Material opaque to IR but transparent to visible light

AI Thread Summary
A user seeks a polymer that is opaque to infrared light while remaining transparent to visible light, questioning the feasibility of such a material without resorting to metamaterials. Suggestions include using a blue filter or a hot mirror to achieve the desired effect, with a focus on making an area invisible to infrared cameras but visible to standard cameras. The discussion also mentions the potential use of Copper II sulfate on glass as a solution, despite concerns about its effectiveness and the resulting blue tint. Participants emphasize the importance of understanding the specific infrared range to be blocked and suggest testing with an infrared LED. The conversation highlights the challenges in finding suitable materials for this unique optical requirement.
refind
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Hi all,

I want to get some sort of polymer that is opaque to infrared (absorbs wavelengths above 700 nm very well) but transparent to visible light (does not absorb much light below 700 nm).

Does this even exist without being a meta material?
 
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What's wrong with glass with a blue filter on it?
 
Thanks. What is the blue filter? What material is it, are there any links you can point me to? I appreciate it.
 
refind said:
Hi all,

I want to get some sort of polymer that is opaque to infrared (absorbs wavelengths above 700 nm very well) but transparent to visible light (does not absorb much light below 700 nm).

Does this even exist without being a meta material?

Is there a reason you want it to absorb instead of reflect (google 'hot mirror')?
 
refind said:
What is the blue filter?

It is a light filter that is blue. If you Google "blue filter" there are 610 million hits.
 
Andy Resnick said:
Is there a reason you want it to absorb instead of reflect (google 'hot mirror')?

Hot mirror is a great suggestion. I just want to make an area invisible to an IR camera but visible to a normal camera.

By the way I was googling around and someone says to spray Copper II sulfate on a piece of glass and that will do the trick. I don't mind the blueish tint and I might give it a try. Does it sound like a bad idea?

Vanadium 50 said:
It is a light filter that is blue. If you Google "blue filter" there are 610 million hits.

I didn't know blue colored plastic/glass will necessarily absorb IR. Thought it would just absorb visible red. I'll give those a try too, got an infrared LED I could see with my phone camera to test it out.
 
Last edited:
What range of IR?
 

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