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Thread: Too much of a good thing?

  1. #1
    Join Date
    May 2013

    Default Too much of a good thing?

    I thought I would throw this out for debate:

    Back in 1992/1993, I was lucky enough to get to run the planetarium projector for laser light shows (I think I was a sophomore in high school then so it was a pretty sweet gig for my age.)

    Anyway, at the time the planetarium was using an American mix gas laser, but the tube eventually went bad and it was quite a struggle to get any red or yellow out of it, so the American was replaced with a Coherent Purelight mixed gas running at 5 watts.

    Though my responsibility was for the planetarium projector and sound, not the lasers, I always felt the shows were more magical on the older laser running at lower powers (I don't recall the exact power of the American head but it was aging so I am sure it wasn't up to spec anyway.)

    Why you might ask?

    Well, in this planetarium, 5 watts just seemed to be overkill. The laser was so bright it turned the theater to near daylight and you could easily see people all the way across the room.

    On the old system, the laser did not light up the room, and the stars added a very cool dimension to the shows that was completely washed out by the 5 watt Purelight.

    I sometimes have similar feelings when I see modern videos of laser displays with numerous RGB projectors wildly sending beams all over the place. At some point it just seems to be too much as a good thing. I seem to enjoy a smaller production with just a handful of projectors well orchestrated to the music than a dozen projectors going berserk all at once.

    Anyway agree? Disagree?

    Incidentally, anyone know of some good star projectors a hobbyist might employee for small shows ("small" meaning maybe 1/2 the size of a school gymnasium just to define what I consider small.). They don't have to be perfect accurate, but I'm not looking for a night light either. On the same token, I want to invest money in my laser, not a Goto Mars planetarium projector!

  2. #2
    Join Date
    May 2007
    1 hr from everything in SoCal


    I would definitely agree with you. This is one of the reason why my latest projectors are using the lower power, single-mode diodes. I stepped it back from 1w to about .28w. I know that beam quality doesn't apply to ions like it does with diodes since ions are perfect but, making a long story short, the power loss wasn't a big deal for me. I found that 1w of RGB in my living room had to be attenuated because it was too bright.

    I am with you all the way. Bright is really only punchy for beams IMHO.
    Those who fail to grasp art are the ones who criticize it.

  3. #3
    Join Date
    Jan 2007


    Yeah I agree, I'm not particularly fond of the multi-spazz wild light going everywhere shows. Maybe it's just 'cause I'm getting old, but a nice slow moving liquid sky effect is much more pleasing to me than a bunch of stobing beams that I cant watch because they're moving around so fast.
    Oh, and welcome to PL MountainGoat! Looks like you've had some years of good experiences with some fun coherent photonic equipment

  4. #4
    Join Date
    Apr 2007
    Costa Rica


    That's exactly right. Too much laser power ruins the contrast ratio of the imagery to the background. The higher the contrast ratio - the more the laser vector graphics look 3D, like they're floating in midair. My motto is usually "Too much is better than not enough". But, more is not always better in a planetarium. Too much power lights up the room from the scatter. Smoke can cause the same problem. We built some special order SP164 kryptons for Laser Images when I worked at Spectra Physics in the seventies. Besides wanting the beam coming out the back end of the laser and a 165 rear mirror tuning plate on the 164 aluminum extrusion resonator, they specified 1W of red (with red-only optics). These lasers produced about 1W total of RYGB with white light optics. One watt spread over 4 main wavelengths / 4 XY scanners plus lumia and diffraction gratings produced great results even in the larger planetariums. You can't just turn the current down on a 5W white light ion without changing the color balance.

  5. #5
    Join Date
    Nov 2007
    SoCal / San Salvador / NY

    Thumbs up

    Hey MG -

    Quote Originally Posted by MountainGoat View Post
    ...Anyway agree? ..
    ..Between the '7140 for Dummies' thread and this gem of a post, I can see we're gonna get along real, real well... I could not agree more, about the 'craftsmanship' of a show.. subtleties, nuances.. and 'The Power of Black'™

    ..A well-proven 'other approach' for taming a 5W WL in a Pla, tho, is One-of the ways Laserium-pj's did it.. 50/50 the incoming, and then 50/50 that 1/2 of the Main beam, between 2x RGB channels (which 'eat' a good amount of light thru each of the 2x PCAOMs..) then, use the 'waste' beam for lumia / fiber-fx / raster-scan / special-fx thruputs, and with the 'other 50%', split that between 'Rail fx' (more lumia / scan / diffractive-fx..) and an entire 'Layered Lumia' / sfx section, that worked wonders, for the variety needed in a 'Cosmic Laser Concert'.. Like the 'philharmonic orchestra', you've got a bit of everything, not just MOAR of everything, all at once..

    ..'bout the worst thing I'd ever heard of was a well-known 'power-lusting' Sho Co out there, trying to 'resolve' a Pla-install they had's complaints about 'too bright'..... By offering 4 more *10W* RGB boxes! Talk about 'missing the point'! Needless to say, they don't have that Pla anymore (..and, worse, don't seem to care.. ) but.. those are the 'wham-bam-thankyou-ma'am' Co's for ya.. Send art and craftmanship to the gallows, and only lust after 'moar moneh', and that's - in the end - all you'll have... Which is all going to go to pure sh* sooner or later, anyway...

    ..Gold and Lasers.. the Best Investment for 2015 and beyond..

    ....and armed only with his trusty 21 Zorgawatt KTiOPO4...

  6. #6
    Join Date
    Feb 2011
    New Hampshire


    In general, I would agree with the consensus here, but...

    There is an important role for power. Jon's "the power of black" lies in the contrast or the counterpoint to the bright beams. The punch of a 40W beam is impressive as well and further extends the range of a show. No matter how good the beams and the scanner, a 1W RGB will seem limited when compared to a show with four, 1W RGBs and even more so when compared to a show where a 10W green is also used (hopefully, very sparingly).

  7. #7
    Bradfo69's Avatar
    Bradfo69 is offline Pending BST Forum Purchases: $47,127,283.53
    Join Date
    Jul 2010
    Wilmington, DE


    For graphics and lumia I somewhat agree. Not necessarily lumia but definitely graphics in a planetarium. There are times too when, at least in my venue, the termination of beam shows against the walls make it too bright in the room. I was messing with about 3 watts of RGB lumia tonight and there are plusses and minuses. What was on the wall looked great being nice and bright but, since the rig is not enclosed yet, the reflections and scatter from the wheel and even off the dichros bouncing around the rest of the room were annoying.

  8. #8
    Join Date
    Jan 2014
    Los Angeles, California


    Quote Originally Posted by dsli_jon View Post
    'The Power of Black'™
    YES! Sometimes the most powerful thing you can do with lasers is to turn them off
    Freelance Laser Operator in L.A.

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