Split beam coming out of laser module

[blowfly]

My 640nm 400mw laserwave started doing something weird after the last rebuild of my projector. The red beam is split into two dots.

With the module shining directly on the wall, the two dots are vertically stacked one on top of the other. This can be seen clearly at 10% intensity. At full intensity, there is a horizontal ghost line as well as some crud projected around in a circular shape.


Going through the mirrors and galvos, the dots are horizontally side by side. This results in a double line for any vertical edge.



I tried cleaning the aperture outside the module with acetone and a swab. It looks like there is some crud on the inside of the glass. It almost looks like melted glue. Could this be the cause? The double dots are so distinct, equal brightness as far as I can see, so I'm wondering if there is some other problem.


This just started happening. I took all the components off the optical board to drill some more holes. Should I try opening the laser module and cleaning out the optics?

Thanks for any suggestions!
Mike

[MisterWilling]

The unit most likely uses two diodes that are knifed edged. It seems one has come out of alignment. Does the separation get worse with a longer distance? The only way to fix that would be adjust the mirror mount inside the module. If its under warranty I'm almost sure that would void the warranty. So check on your warranty status before you open it up. I'm also not sure how the mirrors are adjustable inside but I would assume they are.

[blowfly]

Yeah I'm pretty sure the divergence increases over longer distances. I couldn't get good pictures of it with the projector close to the wall, but far from the wall it is much more noticeable.

Thanks for the quick reply. I'll check on the warranty status.

Mike

[Stuka]

Same thing happened with my 300mw unit -
the mirror / PBS cube got knocked out of alignment internally.

Fixable, but a bit of a PITA!

Be sure to check with your dealer concerning warranty before popping the case open!!

[norty303]

Ironically my 350mW Laserwave 640 has just started doing exactly the same thing! Dots stacked vertically.
I believe these are cubes so I guess it's gone out of alignment.

I'm emailing my dealer to see what they have to say about it.

[mophead]

Yeah, they are cubes, not knife edged.

My 300 did the same. If it's under warranty, send it back. Don't know where yours came from, but Marc took care of me.

[megaton]

Same thing here with my 350mw unit.
And the cube and the mirror inside are glued.
Not and easy fix or adjustment.
What happen Laser Wave?
BTW Just return from Warranty from China. Arrrrrrrg... (almost 4 weeks later).
And at Max modulation some times not work smooth.

[megaton]

Some thoughts:
Same thing was happen when I put up side down a quad module of reds.
I'm wondering if I tight to much the screws or bend the base plate?
Or the lenses move?
Or when they fix it,(change one dead diode) they don't realigned at all.
Any thoughts?

Thanks,
Eduardo

[blowfly]

Decided to take a crack at fixing the alignment problems myself. I'm not sure of the best way to go about it though. I can wiggle the bounce mirror (marked with a double red line below) and get the two red dots to align correctly on the wall. I'm not sure the best way to fix it though. Inside the module, everything is glued down. I took the screws out of the PBS holder but it's still held in tightly by the glue. It looks like the there was some tin foil under one side of the PBS cube used to align the beams when the module was assembled (green arrow below). It seems like it I should be able to insert more foil under the cube, but I don't know how to get the glue off yet. Any suggestions? Am I on the right track with the foil?



Thanks for any ideas guys,
Mike

[Phredy1]

My guess is the mirror is the problem and it shouldn't wiggle.

Can you somehow realign the mirror and then epoxy it in place?