Beam expanders on a Co2 galvo laser

Hi guys,

I’m currently in the market for a CO2 galvo, probably a 60w Chinese build machine. Now I’ve read and seen my fair share of suggestions when it comes to this laser, DAVI seems to be the most used source (as far as I can tell) and a beam expander is also recommended with a 20mm head for a smaller dot size.

Now I’ve been quoted a few machines already, but some Chinese suppliers seem to contradict a few things:

One of the Chinese suppliers suggests a 8x beam expander with a 20mm RC2808 scanner, however another is saying that a 6x beam expander is the better option because the 8x beam expander could cause the workarea to be less big. So for instance a 300mm work area would actually only be a 250-260mm workarea because of some beam dispersion (as he mentions it).

Now I’m not expert, and I really just want the best (Chinese build) laser I can buy. Are there any people here that could share there two cents on 8x beam expanders vs 6x beam expanders? Even sharing a complete setup you’re happy with would definitely help, I’m kind of losing overview right now :sweat_smile:

I’m not working with beam expander hardware, but I know a bit about them.

Is a good read, that applies to all optics… being it’s from Edmund Scientific in the optics category.

If the maximum input beam size is 20mm and your beam is 5mm in diameter, if you use an 8 times expander, it should result in a 8 * 5mm or 40mm beam size that is twice the maximum diameter of the allowable beam input to your 20mm galvo head… You would have to know the source beam diameter to make sense of this.

If the maximum input is 20mm then you’re cutting off part of the beam and it’s energy…

Doesn’t seem reasonable to me… but you might look at the math and see how it really relates.

Russ Sadler has messed with these and I’d suggest you spend some time with his videos. I don’t think he uses a galvo head, but he’s an engineer and I believe his work is very informative.

Let us know what conclusions you reach…

Good luck