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"Infra-red" covers a bunch of wavelengths. 'Near Infra-red' is very close to visible light, and is what's used by remote controls and picked up by cell phone ca

"Infra-red" covers a bunch of wavelengths. 'Near Infra-red' is very close to visible light, and is what's used by remote controls and picked up by cell phone camera sensors. It's around the 0.75–1.4 μm range. On the other hand, thermal cameras are sensitive to 'Long-wavelength infrared' which is around 8–15 μm wavelength. Marketers of things like CCTV cameras love to sow confusion about these things, as NIR-sensitive cameras are extremely cheap while thermal cameras are comparatively expensive. Humans are not sensitive to NIR because for the vast majority of human existence, any time there was NIR light there was also an abundance of normal visible light, due to a little thing called "the sun"

what-the-grump 2y ago
Idk, I think it would be nice to have non shit night vision.
- LeifCarrotson 2y ago
  Non-shit night vision, the kind where warm things glow at night, requires LWIR sensors that are at a temperature lower than the warm thing (otherwise the sensor itself glows). NIR sensitivity does not improve night vision. That mostly requires a "tapetum lucidum" or reflective layer, more rods than cones (less helpful when you want to see colors in daylight) or just larger, more biologically expensive and vulnerable eyes than necessary.
  - dTal 2y ago
    > NIR sensitivity does not improve night vision Your comment and its grandparent are both excellent, but I would like to nitpick a bit here. Technically, NIR sensitivity does improve night vision through the simple mechanism of "detect more wavelengths = detect more total light". It's not thermal imaging, but it is the reason that CCTV cameras often mechanically move their IR filter out of the way when the light falls below some threshold - at that point, sensitivity is more important than color fidelity, so they accept all the light they can get, even nonvisible. Of course this is also often coupled with NIR illumination LEDs.

what-the-grump 2y ago

Idk, I think it would be nice to have non shit night vision.

LeifCarrotson 2y ago
Non-shit night vision, the kind where warm things glow at night, requires LWIR sensors that are at a temperature lower than the warm thing (otherwise the sensor itself glows). NIR sensitivity does not improve night vision. That mostly requires a "tapetum lucidum" or reflective layer, more rods than cones (less helpful when you want to see colors in daylight) or just larger, more biologically expensive and vulnerable eyes than necessary.
- dTal 2y ago
  > NIR sensitivity does not improve night vision Your comment and its grandparent are both excellent, but I would like to nitpick a bit here. Technically, NIR sensitivity does improve night vision through the simple mechanism of "detect more wavelengths = detect more total light". It's not thermal imaging, but it is the reason that CCTV cameras often mechanically move their IR filter out of the way when the light falls below some threshold - at that point, sensitivity is more important than color fidelity, so they accept all the light they can get, even nonvisible. Of course this is also often coupled with NIR illumination LEDs.