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FrozenGate by Avery

I just can't get anythng better than 2.2mrad






The module looks to be a self-contained unit. There appears to be an optic or crystal visible in the second crystal.

The bad news is most times DIY DPSS repairs don't end very well. If you wanted to take the risk you could try breaking the glue and moving the internal components around slightly to see if you can get a better beam profile.

On the upside, however, there's near-identical replacement modules available at O-Like.

High power 300mW green laser module/IR filtered [OLHGLM250] - $225.00 : Welcome to O-Like.com, Your source for laser products

So, if you're willing to take the risk (it may pay off, but consider it carefully if it's your only high-powered laser), then you could attempt to re-align the crystals.

Generally, TEM22 and 33 usually indicate crystal problems (as opposed to 01 and 10 which indicate power source or temperature instability.)

In the end, it's up to you.

P.S. I'd also suggest getting the thing refinished, sealed and polished at the local machine shop. It'll look like an RPL afterwards :D
 
Uranium said:
Yes, that's what the beam looks like. Not much i can do with it i suppose then.
Click to expand...

In reality, given the organized structure of that pattern, you probably have a multimode green laser. Very often I've found that with higher-powered cheap greens the beam is actually multimode, and would seem to have been intended that way to get more output from smaller crystals. The printed specs for Chinese lasers are not always accurate.
 
I've decided not to screw with it. It's the most robust laser i've ever had and i intend to keep it that way. BTW, the KTP seems to be the standard 2x2x3. I can't see the vandate w/o taking it apart.
 
I fixed it! 1.8mRad now. How? A hammer and a little anger.

I still have about 7% scatter from the uncoated lens, but IDK good enough. Beam seems to be stuck on tem 01 now, no fast axis.
 
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Uranium said:
I fixed it! 1.8mRad now. How? A hammer and a little anger.

I still have about 7% scatter from the uncoated lens, but IDK good enough. Beam seems to be stuck on tem 01 now, no fast axis.
Click to expand...

Ha, umm. Glad you got it at least partially fixed.

I'm amused that you wouldn't take it apart for fear of breaking it, but you ultimately took a hammer to it. :p

-Trevor
 
TEM01 isn't any better than TEM22.

Better have a geometrically-perfect and neat square beam than a two side-by-side ovals.
 
Uranium said:
Nope, this. I'm stumped. (no it's not a failure mode, because it hops to this after a 5 second warm up of random mode changes.)
Click to expand...

Uhh. You've seriously screwed up that laser. Yet it's somehow really fascinating. :p

-Trevor
 
I'm not doing any holography or interferometry with it --just burning and pointing, so it's all good.
 
Spoke too soon. Apparently i miscalculated. Still 2.2, oh well, i've given up.

You say that higher TEM modes are harder to focus, however during it's warm up it jumps to really high modes TEM44 and above, yet the divergence doesn't change. So i'm not so inclined to believe that...
 
What causes the beam's divergence to be crappy? The beam has no fast axis, (perfect square).

Oh yeah, bump.

Also, if anyone wants me to list (in pictures) the wacky modes this laser has given me, just say so.
 
steve001 said:
So tell me what is it you want. 1. lower divergence ? or 2. A beam of less than 3.5 mm dia. ?
When I buy a lens I use Optics, Imaging, and Photonics Technology - Edmund Optics. They have a very wide selection of lenses [ singlets ] that are AR coated or uncoated.

One thing clean off the glue from that lens and try this glue instead Bond 527 or Beacon 527 for your next lens. It's easily peeled from the lens yet will hold the lens firmly in place without damaging the AR coating. Only glue at the circumference of the lens to the host. I use a tooth pick to apply this glue.
Click to expand...

Lower divergence and smaller beam diameter are essentially the same goals, since they can be interchanged with beam expanders or contractors.

I suppose the first thing to do here is to assert that your dpss unit is functioning properly - run them beam through a lens and make sure that what comes out is a single spot, not some odd multimode pattern.

At 3.5 mm diameter, you should be aiming for a divergence in the order of 1 mrad or so, perhaps a littlle bit more. If that cannot be achieved using any optics, i'd suspect the laser to be faulty.
 
I've fixed this problem (1.9mrad). Problem is the lens I used is uncoated.
 
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