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I have a situation in which I need to use a thermal camera in a rain enviroment, the camera is mounted on a gymbal and can rotate 360 degrees, so I tought it may be an option to build a dome in order to separate it from the rain. I tested the absorption of a couple materials without much success. Glass, polycarbonate, and acrylic do not allow IR. I tried with some bags that I beleive may be made out of nylon with sucess, but this material may not be rigid enough to build a dome. What do you suggest? Perfect thermal values are not necesary in the proyect, I just need to be able to identify people. enter image description here

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2 Answers 2

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Intrinsic silicon transmits infrared. It may be expensive, though, when obtained from a supplier.

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  • $\begingroup$ Not available as a dome. A piece of a wafer might be suitable as a window, I can test that tomorrow. $\endgroup$
    – user137289
    Commented Feb 19, 2019 at 19:09
  • $\begingroup$ Pieter, were you able to test it? A wafer used as a window may be a possible solution. $\endgroup$ Commented Feb 22, 2019 at 16:26
  • $\begingroup$ I tested it a few years ago. The camera showed my face straight through a wafer. $\endgroup$
    – my2cts
    Commented Feb 22, 2019 at 18:23
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I think your issue is with reflection.

I've used thermal imaging cameras a lot for work (and also for fun), and I find that most glass and other shiny / low-emissivity surfaces reflects infrared, And I can see my own thermal image when I aim the camera at them.

Obviously glass (at least certain if not most kinds) allow infrared to pass through, the lenses for infrared cameras are made of glass, and the reason that modern energy-efficient windows have an invisible 'low-e' (low-emissivity) coating is because otherwise they allow infrared to pass through easily.

The purpose of that coating is to reduce the transmission of infrared either from the exterior (sunlight) to keep the inside cooler, and/or reduce transmission of infrared from the inside (from interior surfaces and especially from your body) to help keep the inside warmer (and to avoid a cold sensation while standing next to the window).

I digress but my point is, ordinary glass does allow infrared to pass through, and I'm no expert but I suspect that many other transparent materials do as well. But you would need a material that has very low infrared reflection, especially on the inside surface (low reflection on both sides is ideal, but while reflection on the outside would reduce the sensitivity of the instrument, it's reflection on the inside that really interferes and shows false images).

I know this is an old question, but hopefully this is helpful to someone!

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