Can I tell the Lens material by it's reflection color?

[sam1275]

Hello.
I just noticed the reflection color of different thermal camera lens are different, even if the scene is white, the Flir ix is purple, thermal eye is original color, and Indigo Alpha id yellow.
Does this cause of different lens material? Can I tell the Lens material by it's reflection color?
Thanks

[T3sl4co1l]

https://www.google.com/search?q=zinc+selenide

That's the yellow stuff.  Black to silver would most likely be germanium, but an interference color like purple suggests an antireflective coating.  Coatings can make most any color, so aren't indicative of the underlying material.

Tim

[cvanc]

Coatings can make most any color, so aren't indicative of the underlying material.

^^^This.^^^

[sam1275]

Thank you!