Crooked beam. :/

[ColdWelder]

So i put a 20mw green module in a c6 host to test out the modifications i made to the host. Almost immediately i noticed that the beam is leaving the module at an angle. :huh: But upon inspection of the lens housing and lens, I can't seem to figure out why.. Any help would be much appreciated.

 

[kiyoukan]

did you take apart the unit?
Was it like that before?
A crystal or lens could have been moved or you over tightened and now they are no longer aligned.

 

[JLSE]

There is a small expander lens which the 532 beam passes before the light
gets to the outer lens which is the one you can see. If the internal expander
was not glued in properly, or has shifted, it puts an angle on the beam which
will translate out of the collimator. You will see this commonly in low cost lasers.

It is possible to correct, but can be tricky. You also need a set of 808nm protection
goggles to perform the repair..

To straighten the beam on yours will be a matter of a fraction of a millimeter of
movement on the expander.

You will need a steady hand, and some 5min epoxy, or you can just live with it..

*EDIT*

Here is a pic that should give you an idea. Think of the second lens as the same
as the lens you can see on your module.. Before that is the expander. The raw beam
leaving the crystal diverges too fast, so it is first passed through an expander, if the
expander is not hit in the center the beam hits the second on an angle.

With your module, the optics must be all centered to get a straight beam, as
they are housed in a tube.. Hope this helps :beer:

 

[LaZeRz]

Yo wannaburn, whats the power of that 532 rig?

I don't have ~900 dollars to spend on a 1w green and im thinking of going DIY if I can source the crystals/diode

 

[ColdWelder]

Thanks guys! @kiyoukan, no I didn't take it apart, but it IS from dealextreme. I bypassed the switch and mounted my own spring. I'm not the best with a soldering iron and it is possible that i something could have wiggled around i suppose. But something tells me that it came this way. @wannaburn, Thanks a lot for the explanation. So, is the light already in 'beam' form when it hits the outer collimating lens? I assumed that behind the lens was a standard unfocused profile, so I immediately thought to blame the collimation lens. I imagine having a quirky 10dollar module is better than wasting a lot of time on it. It was a good deal, but i don't think I will order from them again...

 

[JLSE]

Yo wannaburn, whats the power of that 532 rig?

I don't have ~900 dollars to spend on a 1w green and im thinking of going DIY if I can source the crystals/diode

Thats a pic of an 808 test jig I made.. I use the same crystal set to test surplus
808 diodes to be sure they are suitable for DPSS.. In that pic, its only <200mW.
Its possible to squeeze 300mW out of that crystal set, but doubt much more.

@wannaburn, Thanks a lot for the explanation. So, is the light already in 'beam' form when it hits the outer collimating lens? I assumed that behind the lens was a standard unfocused profile, so I immediately thought to blame the collimation lens. I imagine having a quirky 10dollar module is better than wasting a lot of time on it. It was a good deal, but i don't think I will order from them again...

It doesnt really matter where you get modules from unless they claim some
sort of QC... Its common when ordering low cost dpss made in China.

If you think a 532nm beam is thin, you should see it coming straight from
the crystals.. Its about 1/10th the size of the thinnest 532 you've ever seen.
The problem is in that state, they diverge worse than a 445, but are nice and
round.

To clean up the divergence, the additional optics are used.. The first lens
makes the beam diverge even more, and the second optic brings it back
to parallel, reducing the divergence / slowing it. In turn you get a more workable
beam...

The problem that arises is fast production, and lack of care in assembly
lands some modules and even full assembled lasers with a crooked beam
as you have in yours.. Luck of the draw, that all.

 

[Joe Mo]

What kind of angle do you think were talking here? I think alot of lasers have slightly off centered beams.

 

[cheech226]

does the beam exit the module or the host off center? i've put a few 532 mods in hosts and ofttimes the setscrew will cause the beam to exit the host at an angle.

edit: and i've found the expanding lens is often not placed correctly. my firedragon needed this lens adjusted as did a few modules i've purchased. i had a link to buy these lenses, i'll look it up