Beam expander or not?

[wby300]

I ask because I want to make a fixed laser on an engraver and am considering using a larger focal lens than the normal 6mm ones. would it be better to use a beam expander, or just use 2 focus lenses? The first would not focus tight, just use it bring the beam in and make it round. I want to use either the 9mm 3W 450 or the 16x 1W blu ray I have coming for this. I have purchased several of these: New GSI Lumonics Laser Scanning Galvo Mirror Linear Motion Scanner Motorized | eBay
This could be used to vary the focal plane of the beam.

Focusing and Collimating

 

[The Qube]

I think a normal focusing lens will do the job. A beam expander would be anyway to big for engraving.

 

[Bionic-Badger]

You only need an expander if you want good divergence -- at the cost of beam width -- over long distances. For an engraver, you'd just want to focus on the plane of interest.

 

[wby300]

You guys are right, I guess I was thinking more about cutting than engraving which isn't going to happen with the powers this will be at.