Summary

This is a simple device for checking the centring of an inexpensive laser collimator.

Essentially, it has 4 rounded posts on which the laser collimator rests. By holding the base still on a table and watching the laser on a far wall as the collimator is slowly rotated about its axis - you can see if it's good or bad. It's good if the dot doesn't move about much, and bad if it traces a large arc across the wall.

There's no point aligning a telescope up with a duff collimator...