Blue beam quality

[Zoof]

Yeah your right, it is two beams. The weak one is only a few mW. I've been experimenting with ways to block the weak side with a small metal plate. Results aren't bad at all. When placing the "filter" 50 cm away from the head I can get a clean oval beam with an aspect ratio of ~5:6 at full power (65mW) maybe even better if I get a concave beam block. Moving the filter closer to the head makes it harder to place the edge of the plate right inbetween the beams and results in scattering. I would like to move it in a little closer so it fits nice within my setup.
How clean the beam is really depends on the quality of the edge of the "filter". I figured using metal would give the best results, preferably factory cut edges. I haven't tried a knife edge yet but something like that might give best results.


Allthat: the pics at the top of this thread were taken at ~15 ft. Divergence seems to be OK.

[allthatwhichis]

You sure you don't have a optic in the wrong place? Maybe tilted?

That seems like a lot of work to get a good beam. Might I ask where you got it from? I've mentioned this forum to two of the last places I got a laser from and it seemed to quicken them to assist me. Not sure why... I still ended up with a green laser with no IR filter, but I got a nice blue. My red came from a fellow member so you know it's the shit.

[Zoof]

Got my red and blue from Nicolai Pusch on ebay. I got the impression that he sell good lasers, green and blue are CNI's red are manufactured by themselves. I'm pretty impressed by the red, which is a peltier cooled 100mW red at 650 nm. OK, he sold it as an 645nm but using a difraction grating I established that it is closer to 650 than 645. OK that 5nm really makes a difference when looking at the human-eye respose in that region but still it should be a lot brighter than 660nm. It is actually a convergent beam that starts at 5mm but gives a very tight spot on the wall and circular (for a change). I'll post a review of it in a while.

The blue, I'm not sure about. The seller, Pusch, has answered only once to my various emails about this laser. Offering that if I'm not happy I should return it and get refunded. So that clears him from all blame of being a 'scamming' seller. Though I should get more support to solve the problem. The only real problem with this laser is the discussed beam issue.
I've been debating with myself if I should return it or not. If I do I'll need to find a new blue dpss, maybe a Lasever but I'm now a little sceptic and afraid I'll run into other issues like bad blanking. Directly ordering from CNI is another option but I haven't seen them on this forum and their shipping prices are out of proportion - at least in the quote I got from them a while back.
Oh, and I got this blue on ebay for less than CNI sells them so I can imagine that the seller is not eager to send me his best unit, but that just sucks. I've given him a week so now I'll start calling him on the phone....

any words of advise?

[allthatwhichis]

Hey, I won my blue in an auction on eBay. I ended up with a 75mW for less than $600 shipped. eBay "can" be a good place to get an inexspensive laser, but you can also get a cheap POS laser there also. It's the eBay Factor... The allways varying chance you'll get a good deal. I was going to say call the seller of the laser I got, but they are one of the few sellers in the states that I know of, and you're not in the states...

Have you checked the optics yet?

[Zoof]

Opening the laser will void warranty and spoil my option for a refund. I tried to discuss this with the seller - but no replies form him. If he gave me a proper discount on the unit I could agree to have null warranty and then I would be free to open it up. My guess is a thermally disadjusted optic, probably the cavity alignment with the pump beam. When the unit is cold (10deg C) it has a three-lobe beam but as it warms up that transitions into almost circular and then settles into the two-lobe beam with a weak side.

[Zoof]

Are there any pictures around of the CNI blue's internals?

[allthatwhichis]

Yea... I'm kinda anal and that'd drive me insane. I can't really make any suggestions then. If he has not answered emails a refund may be a pain in the ass. Is your warrenty with CNI? May want to look at that route.

[Zoof]

Yeah it can drive a man insane. I've previously onwned two green dpss's and neither of them had a real TEM00 beam. The first, a 50mW Lasever (2004) was definitely the best: a circular spot but with an uneven power distribution. I sold it to get more power. The second was a 140mW LambdaPro which resembed a green search light. Tremendous mode hopping, and blurry spot on the wall plus a lot of scatter. That one I opened up (voiding warrenty) to see what I could correct but the wire connections inside were such a mess that it didn't take long before one of the diode wires was stressed too much and broke of at a solder connection where a cap was put across two wires (real messy). I ended up replacing the diode, rebuilding the inside and realigning the cavity with the diode. Pics. After a few restless nights (talking about anal) I got a TEM00 beam over the whole power range. So it can be done. However the driver and rest of laser was still crap: the warped base plate really prevented any proper alignment. Ended fidling with it every night instead of building a projector so I sold it off to a student who wanted to do just that. (for a minute there I thought I could shake the laser bug ... silly me ) A year later, now, I find myself again with a messed up beam on a dpss.
Really don't want to go through all that again...

[allthatwhichis]

Damn, that sucks, sounds like you're already halfway there. I wouldn't take it apart, but most here would, that's why I suggested it. I'd send it back and try to get him to cross ship me a replacement. I'd also flame him here and send him links until he replied, especially for a blue.

[Zoof]

well I've done it once, very educational when I still had the time and lack of commitments. Things change, less time a little more $$ so I figure I should buy good components for the project.
Anyway the story continues on this laser - another defect is revealed: noisy beam - when scanning larger scan angles the lines are specled randomly over time. This really shows when the scanangle increases 20 degrees and above. The problem could have originated in a number of components (e.g. DAC, P/S) but it is the blue again. After connecting the modulation input to a 4.5V battery the specles were still there. At times they dissappear and the scanned lines are smooth but the specles return. Well.. the battery does not have noise so the modulation circuit must have it. Again, I don't have any reference what to expect from a blue dpss but this one isn't making me happy.

BTW, this one cost me $613 shipped: 65mW analog. Too bad it doesn't work properly.