I am purchasing a Sanwu 488nm pocket laser and I wanted to add a G2 and G7 lens, but there are 7mm and 9mm options on the site and I don't know which size to get? I checked the product specs and can't seem to find an answer.
That is the length of the lens, not the width. Either will fit, though since the G2 is a shorter focal length you'd probably have an easier time with the longer option.
That said, I don't recommend changing out the lenses on the pocket 488 unless the original built in lens gets damaged. I could list off a multitude of reasons, but the bottom line is that you won't notice a positive change from switching it out.
Good to know, I'm new to all of this and this will be my first higher powered laser. I saw there is a only 70% throughput on the stock lens and since they're cheapish I thought I would give the other two options a try. I don't care to burn anything with it and I want a thicker/more visible beam if possible. I may just hold off on buying any lenses then.
Yeah true while it is 70-80% on the 3E, the G2 is closer to 90-95%, so let's say at best a 25% increase, or +15mW. Say a keychain pet toy laser you buy from a vending machine is 5mW, that would be an increase equivalent to three of those. Not all that much power difference. Brightness wise, you'd be lucky to notice a 1.25x increase side by side.
Also the main reason is this... their built in lens has some silicone caked around it to help keep the lens still during normal use. Normally in the hobby we have springs to do this, but their host assemblies don't really fit well with them. The new lenses wouldn't have that, so you'd find yourself needing to adjust the focus more than you'd expect. Speaking from experience unfortunately...