I just can't get anythng better than 2.2mrad

[Bionic-Badger]

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

No, there's a balance between the two, as divergence is inversely proportional to the minimum beam diameter. Beam minimizers will produce a beam that is smaller, but it will have larger divergence.

So you really can't have your cake and eat it too.

 

[Uranium]

I just wonder why this beam is being so stubborn.

 

[Trevor]

I just wonder why this beam is being so stubborn.

A higher order mode beam usually has worse divergence. Not all that much you can do about it.

Maybe take the module apart for the crystals for a later project, replace the laser, and invest in a wrist strap.

Even the best zombies have a point where they can no longer rise again... :yabbem:

-Trevor

 

[Uranium]

A higher order mode beam usually has worse divergence. Not all that much you can do about it.

Maybe take the module apart for the crystals for a later project, replace the laser, and invest in a wrist strap.

Even the best zombies have a point where they can no longer rise again... :yabbem:

-Trevor

No way, it's still a great laser. However i've always wondered if a more powerful diode could be attached to the crystal assy. I doubt the company that makes these use different crystals for the other powers. This isn't some cheap 5mw laser. It's a "real" one with quality crystals, so it should be able to take more pump power. I'm not willing to take it apart yet though, as it is my most powerful green laser. I don't want to break it.

 

[goninanbl00d]

Have you got a picture of the beam after it has been through a magnifying glass to expand it?

Or in which case, if it does have a 'broken' transverse mode, you could consider replacing the actual module with one of similar power:

http://www.o-like.com/index.php?main_page=product_info&cPath=2&products_id=45

I'd still try playing with optics first.

If you want, you could try realigning the actual crystals themselves to improve the beam quality.

 

[Uranium]

I can't get a decent pic. The camera blooms too much. However the beam's a perfect square. It mode hops as it warms up over 3 minutes. However the mode's aren't the usual TEM modes. They look much more like (exactly the same as) the modes in this video. It's the oddest thing.

YouTube - Cymatic experiment

 

[goninanbl00d]

Try getting a picture through your goggles.

I'm assuming this is the Rayfoss RF532-250-02 unit, rated for 250mW?

Does the dot look like this after it's warmed up?

If so, you have mode-hopping problems. The picture's from somebody else's review of this unit.

It's a dirty beam profile. They're very hard to work with even with good optics, and as someone else said, the higher you get with transverse modes, the higher the divergence.

 

[Uranium]

Yes, that's what the beam looks like. Not much i can do with it i suppose then.

 

[goninanbl00d]

You could try correctional optics, but they'd only be able to do so much.

It sounds like you just have an unstable module, so there wouldn't be much point trying to re-align.

Your only other option is to replace the module completely (driver, diode, crystals).

 

[Uranium]

Well, it does put out a lot of power still. I suppose i'll just have to live with it. Maybe when i get some extra cash i'll put in a stronger diode for fun. However what could cause it to be unstable like that? Maybe it is fixable somehow.

 

[goninanbl00d]

I'm no expert on DPSS, but it could do with misaligned or damaged crystals, a damaged/misaligned pump diode or damaged optical coupler.

 

[Uranium]

If the crystals were damaged it wouldn't lase at all, let alone at a few hundred mW. The OC seems fine, it may be the diode. Well, when i get some extra cash, i'll put in a new diode. That still wouldn't explain the mode hopping though...

What power diode and what form factor does rayfoss use in the 600mw lasers? I don't want to take apart mine to check, because it still works. I'll still have to build a new driver, unless there is a pot in the one in there now (still don't want to check).

If anyone knows more about these lasers, please tell me the knowledge you're neurons have in store.

 

[goninanbl00d]

You should be able to unscrew the head to see the module. It will be easier to replace the whole module (drivers/crystals/pump)

Misaligned and slightly damaged crystals may still lase, but they will be extremely unstable and prone to mode-shifting. That's probably what's happened with your laser.

 

[Uranium]

I've seen the module, and unscrewed the oc. There's not much to see. I just can't imagine the crystals lasing at full power if they were misaligned and/or damaged though.

Does anyone have pics of a completely disassembled laser?

 

[goninanbl00d]

Do you have a picture of the module without the head on?

Also- the output lens may not be the OC- the OC is usually directly in front of, if not on, the KTP.

EDIT: An unstable power supply may also cause mode-hopping. My 50mW green module would mode-hop but still lase at close to full power if the connection between it and the battery came loose.

 

[Uranium]

Well, i mailed LPP about the problem, and here's the response i got. Is there anything i could do to fix it? Re-align the crystals maybe? I wonder what is causing the hopping. Even unstable though, i still value it enough to not destroy it. I suppose this is my chance to put a stronger diode in too.

I bought a 250mw Toplaser II in august 2009, and it has always mode hopped. It was supposed to be a TEM00 beam, but it mode hops between TEM22 and TEM33. I have tried to collimate it with all kinds of lenses and have gotten nothing better than 2.2milliradians. I only found out now that the high TEM mode was the problem. Since my laser is still under warranty, I would either like the problem fixed or the laser replaced. However, since shipping to china is not an option for me, (it would cost $120), could you just send a new diode/dpss module? I know how to replace it.

Dear XXXX,
Hi, this is Wong, and hope you're doing well.
I got your point and we're afraid we might fail you at this, and this company went through a lot of corporate restructuring eariler this year and LaserPointerPen.Net was finally bought by the current manager now, the boss of a HongKong company. The personnel also changed a lot and I'm just one of the new employees who came to work here at this March, 2010.

And you may see we no longer resell the named Toplaser laser products now, probably coz they're not top quality ones, while we mainly sell some cni lasers and jetlasers laser products now, two top notch manufacturers in China, and we believe you may order the Toplasers last year and we also don't know if it expires the warranty or not, we're really sorry that there might be little we could do about it.

BTW, the laser diodes the lasers here are made of are the nLight ones and the Axcel diodes(index ), and if you're in US now, you may be able to get one or two diode samples from them at a much better pricing than from local China. Hope it helps.

We deeply apologize for the inconvenience caused by the company adjustment here and talk to you later.

Best regards,
Wong