Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

Question abut 3X BE and G2 / G7 lens


New member
Aug 18, 2019
Hi all!

I understand that G2 lens has about twice the divergence of G7 lens, and that 3X BE will make the divergence 3x less. My question is, if a laser is equipped with G2 lens and 3X BE, will the divergence be the same or less than the divergence of only using G7 lens?

I really appreciate all replies!


Well-known member
LPF Site Supporter
Jan 29, 2014
Unless the focal length of the G7 lens is three times greater than the G2 lens, it won't be 3X less divergence. I think I know why you are asking this, I can't yet find the specified focal length of the G7 lens, not even on Sanwu's web site.

What amount of divergence is acceptable to you? Which diode? If you want low divergence, putting a BE in front of either of those lenses will reduce the divergence further, but a longer FL lens always wins in the divergence contest and from what I gather the G2 has the shortest FL of those two. Best of both worlds of those lenses is a G7 with a 3X BE, or higher amount of expansion. If you are considering the Sanwu "3 X" beam expander, it's reported to really be 3.3 X. Also, the new DTR G8 might have a longer FL than the G7, but there is a limit to how long the FL can be inside the small threaded mounts we use, if too long, the beam will get cut off or truncated inside the small barrel on the way out.

From what members are saying, the G8 appears to be the most favored lens for our pointers right now:

Edit: Did you see this thread? https://laserpointerforums.com/threads/sanwu-g2-vs-g7.97280
Last edited: