The past days I've been trying to understand how AutoFocus(AF) works on photographic cameras. There is a statement that says AF systems are polarisation sensitive. This means that they can only work with circularly polarized light.
Trying to understand why, I came accross this article which states that beam splitters are polarisation sensitive. Is this true?
I cannot think of a way that the reflection of a linearly polarised light would have any problem or why a reflected circular polarized light would be OK.