I've done this experiment several times, and once upon a time I could describe exactly what is shown - but that was a while ago. I need a refresher. Take two polarizing lenses (let's keep it simple - transverse polarization), lens A and B, turn them 90 degrees to each other, they will block all light. Now take a 3rd lens C and insert it between the A and B at a 45 degree angle. You will now be see to see through again. The light passing through the lens A gets polarized, but that polarizing can be over a range of 90 degrees - 45 to the left, 45 to the right. It's enough to block any light from passing through the lens B but the insertion of lens C causes another rotation of the polarization by another 45 degrees, such that some of it can now pass through lens B. That's a lousy description, but my question is this: is that rotation of polarization (either left or right, or both until it's measured) a quantum mechanical effect?