Pigtails and lasers

So, I've got a 4 W IR laser diode (fiber optic with no pigtail collimator) and I'm stumped. I've been looking around for a collimator that will fit it at Thor Labs thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=1340 and I've got two problems. 1) Can't find the right lenses with all the right properties for my laser, divergent angle and such. 2) NO idea how to install it. Any help here?

my laser: psplc.com/datasheets/jdsu/JU6300Series_041802.pdf

(also, I know I'm new, but when can I start to post links?

The easy way to do this is to know what is the core size of the fiber and realize that it is approximately the same as the spot size of a collimated beam of diameter D going through a lens of focal length F. So find some equations off of wikipedia or something that give you the spot size of a gaussian beam that was collimated and had a diameter of (what diameter do you want the beam to be) and was sent through a lens of focal length F, now solve for F since you know everything else.

Another way to do this is similar to above. You know that exactly at the output of the fiber it is equivalent to the spot of a beam formed by focusing a collimated laser with a lens. If you want to collimate the output you can just put a lens the same distance away from it as the focal length and you will get a collimated beam (probably not more than 1 cm away for a reasonable beam size).

Try that, if it doesnt make sense I can try to elaborate/simplify the explanation.

10 posts before you can post links.