Help with my 300mW 405nm Focus Lens

Hi Guys,

Not sure if this is the right place to put the post; please move it if there is somewhere else more appropriate.

I bought these two lasers. The Violet has trouble focusing at a distance more than 6 -8 metres. I've tried all extremes of the focus, even taking it off - so I see the "focus curve" in my mind and understand what needs to happen. I think that the lens needs to get closer to the laser output (the beam starts thick, and then as I tighten the lens it goes thinner and thinner, but never thinner enough). I mean, I can focus all its power at close range (0.5 - 2 metres) without too much trouble, but when it comes to shining it in the sky next to my Greenie - its like a blurry blob, it really opens up wide. Here are some photos of the laser, detached - and close ups of the lens so you experienced folk can see how this one has been put together.



I'm not sure if I can take it any closer. As you can see the lens itself is threaded, and it already sits very close to the little knobbly flange thing. Does mm of movement make a big difference? Maybe I can shift the lens just the smallest amount - without the glass touching the nossle? What do you guys think?

I have seen a member sand down the part to get it closer to the laser diode. I'm sorry I don't remember who. Protect the lens.

Good luck,

~ LB

Well you should try to unscrew the lens from the lens cap a little so it can get closer to the laser.

Lazerbeak said:

I have seen a member sand down the part to get it closer to the laser diode. I'm sorry I don't remember who. Protect the lens.

Good luck,

~ LB

Click to expand...

That looks quite tricky. I've looked at the cap closely now - and measured it. It is "stopping" both from the outside ring hitting the lip on the host, and also because the inside is hitting the tip (if that makes sense). Wow, I need to upgrade my vocabulary! How to explain! lol

norbyx said:

Well you should try to unscrew the lens from the lens cap a little so it can get closer to the laser.

Click to expand...

Well I was hoping this may be a solution - upon looking inside the FRONT end of the lens cap - I saw two little notches, which appear to be designed so that you can insert a small flathead screwdriver, and rotate the lens inside the cap. Upon trying, I was unable to turn the lens inside the cap. I investigated further and established that the lens part itself (have a look in my pictures) is threaded, and is the part that "holds" the cap onto the host. It therefore cannot make sense that it is rotatable - they must have glued it into place?

Hrm.... I'm stuck again.

Try heating it up, therfore you will cause the glue to soften and then try turning it

Laik said:

Try heating it up, therfore you will cause the glue to soften and then try turning it

Click to expand...

That sounds like a fair call. I'm really nervous - not much of a naturally minded mechanic, and these are my first lasers. Might be a dumb question but - what should I use to heat it? What other things should I be concerned about? I don't know how to treat the lens. I'm guessing I have to focus on keeping it level and straight - unless it is sitting on threads. Any clues?

You could use a hair dryerto heat it. Be careful not to melt the lens if it is acrylic (i doub't it would be), i say it would be threaded as well. Don't scratch or smudge the lens either. That's all the information i can offer you