Adjusting a collimator laser beam shape?

[dcnicholls]

Many of the laser collimators I've seen have beams that aren't circular, but quite elongated. While they're still usable for lining up a secondary mirror, a circular beam would be more aesthetically pleasing and a bit easier to line up in the ring on the primary mirror. I assume the oblong shape has to do with the laser emitter and the focussing lens(es) not being properly lined up.

Has anyone taken a laser diode unit to bits to line up the laser emitter and the lens? If you can dissolve the (green) glue used to lock the adjustment, is it easy to tweak?

[bojan]

No it is not so easy. To achieve this you need to use a bit more complicated optics (beam expander, circular baffle etc)
You can focus the beam to particular distance though, and it will be OK within certain range.
But by fiddling with this you are risking the alignement of the whole unit. I would leave it as it is, since it is only aestetic issue :-)