Visible light gas lasers usually have excellent divergence. I have an argon and the beam is pencil-lead thin for a long, long ways. I don't have any idea of the actual divergence number or how to figure it out.
But I do know that my CO2 has the worst divergence - a nickel-sized beam (or burn mark - that's about the only way you can tell, of course) at about 15 feet or so. Any further than that and it won't burn a thing!