638nm divergence is terrrible

I recently got a 300mW 638nm laser (the lazerer rifle) from a member on the forum and the divergence is terrible I have not measured it but it is probably a yard wide 100-200 feet away. So I was wondering if I could somehow put a lens in one of the attachments (like the arctic it has thingermagigs that screw on the end to produce effects such as a starry sky affect) I already took the lens out of one but could I put something in that could help the divergence and (if possible) get a better dot? Or would it be easier/cheaper to get a 500mW (or more if possible) 650nm diode and just rebuild the laser? :thanks:

This diode (like our 445's) is a multimode diode, it's meant to have a square beam. (as a consequence the divergence is also bad) There are correction optics for these however they're either A) very costly, B) not-as-costly but produce a square beam. Not to mention the size of these...

You won't do any better with a 500mW 638nm diode.

You can replace the diode inside this, however you'll need to change the driver out... which may just end up being just as costly as buying a new laser.

I went through the same thing when I got a 638.
Then I saw this in small print uner the add after I got it.

*Due to the fast axis divergence of 638nm laser diode. The dot of this laser will be focused as slightly line shape rather than perfect dot. A small shadow appeared next to the dot is normal phenomenon and will not affect the using

Yep the high power 635 diodes are disappointing. We've all been though it. If you truly want a nice dot @ ~635 you are going to have to grab a low power single mode build.

I really like the host it sucks that it lazes terribly lol.

p.s. How much do you think it would cost to put a 300mW 532nm module in it?

ZRaffleticket said:

This diode (like our 445's) is a multimode diode, it's meant to have a square beam. (as a consequence the divergence is also bad) There are correction optics for these however they're either A) very costly, B) not-as-costly but produce a square beam. Not to mention the size of these...

You won't do any better with a 500mW 638nm diode.

You can replace the diode inside this, however you'll need to change the driver out... which may just end up being just as costly as buying a new laser.

Click to expand...

For shitz n giggles...where might one purchase these correction optics? I would like to avoid the infamous dr. Lava. Have not once seen him post on this forum since I started, and I heard he stopped shipping orders. For my build, I would like to keep it as linear as possible. And possibly have it fit inside the axiz set up..

I have yet to see any bean correction optics that will work inside an aixiz lens space. There are several lenses floating around that are rumored to be better with divergence but aside from a too-large-for-pointer optics setup(IMHO) you will never get a dot like a single mode gives at least as far as I have seen and I have looked for the same reasons. Unless of course you feel like making a host from scratch to house the required optics.

AnthonT found a lens that is slightly better for divergence but sadly its for 405nm and 445nm. It is here if you are interested for any reason.

BTW I just finished a 500mW 638nm Mitsu build and the output is so high that even though the dot is... not so much a dot, it still makes a quite visible beam midair at night. If you build with a 300mW you don't want to overpower it or you will get wavelength shift so even if you gain output power it may actually look visibly dimmer and you may want to consider investing in a 500mW so you don't have to drive it as hard.

PM Lazeerer he has the best lower divergence lens I have seen yet for the high power 635's.

I think I'm going to have to see what this lens is all about myself

The power loss is well worth the better beam specs imo. I can't see myself using anything else for 635nm... and currently don't.