I’m confused, how would she have seen the IR beam? Wouldn’t she be seeing some other effect, or was this literally so powerful it was in that realm of two-photon absorption

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ashdksnndck 5 hours ago | parent [-]

A beam of non-visible radiation can cause secondary radiation in various ways. Hopefully it’s the dust in the air fluorescing or being heated. Black-body radiation from some part of your eye would be concerning.

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godelski 2 hours ago | parent [-]

Additionally human eyes are sensitive to near infrared. Go look at a TV remote in a really dark place. Check with your phone because your phone can see it. If you can't then check with the nearest child, they'll tell you.

You lose sensitivity to this bandwidth as you get older. But if it's bright enough you'll see it. It's not like there's a hard cutoff in your eyes detection, it decays and you're very insensitive to big bandwidth, but not necessarily blind to them

	▲	kulahan 2 hours ago \| parent [-]
		Now that you mention it, I do remember occasionally being able to pick up on a faint red light in the remote control back when I was younger. It was easier to see with a phone’s camera I think?