this post was submitted on 05 Jun 2024
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"From evening drives" Bad enough dealing with modern headlights with normal eyes
Do modern headlights emit IR? I don't think so. Which means these IR amplifiers wouldn't change the intensity of headlights.
IR is heat, so headlights produce a a lot of IR. Laser headlights emit less IR with the visible light, but radiate heat.
Well, IR isn't heat, but it's associated with it. And since laser and LED lights heat up a little bit, yes, they of course produce a miniscule amount of IR. But it's pretty much negligible in comparison to their visible spectrum emissions. If you're already being blinded by the visible range of the laser, the IR part isn't gonna do much.
You asked if headlights emit IR because you didn't think they do, they emit IR.
Fair enough, I was being too vague with my statement. I was implying that they don't emit much IR, as all bodies above 0 Kelvin do emit it. And LED/laser headlights almost don't, in comparison to xenon and stuff. I looked up some Xe emission graphs and some even straight up show the peak in near-IR, while laser/LED starts flatting out way before NIR.
Touché
Now that I've read my own comment, I see that it came off harsher then I intended it to. Interpret it literally and not like a sarcastic statement.
Btw, just occurred to me that these would probably not work in a car at all, because regular glass is usually opaque to IR.
I'm almost 100% positive that this is not correct, because I've been driven around by someone wearing PVS-14 NODs with no headlights, on dirt roads, in a commercial van. (Edit - most red dot sights also work very well with NODs, and those have one or two layers of glass, depending on which type of system it is. The sights that don't work well usually can't dim the dot enough to avoid massive bloom.) Glass is mostly opaque to thermal though, and a lot of glass significantly reduces UV.
I can't say I have any experience with PVS-14 or any Night Optical Devices, but from what I see online, it amplifies certain visible spectrum as well as near-IR. It doesn't seem to rely on IR much. And red dot sights aren't even IR are they? At least not entirely, cause you can see them with the naked eye.
Regarding glass being opaque to IR, apparently, it depends on the type of glass. I just remembered it from a Vsauce video (IIRC) where it was demonstrated to be opaque. But since term IR is vague and doesn't have super defined borders, and there are different types of glass, yeah, it's not a certain statement.
Okay, so you're talking about the IR that most people would refer to as thermal, rather than the IR that's technically NIR, and is used in most image intensification. My mistake; as you say, these things get slippery because most of the time people aren't talking about specific wavelengths and frequencies.
Yes, IR-as-in-thermal is going to be stopped by most glass. IR-as-in-NIR-for-NODs is not. The IR lasers and weapon lights that show up very well with NODs are definitely not visible to the naked human eye, so they're outside of the visible light spectrum, and get generally labeled as IR, even if they're outside of the spectrum of IR that's used by most thermal optics. (It would be interesting to see if a Steiner DBAL could illuminate an area that had low IR for a FLIR camera.) And yes, for that, a red dot sight will work, because it will be set to very, very dim; too dim to be seen by the naked eye.
I'm sorry if I made the false impression that I know what I'm talking about. I'm just discussing and learning as I go. But I went back to the article and looked for the specific figures, and you were right, they are amplifying 1550-nm wavelength, which is NIR. And average glass is usually opaque to wavelength at around 2500nm, so it shouldn't get blocked. At least not much.
The material captures visible light too, so headlights would be brighter, but I wonder if there's a way to reduce the contrast by either filtering out some wavelengths (like driving glasses) or the material simply not boosting it's output past a certain level?
If I understood correctly, it captures visible light to use it for the amplification of the IR spectrum.
The article says:
From that, I think it's suggesting it needs a separate beam of photons to amplify the signal, much like a transistor needs a supply current to amplify the signal it gets.
They also say:
Which sounds like it produces an image showing both the IR and visible spectrum in the visible range.
Mind you, re-readind it, most of the article just talks about IR, so I'm not certain what it's actually doing. It could just be transparent to the visible spectrum. It wouldn't be much good for driving if it did that though, the windscreen blocks a lot of IR and you'd need IR headlights!
Yeah, it's absolutely clear that nothing is clear about its operation.