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0 pointshollerith1y ago0 comments

But the OP is about near-infrared (NIR) light. Sensitive instruments for detecting NIR can only detect objects hotter than 440 deg F (according to an LLM I just consulted) and even then longer wavelengths are the preferred wavelengths for detection: NIR doesn't start becoming the preferred wavelength till the object gets up to at least 800 deg F.

The sun emits tons of NIR, so if this tech has a practical application, I'm guessing it is in detecting objects outdoors during the daytime that look distinctive in NIR and do not look distinctive in visible light, e.g., maybe military hardware covered by fabric or camouflage netting.

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potato37328421y ago· 1 in thread

>NIR doesn't start becoming the preferred wavelength till the object gets up to at least 800 deg F.

My understanding is that due to the relative bell curve of emitted wavelengths a hot object should still look "funny" in the same way that a cherry red piece of iron still looks like iron, just different. Is that not true for NIR?

hollerithOP1y ago

I can't understand the question.

But the spectrum of a hot object is not a bell curve. Specifically, there is a sharp cut-off such that there are basically no photons with wavelength below the cut-off. An incandescent light bulb of the type people used in houses in the 1980s and before for example produces a very small amount of UVA, but basically no UVB, UVC, x-rays or lower wavelengths.

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