Material opaque to IR but transparent to visible light

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SUMMARY

The discussion centers on the search for a polymer that is opaque to infrared (IR) light while remaining transparent to visible light. Participants suggest alternatives such as blue filters and hot mirrors, which reflect IR instead of absorbing it. A specific suggestion includes using Copper II sulfate on glass to achieve the desired effect. The goal is to create a material that renders an area invisible to IR cameras while still being visible to standard cameras.

PREREQUISITES
  • Understanding of infrared (IR) light and its wavelength properties
  • Familiarity with optical filters, specifically blue filters
  • Knowledge of polymers and their optical properties
  • Basic principles of light reflection and absorption
NEXT STEPS
  • Research the properties of Copper II sulfate as an optical filter
  • Explore the concept and applications of hot mirrors in optics
  • Investigate the characteristics of polymers that are transparent to visible light but opaque to IR
  • Learn about the use of infrared LEDs for testing materials' IR absorption
USEFUL FOR

Material scientists, optical engineers, and anyone interested in developing materials for stealth applications or IR camouflage technologies.

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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