Dillemma

[yaddatrance]

You're running into a classic laserist's dilemma... You have a budget but you
need power... First off, forget outdoor beam shows until you have the cash
for offboard equipment... Unless atmospheric conditions are just right,
you'll need about $2000 worth of foggers (even using 40W YAGs )... I also
recommend running the heck away from mid-frame (6W Argon or Krypton
class) lasers... The problem isn't the tube and it isn't the 3-phase... it's the
lack of reliable power supplies, or more specifically, power supply designs.

You have realistically two options in your stated price range...

1) The easy way out: If you have $500, I'd thow that into the brightest green
you can get your hands on... You can't beat the price performance of
532nm DPSS. And for $500, I'd be dissappointed if the green didn't have
decent onboard modulation... Since modulation circuits usually add $50-100
to the cost of the unit, if you insist on using the AOM (and the source laser
is sufficiently polarized) you may gain a few mW at the same cost by opting
for a non-modulatable power supply. $500 should get you >150mW of
reliable 532nm green...

2) Blood-sweat-tears route... The alternative is to go for a Medical argon such
as the HGM5... This is where the AOM will come very handly... It's not
uncommon to find used medical argons in that price range... Out of the
box, these units are not "entertainment-ready" and will need to be tweaked
and recased to be useful. Make sure the unit supports CW output. You
can expect to see >350mW of argon with this route, however most gas
lasers which truly output >300mW of power (i.e. not an ALC60) will require
240VAC (single-phase)... The only exception is the LaserPhysics (now
deceased) Reliant 250D and the OEM dental version of the same...

Reality checks:

One thing that you may not be counting on is that you'll see a lot of
power loss through an AOM than compared to say diode modulation or
scanner blanking... A big pain about most surplus AOMs is that the
crystal size is tiny so alignment can be annoying... I avoid AOMs as much as
possible, after all, aligning a PCAOM is at the same level of difficulty.

In terms of "why a more expensive laser at the same power level"...
Entertainment lasers are a very low margin field so the cheap lasers
got there by taking a lot shortcuts... This will exhibit itself as lasers that
die prematurely and catastrophically, when doing graphics, the specification
that lists "power stability" is dramatically visible as hot and dark spots...
The second problem is that many people use IR in their power specifications.
Your 100mW green laser may only be outputing 40mW 532nm of green with
the remaining 60mW leaking out as 808/1064nm IR...

It's all just a case of caveat emptor.

In my personal case, the difference of a few hundred bucks is not worth worrying about all the cruft in the the industry... especially compared to the
investment I've already made in everything else... so I just stick to reputable
vendors and avoid all those messy problems entirely...

Unless you're dead-set on going argon, I'd sell the AOMs and get a diode by a
reputable vendor... In terms of your "laser doesn't come back to 100%"
problem... That is strictly a diode driver issue... There are of course limitations
to BIG solid-state lasers due to population inversion, but in the scale we're
talking about here, you only need >30kHz modulation to be FASTER than the
scanheads themselves! Suffice to say I have no problems with fast diode
modulation... An example in point is that at my place of occupation, we
routinely run laser diodes past 50Ghz modulation. There are no problems with
slew rate at those speeds...

[QUAZAR]

As far as outdoors go: 40W. Minimum. There really is no way to make outdoor beam shows with only trace amounts of dust in the air. Some even say that 40W looks cheesy. If i was going outdoors with anything id want a couple copper vapor lasers. Wonderfully bright gold/green lines are produced by those things.

This picture was taken at an outdoor show I did a few years ago. We used a S.P.2011 @ 6 watts. There were about 1500 people present.

[buffo]

Did you have a fogger or hazer operating? It looks like it from the picture... (And if so, where did you find a fogger large enough to do an outdoor show for 1500 people.?!)

Also, you are lucky to be in the UK where you can bring those beams right down to head level with the audience. If the eye is only a few degrees away from the beam, even a low power beam looks good. But here in the US those beams would need to be a minimum of 10 feet off the floor, which means they'll be less visible without some fog in the air. (Or a lot of power.)

I can't be sure, but from the picture it looks like some of the folks on the left are right in the beam path. Is that just an illusion, or were the beams really that low? Either way, it looks like it was quite the show.

What is the plume of smoke seen on the right of the picture from?

Adam

[QUAZAR]

We has a Jen ZR20 smoker on the stage, not really designed for outdoor use, but as the field had tall trees around surrounding it, there wasnt too much of a problem with wind dispersing the smoke.

No crowd scanning at this gig, the local EHO was present all night. At one point (about 3AM) , he was on the stage with a beer telling us this was the best party he had been to in several years.