NavList:

Bill, you wrote:

"Point being, I seriously doubt the lasers you refer to meet the standards of
both monochromatic and collimated light. "

 

They're real lasers. They produce monochromatic, coherent light --no cheating on the terminology. All lasers have some beam spread, and you can counteract it, up to the diffraction limit, using a telescope. One can even buy devices specially made for this purpose for laboratory lasers. Here's one example:

You'll notice it's nothing but a telescope marketed differently.

 

By the way, while I was googling around, I found a site that sells several nice models of green lasers. They're fun for pointing out constellations and such. These lasers have visible beams at night. You can aim at Aldebaran and everyone around you will see a green line reaching right up to Aldebaran.

Nothing like this is needed for any sextant testing that I can think of, but I might have to buy one soon just for fun. :-)