and seeing 808nm as a deep red. One explanation is that everyone's eyes have slightly different limits but 400-700nm fits the average of most human eyes. Explanation 2: laser diodes have an emission spectrum wider than just a singular wavelength, so maybe you're getting a glimpse of the emission in the "visible" range. Explanation 3: while you might see traces of light <400 or >700, you're not seeing additional colors, just dimmed versions of violet or red, maybe the visible spectrum stops where different colors stop being perceived. Or option 4 you could be a teenage mutant ninja turtle
I've checked my 808 nm with a spectrometer and it's definitely not outputting anything detectable below 800 nm.

I tested my wife's eyes with the spectrometer and she told me she couldn't see anything above 800 nm.

So, it looks like there are a few documented mutations in the L cones of the eye (the ones that see red), but there's not a lot of work written about those mutations. I think it might be likely that some people can see deeper into NIR than others for genetic reasons. My whole life I've been extra sensitive to sunlight, and maybe that's part of the reason why. My son is the same way, so I bet that if it is some sort of genetic mutation, he's got it too.

It looks like the UV thing is different. The S cones (the ones responsible for blue light detection) are sensitive to wavelengths lower than what the eye can see, because the lens reflects some of the shorter wavelengths. My right eye's lens was damaged when I was a teenager, but healed so that I can now see a little better out of my right eye than my left (it was the opposite case for me throughout my 20's and 30's). Maybe coincidentally, or maybe not, my right eye is much more sensitive to UV LEDs.


Alot of times surfaces can react with laser light to make it visible, my 2W 845nm laser dot is just barely visible in a dark room for this reason afaik

React through some sort of fluorescence? I think I can rule that out, since I've checked my IR sources through an optical spectrometer. Fluorescence under UV is far more common, and might account for the UV reaction. Bright UV light, to me, always looks blurry. Even 405 nm laser light appears diffuse to me when otherwise apparently focused into a point. Perhaps something in my eye is fluorescing, maybe even my eye's lens, making UV light appear as hazy flashes.

I know for a fact I can see 808nm and some can’t. However I struggle more at short wavelengths. 405nm is visible but a blur which i know some have the ability to see properly. I have wondered if there is a correlation between those that see <420nm as a blurry spot and those that can see near ir. Our ultimate limits of our vision will depend on when we observe grey light. This is when there is enough photons to excite the rods in our eyes but not enough to activate the cones responsible for seeing colour. For this to work your eyes need to be adapted to a very dark environment for a while. And then exposed to a very dim light source.

Can you see 808 nm? Do you personally know people who can't see the same light sources others can see under the same conditions? I guess that's what started me down this road, so probably you've already been there.

My wife thinks I'm crazy but I swear I can see an extra band in a rainbow. To me it looks like there's a faint white band past the violet.
Try a 365nm led and a diffraction grating, I see it go from bluer to more violet and bluer again.

For what it's worth, to me 355nm is a gray spot (likely some sort of fluorescence) with a blue blur around it.

Very interesting. UV, including 405 nm just looks white to me.

I haven't looked at my UV sources through a grating yet. That'll be the next logical step. It sounds like a lot of you have already noticed the same things. I won't be too surprised to find out that there is some sort of known physiological explanation for everything I'm observing that just isn't yet common lay knowledge.
 

Sowee7

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I've checked my 808 nm with a spectrometer and it's definitely not outputting anything detectable below 800 nm.

I tested my wife's eyes with the spectrometer and she told me she couldn't see anything above 800 nm.

So, it looks like there are a few documented mutations in the L cones of the eye (the ones that see red), but there's not a lot of work written about those mutations. I think it might be likely that some people can see deeper into NIR than others for genetic reasons. My whole life I've been extra sensitive to sunlight, and maybe that's part of the reason why. My son is the same way, so I bet that if it is some sort of genetic mutation, he's got it too.

It looks like the UV thing is different. The S cones (the ones responsible for blue light detection) are sensitive to wavelengths lower than what the eye can see, because the lens reflects some of the shorter wavelengths. My right eye's lens was damaged when I was a teenager, but healed so that I can now see a little better out of my right eye than my left (it was the opposite case for me throughout my 20's and 30's). Maybe coincidentally, or maybe not, my right eye is much more sensitive to UV LEDs.




React through some sort of fluorescence? I think I can rule that out, since I've checked my IR sources through an optical spectrometer. Fluorescence under UV is far more common, and might account for the UV reaction. Bright UV light, to me, always looks blurry. Even 405 nm laser light appears diffuse to me when otherwise apparently focused into a point. Perhaps something in my eye is fluorescing, maybe even my eye's lens, making UV light appear as hazy flashes.



Can you see 808 nm? Do you personally know people who can't see the same light sources others can see under the same conditions? I guess that's what started me down this road, so probably you've already been there.




Very interesting. UV, including 405 nm just looks white to me.

I haven't looked at my UV sources through a grating yet. That'll be the next logical step. It sounds like a lot of you have already noticed the same things. I won't be too surprised to find out that there is some sort of known physiological explanation for everything I'm observing that just isn't yet common lay knowledge.
My eyes behave weirdly when exposed to IR. 808nm and 850nm both look like a deep red to me. 900nm looks like a very deep red to me but it is still visible. 940nm looks deep blue to me? (Only when from a laser), it looks deep red from an led, 980nm looks cyan to me (also only from a laser). It looks almost invisible from an led. I've tested the 940 and 980nm lasers with a spectrometer and it only showed ir
 

CurtisOliver

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I vaguely remember seeing something about that in the past on LPF. Two photon absorption in your eye? 980/2=490nm (Cyan).
 

CurtisOliver

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That could be possible, I think its called two photon vision when it happens in the eye
Well yes. But two photon absorption is the phenomenon responsible. It’s an interesting phenomenon. Even more fascinating that it can occur in our own eyes.
 

Ears and Eggs

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Interesting, it does seem to vary a bit between people. I used to have a 200mW 808nm pen, and I could just see the dot, it was a very faint, very deep red, that appeared quite blurry. I do remember showing one of my friends this laser though and he couldn't see it at all. I have a 365nm UV LED and can see that too, it's a very blurry and pale violet color to me, kind of like looking through a ghost. Very hard to focus on.
 

kecked

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I was told that when working with my Ti:Saph around 800nm if I start seeing blue light it’s time to leave the room. It’s shg in the eye and indicative of high energy!
 




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