450nm 50000mw laser lens size

[JamesC1117]

Okay so I'm still relatively new to the hobby of lasers don't know how to build them or anything yet. I bought this laser pointer from AliExpress and the lens that was in it quickly burned out I bought a lens on Amazon and it didn't quite fit the bean comes out sideways as if it was slanted. I've had no luck getting back in contact with the seller to get the size so I'm reaching out to you guys hoping someone will know exactly what I need. There are pictures posted of the laser and the lens I bought from Amazon that made the beam come out at an angle as seen in one of the pictures

 

[julianthedragon]

Did the beam come out slanted with the old lens, before it burned out or just because of the new lens? Beam alignment can be hard to get right and you see that often in cheaper models and custom builds. Btw the laser is probably 5000mw at the most not 50000

 

[JamesC1117]

No it was straight before and the new lens seems to be loosely fitted to the housing which is probably the cause of the slanted beam

 

[JamesC1117]

The original lens was plastic and the laser melted through it.

 

[Sowee7]

The original lens was plastic and the laser melted through it.

but that shouldnt happen if the plastic was clear, also the laser isnt 50,000mw, its only 1,500mw

 

[paul1598419]

Those acrylic lenses will melt easily even at 1 watt, so that was absolutely going to happen with this laser. You should be able to get a tight fitting glass lens on DTR's site.

 

[JamesC1117]

The problem is I don't know what size lens I need for it and I don't really feel like buying 10 different lenses to find the one that will fit properly.

 

[JamesC1117]

And the lens that's in it now has burns on it from just the few times I have had to use it to show someone what's going on with it. So wrong lense means glass or not it will burn.

 

[JamesC1117]

As for it being only 1,500mw doesn't really matter to me fact is I am only worried about the lens right this minute

 

[JamesC1117]

Idk if it's M9x.8, M9x.5, ECT

 

[JamesC1117]

I guess the easiest way to put this without coming off like an jerk is I don't need a discussion on whether the milliwatts were exact or whether the acrylic lens should have burnt out or not. The only thing I'm asking for and that nobody thus far has been able to provide is what size lens I need to purchase because the lens that I bought didn't work. I don't feel like spending money on stuff that is not going to work. Now if need be if nobody can tell me I'll go buy lens after lens after lens after lens after lens after a lens until I find the one that fits. But as it stands everybody was come here is just wasted my time except for the guy that recommended DTR's site because I will go ahead and buy a lens from there because they only sell lens that are M9x.5mm and maybe that will be the lens that I need. I guess what I'm saying here is I didn't need 15 different conversations I needed one.

 

[WizardG]

You're buying a lens in a barrel if you're talking thread pitch. Why not replace just your melted lens? Measure the OD of your original lens then measure it's focal length and get an appropriate replacement to install in the original barrel.

 

[JamesC1117]

Firstly I don't know where the original lens is I never threw it out but can't find it anywhere now. Secondly I don't know what you just suggested

 

[JamesC1117]

Not that I haven't thought about measuring it myself but I don't have a micrometer. That part I didn't understand the focal length of measuring I'm not sure how that's done

 

[WizardG]

Use the lens to focus an image of an overhead lamp or nearby window on a piece of paper or some other 'screen'. Best focus distance is a good approximation for the focal length of the lens.

 

[RA_pierce]

Any of the lenses sold on DTR's shop will work.
The thread specification for the brass housing for the lens is M9x0.5.
The glass lens itself is often 6.33 mm diameter but this dimension varies as there are many clones that vary in quality and specification.
The current favorite lens is the G8 lens as it incurs minimal losses and since it has a longer focal length than the G2 lenses, it provides lower divergence.
The focal length is not especially important for the fitment of the lens in your laser. Since the lens housing is threaded, you can adjust the distance of the lens to the laser diode by screwing it in/out to the correct focal distance.
If the fit of the lens is too loose (which will result in a de-centered beam as you noticed) you can apply a thin layer of teflon tape (plumber's thread sealing tape) to the threads of the lens housing before inserting it. This will take up some of the slack in the threads and prevent it from wobbling around.

Good luck.

I guess the easiest way to put this without coming off like an jerk is I don't need a discussion on whether the milliwatts were exact or whether the acrylic lens should have burnt out or not. The only thing I'm asking for and that nobody thus far has been able to provide is what size lens I need to purchase because the lens that I bought didn't work. I don't feel like spending money on stuff that is not going to work. Now if need be if nobody can tell me I'll go buy lens after lens after lens after lens after lens after a lens until I find the one that fits. But as it stands everybody was come here is just wasted my time except for the guy that recommended DTR's site because I will go ahead and buy a lens from there because they only sell lens that are M9x.5mm and maybe that will be the lens that I need. I guess what I'm saying here is I didn't need 15 different conversations I needed one.

The crowd here is easily side-tracked and has a tendency to split hairs.