Help me please...

[ElektroFreak]

Regarding the possible mode-hopping:

Normally green DPSS lasers are designed to produce a beam that when projected on a surface produces one dot, which is brightest in the center and less intense as you move away from the center of the dot. When a laser mode-hops, it tends to form a beam that produces more than one spot, or a blob-like spot instead of the normal clean round spot. This will cause the lines from you projector to look like yours do. This is an internal problem with the laser, and the quickest solution is to replace it. Repairing a DPSS laser that is out of alignment is complex and is not recommended unless you're willing to do a LOT of reading and asking of questions..

Here's a couple of articles about laser modes and mode-hopping:

http://en.wikipedia.org/wiki/Transverse_mode

http://www.rp-photonics.com/mode_hopping.html

[Laserman532]

for the love of god...put a fucking shirt on...OHHHHH MY EYES!!!!!

it looks like a basic alignment problem to me, note big ass beam coming out the top of the projector.

mode hopping...NOT!!!! you guys way over complicate things...

[ElektroFreak]

^Well to be fair we did say it MIGHT be mode-hopping, which is a perfectly valid possibility.. The only way to know for sure is to check the beam profile before the beam reaches the optics path inside the scanner, or to work out the possibility through trial and error.

[slicklasers]

It looks as if the output optic on the laser itself is dirty to me..... My best guess is if you clean all the optics with optical grade acetone and a fresh q-tip every time you make a swipe across the mirrors or optics, it'll be fine, if not, the output optic on the laser probably needs to be re-aligned... I bet it got dropped or bumped, or set up on a stack of speakers and that probably is when the problem started...

[Doc]

Oh my good God. Moobs.

[mixedgas]

It looks as if the output optic on the laser itself is dirty to me..... My best guess is if you clean all the optics with optical grade acetone and a fresh q-tip every time you make a swipe across the mirrors or optics, it'll be fine, if not, the output optic on the laser probably needs to be re-aligned... I bet it got dropped or bumped, or set up on a stack of speakers and that probably is when the problem started...

I'm going with the Slickmeister on this one. Looks like dirt on the OC at first. Several things can cause that kind of mode pattern, but the major one is diffraction from dust. Clean the laser output optic, and then get us a shot of the expanded beam without the galvos in the path.

You want to do a single pass of the cleaning material and then discard it, with really good acetone or methanol with no water in it. one smooth wipe across the optics, that is it. Then prepare a new cotton swab or use a new piece of lens tissue. Do not "scrub" the optic in a little circle or anything like that.

Video:

http://www.coherent.com/Service/inde...page&PageID=40

You can, for small optics that are mounted in tight spaces, use a cotton tipped swab. Get the ones from a good pharmacy with wood sticks, known in english as throat swabs or sample swabs. The plastic or cardboard shaft ones have glue, and that is bad. Wood ones usually have no glue to hold the cotton to the shaft. The acetone or methanol can dissolve the glue and put it on the optic. Use a new swab or lens tissue for each pass.

Do not dip the swab back into the bottle, pour the acetone or methanol onto what you use for cleaning.

Then when your done, clean the galvo mirrors.



Who made your green laser? What model is it?

Steve

[LASERGUY]

Definately clean the optics... Thats always a good thing

That first pic shows a stray beam sneaking up from the galvo's...
Again... could be catching the edge of the galvo mirror.

One step at a time... house clean the unit.... then maybe tweak your alignment and make sure that green beam has a clear path to your screen

Laser Guy

[parodia-dn]

Ok guys, you help me a lot.
i`ll do all the stuff you saying, i hope i can fix my laser and post the pictures of it working well in a near future...

meanwhile i just want to thank you for all this information and ask for apologise for my poor english.

btw i`m not the guy in the picture without a shirt, but he works with me, all my crew laughs a lot because the Laserman532 joke....

[LaserLover]

^Well to be fair we did say it MIGHT be mode-hopping, which is a perfectly valid possibility.. The only way to know for sure is to check the beam profile before the beam reaches the optics path inside the scanner, or to work out the possibility through trial and error.

I agree that mode hopping is a possibility, specially If the DPSS laser temperature is not properly controlled or over-driven but the problem is likely misaligned optics.

If you have a Pangolin controller then you can lower the laser power output to test my theory on mode hopping and over driven lasers. if the problem goes away when you drop the brightness to say half power then it's possibly a thermal problem. if the problem remains then you have an alignment problem.

Good luck