Material opaque to IR but transparent to visible light

In summary: This material is also called Copper II sulfate. 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.
  • #1
refind
51
0
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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  • #2
What's wrong with glass with a blue filter on it?
 
  • #3
Thanks. What is the blue filter? What material is it, are there any links you can point me to? I appreciate it.
 
  • #4
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')?
 
  • #5
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.
 
  • #6
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:
  • #7
What range of IR?
 
  • #8

1. What is a material that is opaque to IR but transparent to visible light?

One example of a material that fits this description is glass. Glass is transparent to visible light, allowing it to pass through without obstruction, but it is opaque to infrared light, which is why greenhouses made of glass can trap heat inside.

2. How does a material become opaque to IR but transparent to visible light?

The transparency or opacity of a material to different wavelengths of light is determined by its molecular structure. If the molecules of a material are spaced in a way that allows visible light to pass through but blocks infrared light, the material will be opaque to IR but transparent to visible light.

3. What are some applications of materials that are opaque to IR but transparent to visible light?

Materials with this property are commonly used in thermal insulation and energy-efficient windows. They are also important in the production of solar panels, as they allow visible light to pass through and be converted to energy, while blocking the heat-generating IR light.

4. Can materials be transparent to both IR and visible light?

Yes, there are some materials that are transparent to both IR and visible light, such as certain types of plastic. These materials are often used in thermal imaging cameras, which detect heat signatures in the IR spectrum.

5. Are there any disadvantages to using materials that are opaque to IR but transparent to visible light?

One potential disadvantage is that these materials may allow too much visible light to pass through, resulting in excessive heat and glare. This can be mitigated by using coatings or tints to control the amount of visible light that is transmitted. Additionally, materials with this property may be more expensive to produce compared to traditional materials.

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