There are certain situations where a low cost laser can be used to do precision alignments.
These are:
1)Rough alignments where log spacer couplings or cardan shafts are used.
Accurately projecting shaft centerlines from existing machines to locate lay out anchor bolts.
2)Checking location of machine cases on multi-machine baseplates to eliminate bolt bound conditions.
3)Exelent application is cooling tower fan alignment with coupling spacer removed.

The laser can be a pointer pen or a laser level with a horizontal anvil. This can either be mounted to an existing shaft with wire ties or hose clamps. See attached diagrams. Diagrams show laser in 2 positions, not 2 lasers.