I've got 2 lasers in the shop, both fairly accurate. The small one with strippers uses a magnetic switch of some sort, that just has to have a sliver if steel interred to the right point. The big laser uses standard lever switches, with rollers on them, to zero x and y. It's pretty good, good enough that if the power goes out mid job, It can boot up, zero, and continue. But it also uses servos.
I would be worried about optics in a shop embodiment. Most cnc machines h have some sort of magnetic switching to do limits and such, so that might be your best bet.