Stupid Optics Question - Laser line divergence

I have a stupid question, if using a plano-convex cylinder lens or a glass rod with a laser beam which has been focused to infinity (to produce a thin wide line), what is the divergence of the line?

Some might look at this question as invalid; how is divergence related to a laser line which spreads into a thin plane many degrees wide? I mean in the opposite plane, or the thickness of the line. What determines how much thicker it gets as the line travels forward?

My assumption is the thickness of the line diverges at the same rate as the beam had prior to shooting into the line lens, correct? Yes, no? More info?

EDIT:

One more maybe not so stupid question, I want to bore a hole through a PBS cube, anyone know where I can send a cube to get it done? Needs to be accurate without damaging the cube. This would be to coaxially combine three beams, the beam going through the hole a much smaller diameter beam than the other two going through and being combined, of course. I'd rather have a cube which simply has an absence of a polarised layer in a very small area in the center, but haven't seen anything like that.