5W RGB Projector using 3 diodes

[steve-o]

Hi All,
I have a proposal for discussion. Can a 5 Watt RGB projector be built using only 3 laser diodes (except dpss for 532) for ease of alignment and simplicity. For the 1:1:1 ratio, each diode / dpss needs to produce 1.667W of output power. I believe I have read that the new 9mm 445 LDs can produce this all day long with no probs given adequate heatsinking/cooling, and are fairly easy to tame. A green DPSS with this power can be purchased also w/ no problems either (just fairly expensive, but not too extreme.) That leaves the red. Choices? 638-642nm? 650? Matching beam profile for the other 2? I have a P73 Mitsu LD that I push at over 800ma giving around 600mw if I recall correctly. Has anyone driven them harder? Any other diodes discovered out there? A single red diode pushed past the limit would have to be replaced fairly often (just like high power tungsten or xenon lighting) so a quick-change drop-in pre-aligned mounted-diode module would be cool. Also, it would be nice (imho) if the 1.67W 532 green was a "pointer-core" type if any are available at this power. Ideas? Disapprovals? Laughter? :]

[kecked]

use three opsl lasers and your done. You didn't say anything about a budget.

[steve-o]

^^ LOL luv it.

[steve-o]

Ok, 90 bucks for the blue diode, 100 for the red, ~500 for the 1.6W green core, and 400 for all coll/corr/misc optics/mounts and holders. Oh yeh.. and a TEC for the green. No enclosure yet. There's your budget

[Solarfire]

If you get that 1.6W green core for 500 let me know I could use a couple of these...

[matratzki]

For such a budget, you are not even allowed to watch a opsl taipan ^^

[kecked]

Here is a real answer.

The best you can do with any quality in the beam and without going to large efforts is to use a 500mw DHOM green laser, 1 9mm 445nm blue doing around 800mw , and 4 170mw 638nm reds in a combiner (two knife edged with a pbs cube). Add to this a DZ/Stanwax color correction board or an eyemagic iris and a set of cambridge 60kps scanners. You should be able to do it all for about 3500-4500 usd. This gives about 1.5 Watts of balanced white light with a good beam profile. I did not mention the drivers or correction optics for the blue. This is pretty much what I have and it works well. I got it all in a box that is 18"x12" with a 6" high top and 6" high bottom for the electronics. The base plate is the heat sink for the whole thing. I used an optical rail (not my idea. I lifted that one from Raven Systems) to hold all the dichros so it took a degree of freedom out of the alignment equation. dichro stock came from Fred at OneStopLaserShop. The limit on my projector is clearly the red source. IF I could get a better red source I could easily up this projector to higher power which is why I mention it. I think you could easily double it with a better red system to 1W Green, 2W Blue, 2W Red for that 5 watts you want.

I have to ask. Have you ever actuall seen a 1W of whitelight? It is painful as hell in my living room. I have to dial it back a lot. Plus it lights the whole room up detracting from the contrast ratio which is the point of using lasers. I actually tried using a black cloth to drop reflections. It looked as brights as my old hene argon pair on the wall but the contrast is much better.

One last point. DPSS really sucks for modulation unless you stay below the knee of the laser so if you want 1W of green you need a 2W or better laser. This is why I'm going the other way to single mode all diode lasers. It might only be 200mw when I.'m done but it will be 200mw of perfect light.

As for beams.....not my thing.

[steve-o]

Thanks for the real input Kecked. I do outdoor beamshows. No indoor stuff at all. That's why 5W. Yes I've seen whitelight gas ions pushing many watts in concert halls and coliseums. My favorite was a ZZTop concert in Memphis back in the 70's. Everybody was smoking (everything lol) so the air was pretty fogged. They bounced that monster WL off a huge mirrorball (that thing had to be 10 feet in diameter) with a modulated beam and it was absolutely spectacular. I think there was probably over 1 watt of white at Selem 1 too (the only selem I've ever been to.) Anyway, back to topic, I like your ideas, I didn't mention correction boards and scanners etc because I don't want to dilute the topic too much. I know I said "projector" but it could be an alternative type. Mainly interested in the 3 laser-source. Modulation isn't my thing really, so not worried about the dpss green. I don't follow the crowd with super software and mega speed scanners. I do my own thing too. :] Congrats for going all diode including the green. Post some pics when u can!

[planters]

This sounds like fun. I have a much different approach. I agree on the DHOM green (I like these lasers by the way), but if you want to stay away from even a PBS and dual diode red and dual diode blue then yes, use the 9mm 445 and PUSH it. These are modulated and rarely going to see more than a few hours/week over the long haul and I'd say run this at 2.0 A and aprox 2.5W. For the red Use a P73 and chill it to -20-25C. Run it at 1.2A and 1.2W. The single (or dual) diode approach, besides its simplicity also allows the greatest amount of beam expansion for a given scanner mirror and therefore the best far field spot. This is key if your looking at ten's of meters.

If your running outside then you might want to go the dual route. As far a white, I disagree that all the lasers in a projector should have the same, balanced, linear maximum output. Any RGB projector can produce a white beam at some percentage of its maximum power level, but white is just one color. Granted that percentage will be almost completely limited by the lowest visibility color available( power x the eye's sensitivity). But, with the diodes becoming more powerful, red and blue are overtaking 532 Despite its previous visibility advantage it is becoming the bottleneck. Yet, so what? What would you rather have, a 500mw each of red, green and blue or 2.4W red, 500mw 532 and 4.8W 445? You could still produce the same colors with the more powerful, but you could also produce some spectacular magentas. Further, as the beams propagate thru mist/fog they change anyway. The blue will scatter more strongly and so a "balanced" beam will appear more blue along its path and then more red at the termination.

[steve-o]

Sounds good Mr P. Have you actually chilled a P73 and gotten 1.2W at 1.2A at -20-25C? That's cool !! (seems I remember a thread about this, but don't remember the details at the moment) ..