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I wonder if such strong IR light is capable of harming the eye, even if we're unable to see it. High power LEDs in the visible spectrum are terribly bright, an

I wonder if such strong IR light is capable of harming the eye, even if we're unable to see it. High power LEDs in the visible spectrum are terribly bright, and when I accidentally get them shined into the eye, it really feels concerning if any harm has been done.

fitzroy 4y ago
Aren't traditional (non-LED) lightbulbs that get hot much higher in the IR spectrum since they're dissipating most of their energy as heat?
- Zak 4y ago
  Bright visible light causes the pupil to constrict and triggers an instinct to squint, blink, or look away. IR alone does not.
barelyauser 4y ago
We can stare at a burning campfire and barely get damaged. Long term exposure is another thing. The emitter power would have to be insanely high, or some kind of laser.
- drdaeman 4y ago
  Yes, but a campfire emits a lot of visible light, so our eyes adjust accordingly. While we're not cats with their amazing pupil dilation, we have some too. If one wears an IR-shiny hood, they may be at higher risk in the low-light conditions, if their eyes adjust to the dark, brain not realizing they're flooded with IR.
  - barelyauser 4y ago
    Retinal damage is not the only kind of damage the eye can be subjected to. The cornea has no blood flow to cool itself and is fully exposed to incoming radiation.
- analog31 4y ago
  A campfire has radiance limited by its temperature. It can put out a lot of power, but that power can't be focused to a high energy density at your retina. An LED can be nearly a point source, and can deposit a lot of power at a small spot, i.e., "almost a laser." Moreover, being invisible, an IR LED doesn't cause your pupil to close. And LEDs have gotten powerful enough to be dangerous. The regulations for optical radiation exposure now cover LEDs as well as lasers.
engineer_22 4y ago
Good question, this guy seems to have studied this question: https://medium.com/@alex.kilpatrick/ir-illumination-and-eye-safety-f0804673ca7 https://medium.com/@alex.kilpatrick/ir-illumination-and-eye-... He concludes: "If you buy the largest IR floodlight available on Amazon and you stare at it 200 mm (~7") from your face for more than 1000 seconds (~ 16 minutes) there is a possibility you might damage your cornea. So don’t do that. And I doubt anyone would do that because these things get pretty hot at that distance."
spcebar 4y ago
"Why do my eyes feel spicy?"
snerbles 4y ago
Near-IR aiming lasers (such as the AN/PEQ-2 and AN/PAQ-4) can indeed cause permanent damage, among USAF CATM armorers there was a rumor of at least one idiot burning his retina trying to "see" the beam directly.

fitzroy 4y ago

Aren't traditional (non-LED) lightbulbs that get hot much higher in the IR spectrum since they're dissipating most of their energy as heat?

Zak 4y ago
Bright visible light causes the pupil to constrict and triggers an instinct to squint, blink, or look away. IR alone does not.

barelyauser 4y ago

We can stare at a burning campfire and barely get damaged. Long term exposure is another thing. The emitter power would have to be insanely high, or some kind of laser.

drdaeman 4y ago
Yes, but a campfire emits a lot of visible light, so our eyes adjust accordingly. While we're not cats with their amazing pupil dilation, we have some too. If one wears an IR-shiny hood, they may be at higher risk in the low-light conditions, if their eyes adjust to the dark, brain not realizing they're flooded with IR.
- barelyauser 4y ago
  Retinal damage is not the only kind of damage the eye can be subjected to. The cornea has no blood flow to cool itself and is fully exposed to incoming radiation.
analog31 4y ago
A campfire has radiance limited by its temperature. It can put out a lot of power, but that power can't be focused to a high energy density at your retina. An LED can be nearly a point source, and can deposit a lot of power at a small spot, i.e., "almost a laser." Moreover, being invisible, an IR LED doesn't cause your pupil to close. And LEDs have gotten powerful enough to be dangerous. The regulations for optical radiation exposure now cover LEDs as well as lasers.

engineer_22 4y ago

Good question, this guy seems to have studied this question: https://medium.com/@alex.kilpatrick/ir-illumination-and-eye-safety-f0804673ca7 https://medium.com/@alex.kilpatrick/ir-illumination-and-eye-... He concludes: "If you buy the largest IR floodlight available on Amazon and you stare at it 200 mm (~7") from your face for more than 1000 seconds (~ 16 minutes) there is a possibility you might damage your cornea. So don’t do that. And I doubt anyone would do that because these things get pretty hot at that distance."

spcebar 4y ago

"Why do my eyes feel spicy?"

snerbles 4y ago

Near-IR aiming lasers (such as the AN/PEQ-2 and AN/PAQ-4) can indeed cause permanent damage, among USAF CATM armorers there was a rumor of at least one idiot burning his retina trying to "see" the beam directly.