From evening drives to navigating a house or a park in the dark, there are so many situations where it'd be handy to slip on a simple pair of night-vision lenses and the world that's beyond human optical perception could be illuminated like never before. This vision could be a reality, with a…
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.