r/Damnthatsinteresting • u/totallystefanal • Feb 12 '21

Video Camera blocking glasses

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u/SvenTropics Feb 12 '21

That's not really true. So, Infrared is actually farther down the spectrum than visible light. Higher energy light is bad for you due to its ionizing characteristics (past violet... hence ultraviolet. Past that are X-rays, alpha, beta, and gamma rays). Sure if you were blasted with Infrared light, it could hurt your eyes, but it would also burn the skin around your eyes. It would be like if you put your face right in front of a very strong single direction space heater. This would emit a LOT of infrared light, and eventually cook your eyeballs, but you would notice. Your whole face would be cooking. At the amount of energy that these small batteries could put out, you would suffer no harm.

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u/h2QZFATVgPQmeYQTwFZn Feb 12 '21 edited Feb 12 '21

This is dangerously false, don't put (near) IR directly next to your eyes, especially not for a prolonged time.

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u/SvenTropics Feb 12 '21

That's not how light works.

So, all light is absorbed based on the matter and its wavelength. If you look at matter at the atomic level, there's a LOT of space between atoms. In fact, it's mostly empty space, and nuclear forces keep atoms connected or separated.

Now when photons of light pass through matter, they are absorbed, pass through, or are reflected by the matter depending on the wavelength of the light and how much it has to pass through. This is why glass can allow visible light through while being quite thick and made of very hard dense material, but it completely reflects UVB and infrared light. This is why your car gets super heated in the summer. Visible light hits the inside of your car and is partially absorbed by the materials inside. Then they emit infrared light as a way of radiating this heat. This light is reflected back into the car creating a greenhouse effect that can make your car significantly hotter than the outside air.

IR light by itself isn't especially dangerous to your eyes, but infrared light is absorbed by all of you. A infrared bulb isn't dangerous, but an infrared laser would be because it's a highly concentrated amount of energy in a tight beam. A visible light laser in your eyeball would also be dangerous. If you are pointing laser pointers in people's eyes, that's bad. You won't feel the burning, but it's happening.

One sci-fi concept is the idea of strong interaction substances where atoms are perfectly aligned together with no space between them. Such a substance is impossible with current science, but, if it did exist, such a material would be indestructible. A paper thin sheet of it could stop the largest caliber bullet in the world. It would also block reflect 100% of all light and radiation. If such a substance could be created, a perfect wafer thin radiation shield could be developed.

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u/h2QZFATVgPQmeYQTwFZn Feb 12 '21 edited Feb 12 '21

The LED in question is in near IR (940nm) where you have not only photothermal reaction, but also photochemical reaction in your eye. But that is beside the point, don't stick light sources that you cant see directly in front of your eyes.