I think the best way to tame the beam with an asperic lens with a short focus length like the one from Larry DFW (LPF) and then 1 cylindrical lens to tame the x-as (fast axis)
Andythemechanic said the otherway arround, here,s the message he send me:
actually it should be the other way round: The invariance of the beam parameter product dictates that the longer the focal length, and therefore spot diameter, the smaller the divergence. I think the difference between this lens and other lenses with higher focal length, is that this one is aspheric and eliminates spherical aberations, while other lenses are often simple spherical ones that introduce aberations and worsen the beam. So going to high focal length with aspheric lenses should be the way to reduce divergence. Of course you have to retain a high NA of roughly 0.5 to catch the whole beam on the fast axis.
The lens that andy used was:
Thorlabs C610TM-A f = 4.0mm 0.60NA Geltech Mounted Asferische Lens
I would love to try these:
http://www.thorlabs.de/thorProduct.c...mber=C660TME-A
Fl= 2.97 NA = 0.60
Larry,s lens is simelar to the C660TME-A and a lot cheaper. I will try the on fro larry in my 4 setup next week