EEVblog Electronics Community Forum
Products => Thermal Imaging => Topic started by: aargee on June 11, 2023, 11:33:45 am
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Interesting article.
https://techxplore.com/news/2023-06-weve-lens-thermal-cameras-spy.html (https://techxplore.com/news/2023-06-weve-lens-thermal-cameras-spy.html)
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Here is the actual paper https://onlinelibrary.wiley.com/doi/10.1002/adom.202300058
And I fail to see it's significance. I haven't read all of it, but skimmed through it a week ago when some news article put this front of me.
It does sound to me like they figured out that some plastics are transmissive in the LWIR spectrum and the refractive index is different than air so it can be used as a lens. It's not news to me and we have had several forum posts on this subforum that explore similar ideas. Even fresnel lenses were shown to be kinda working.
One of their takes is that it's optically opaque and could therefore be used as a LWIR only window, to hide cameras. And that's already the case with several other materials. And it doesn't seem to be optically any good.
All their experiments use this as a supplemental lens Infront of the Ge lens. Low cost lenses for thermal cameras have been in use for a while, for example moulded silicon.
Please someone help me understand how this work introduces something novel. It just looks like more sophisticated than the "experiments" done on this forum.
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The significance is that they are loading plastics with sulphur to get a reasonable, numerically real, IR refractive index in 3-5µm.
ZnS is a common 3-5µm optical material in crystal form.
LWIR transmission is not 'high' to me at 9% even if it is a bit better than their previous attempts.
A window of 0.8mm is not strong either.
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Yeah I also stopped reading once I saw 9% being touted as good