How much DPSS power from <1mm at aperture?

[The_Doctor]

It's been a while since I checked, but 3mm wide beams seem to be what to expect from a 1W+ DPSS green. Did anyone manage to get that down to 0.8mm, with divergence of about 0.5mr? That spec used to be available up to about 200mW I think, but I imagine more might now be had. How much more, and who makes it? Likewise, what can be had with similar specs in 473nm?

As a slightly off-topic question, having seen what looked like a page advertising a 660nm DPSS, can anyone tell me more about those? I know that such wavelengths usually mean diodes sold by keyword spammers jumping on the 'DPSS' bandwagon, but the specs given were very DPSS-like, and very un-diode-like. (Specifically, crystal related to KTP mentioned, and immunity to optical feedback) Here: http://www.cobolt.se/coboltflamenco660nmlaser.html ... but are they alone in this, or are other people making them? And is their cost as horrifying as I think it might be? Quantify that in SI units if you dare...

[absolom7691]

I don't know about 660nm but I believe Kvant has DPSS reds at 639nm. http://www.synchrovision.co.uk/produ...r-module-kvant

To my knowledge, they are 445nm pumped. Given how unstable DPSS is with modulation and how red diodes are coming along, I am not sure how much future this has. I could be wrong though. Still, DPSS have a hell of a lot better beam specs so.....

[andythemechanic]

Given how unstable DPSS is with modulation and how red diodes are coming along, I am not sure how much future this has. I could be wrong though.

The unstability in the green or blue DPSS comes mainly from frequency doubling. These new red and orange lasers from Kvant don't involve any doubling so I would assume they are much more stable under modulation.

[absolom7691]

The unstability in the green or blue DPSS comes mainly from frequency doubling. These new red and orange lasers from Kvant don't involve any doubling so I would assume they are much more stable under modulation.

Thanks for that info. I know very little about these new lasers. I wasn't aware that there was no SHG in these. Sounds interesting, for sure. 2.5mm beam at aperture and 0.3 mrad.... hard to match that!

[The_Doctor]

Thanks for that info. I know very little about these new lasers. I wasn't aware that there was no SHG in these. Sounds interesting, for sure. 2.5mm beam at aperture and 0.3 mrad.... hard to match that!

With or without frequency doubling, what I'm trying to find out is how much power can be got from 0.8mm or less at divergence around 0.5mr, not more than 1mr. The specs you mention are good, but I'm not sure if those are native best, or an attempt to match best direct diode specs. (A pair of lenses will likely turn 0.8mm/0.8mr into 2.5mm/0.3mr without much difficulty).

My point is that if new crystals are emerging to produce visible wavelengths, why are people on PL messing with anamorphic prisms to clean up beams, etc? If instead all these new strong multimode diodes can pump new crystals to get clean stable TEM00 beams less than 1mm wide, diverging less than 1mr, with fast stable linear modulation, AND total immunity from retroreflection death, isn't that an embarrassment of riches beyond compare? It seems to me that this approach will make almost all others redundant. If I can get three decent colours for RGB this way (without the SHG), that's what I want to do.

So given that we might be back to looking at VERY THIN beams as a standard, I ask again, what's the best known power output for various visible wavelengths in beams around 0.8mm and <1mr? (I'll include SHG in that question for now, as I doubt that all colours for RGB can be got without it in thin beams yet, or at least not cheaply enough to convince people to use them in shows.)

[andythemechanic]

Voila: http://www.ipgphotonics.com/Green_CW_Laser.htm

>100W in single transverse mode.

[The_Doctor]

That is so cool! A wee tad bit beyond my budget, no doubt.

[danielbriggs]

You could get 1.1mm @1mRad @532nm, (or it's native 2.25mm @ 0.5mRad) quite easily at 20W; linearly polarised, so 40W is trivial.

[absolom7691]

My point is that if new crystals are emerging to produce visible wavelengths, why are people on PL messing with anamorphic prisms to clean up beams, etc? If instead all these new strong multimode diodes can pump new crystals to get clean stable TEM00 beams less than 1mm wide, diverging less than 1mr, with fast stable linear modulation, AND total immunity from retroreflection death, isn't that an embarrassment of riches beyond compare? It seems to me that this approach will make almost all others redundant. If I can get three decent colours for RGB this way (without the SHG), that's what I want to do.

I think it largely depends on cost. I have not priced these yet but I would wager that the cost is of DPSS red to red diode is 5:1 at best as far as $/mW. Sure, diodes do not have the beam specs of DPSS and probably never will but for most of us, I think they are passable until something economically powerful and clean comes along. I understand that this is probably expensive because it is new tech and the crystals for these are probably not being produced on a mass scale yet. Hopefully they will come down in price and give the laser community a nice assortment of lasers and wavelengths to choose from.

[The_Doctor]

You could get 1.1mm @1mRad @532nm, (or it's native 2.25mm @ 0.5mRad) quite easily at 20W; linearly polarised, so 40W is trivial.

My question begins to look foolish. I'd forgotten Verdi and other ring lasers... Ok, to redo the question: What is possible given the kinds of lasers from Lambdapro, Lasever, CNI, Laserwave, etc? The kinds people usually buy fairly cheaply for projector use.. Of those, I saw 0.8mm beams with less than 1.2mr divergence, till about 200mW or so, then suddenly the Lamdapro lasers got big, beam specs went all to hell, and I stopped wanting to risk going for higher power that way. I'm thinking that things may be better now, but also that it might be hard to tell, given that demand has made the makers aim for wider beams to match direct diode output for other colours, especially red. To put a different question aimed at getting an alternative view of the same situation: What is the cheapest 1W green DPSS with a very fine narrow low divergence beam with good lifetime and TEM00 stable output and good analog modulation? I looked at a few maker's sites last night, and it's getting confusing, lots of offerings, and all apparently with fat beams!

EDIT:
If I want larger beams and less divergence, I'd rather add that myself than have to void a guarantee by removing lenses put there by the maker when I want a very thin beam at aperture.