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Thread: Need some help! My first RGB projector project (expecting approx. 2W system)

  1. #11
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    Default Safety and Public Liability Insurance

    Quote Originally Posted by dave View Post
    If your intending on doing public shows, a saftey board is essential, as is public liability insurance.. Bad idea doing any public shows without either..
    Hi Dave,

    Yes, you are absolutely right. Both of these are vital.

    I have a safety board on order from Medialas as mentioned above.

    On the public liability insurance, do you have any guidance on suitable cover here in Australia? I may need to get my current policy modifed.

    Cheers,
    Tony

  2. #12
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    Default

    Quote Originally Posted by danielbriggs View Post
    I can't see this being a problem, but if you are really stuck and are loosing a serious amount through the galvo's. (I've not tried this BTW) but you could look at slightly focusing the 'white' beam, just before it hits the galvo's to a smaller spot size, then after the galvo's re-focus the beam with another lens placed after it's bounced off both mirrors. I don't know if this will work well in practise, just an idea off the top of my head.
    Interesting idea, would love some suggestions from the forum on the choices of lenses that might suit this. Also with safety in mind, would allowing the beams to diverge gently after the scanners, thus dissipating the energy, actually be ideal, rather than refocussing? In suggesting this, I am also mindful about the amount of divergence as you wouldn't want to lose the beams completely. I've read somewhere else here about a very large lens being attached to the front of the projector to achieve this energy dissipation.

    Quote Originally Posted by danielbriggs View Post
    P.S. What hardware+software are you going to use to drive it?
    At the moment, Mamba Black version 1 with USB DAC.

  3. #13
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    Default Another open query to add relating to ground isolation of components

    I just saw a post..

    http://www.pangolin.com/forums/showthread.php?p=1573#5

    William Benner suggests some isolation is required. Can anyone suggest a good set of rules on this for the typical components in an RGB system?

    I'm guessing that some grounding is preferable, as is some isolation as suggested by William.

    Cheers,
    Tony
    Last edited by taggalucci; 02-16-2010 at 00:40.

  4. #14
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    Default Some photos as promised...

    Here are some photos of where I'm currently at...








  5. #15
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    Default

    Laser from Laser century - opps
    KVANT Australian projector sales
    https://www.facebook.com/kvantaus/

    Lasershowparts- Laser Parts at great prices
    https://www.facebook.com/lasershowparts/

  6. #16
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    Default

    Quote Originally Posted by dave View Post
    Laser from Laser century - opps
    Are you referring to the larger laser on the right? The power measurement for that unit is 598mW and it has a nice clean beam.

    I take it Laser Century is not comparable with CNI, or am I onto something a little more special

    I bought this second hand and had been told it was from CNI (that's what it says on the invoice)! Got it for a great price IMHO.

    The Red and Green are definitely CNI though.

  7. #17
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    Default

    Quote Originally Posted by taggalucci View Post
    I take it Laser Century is not comparable with CNI
    Well, that's a polite way of putting it. (cough!) But you may get lucky. Just be sure that the 598 mw you're measuring is all blue, and not half IR leaking from the cavity... Also, it's possible that it will drift down in power with time.

    As for the schematic, yeah, I goofed on my last post. Sorry about that. Here's the link to the schematic I was talking about. (I also edited my original post to fix the link.) Just click on the image to get a larger version.

    As for your progress, you appear to have all of the major components already. Very good. I suggest that you draw a diagram of your proposed layout next, to be sure everything will fit, before you go any further. Draw it at 1:1 scale so you can see how things will fit together. Make sure you'll have room to get at the thumbscrews on the optical mounts to adjust your alignment. Also, look for ways to route the cables so they won't be in the way. And when you're happy with the layout, you'll be able to take measurements straight from your drawing to get the base plate cut to size.

    As for the grounding issue, there are two schools of thought. One is to connect all the DC grounds inside the projector to ILDA pin 25 (ilda ground), and then to also connect this to the A/C (mains) ground for the incoming power to the projector. Unfortunately, when you do this you create a ground loop between the projector and the host computer. Is this a problem? Usually not, but it *can* cause issues in certain circumstances. (Note: despite the fact that a ground loop exists, this is how I have my projector wired, and I believe most PL members also use this scenario.)

    The alternative is to break the loop someplace. And one easy way to do this is to lift the A/C ground on either the projector end or the computer end. Yes, this will break the ground loop, but it also introduces *serious* electrical safety hazards. Now, if you have a double-insulated projector housing (double-insulated on the A/C line, that is), then in theory you could operate without the A/C ground connected. This is not recommended, however, because of the obvious potential for electric shock (even with double insulation.) Likewise, you could lift the A/C ground on your host computer, assuming the CPU case was again double insulated, but this is also not recommended for the same reason.

    So that leaves you with the option of connecting all the DC grounds inside the projector together and tying them to ILDA ground through pin 25 on the ILDA connector while electrically isolating *all* components from the base plate and the projector enclosure. (Since the base plate and projector enclosure will be connected to the A/C ground.) So now you've eliminated the ground loop, but you've also grounded all the DC components through a single strand of #24 wire (in the ILDA cable). Still not an optimal solution, but it does eliminate the ground loop... Though electrically isolating a metal laser housing (which is usually at DC ground potential) from a metal base plate while still allowing adequate heat sinking isn't easy!

    This is why most people have everything connected to A/C ground and just live with the ground loop. And truthfully, I've never had any problems with this layout in my projector, though I have read about one or two rare incidents where it has caused a problem. (In those cases, the solution was to break the ground loop using one of the solutions above.)

    Re: insurance and scan-fail interlocks, I think you're better off listening to Dave, as he is quite familiar with the Australian law concerning laser shows.

    Adam

  8. #18
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    Default

    Hi Tony,

    Welcome to PL and the moneypit that is lasers....

    Looks like a lot of your questions have already been answered, but here is what I reckon on some of them

    Quote Originally Posted by taggalucci View Post

    Here are my current open queries:

    • I have access to 16mm aluminium for the base plate, is this overkill? I also have access to 12mm plate.
    I reckon you will have plenty with the 12mm, it would take a fair bit of heat to distort that... 8mm would probably suffice and drop the overall weight of the projector significantly, which is an important factor if you are going to be loading the projector on and off lighting trusses.

    Quote Originally Posted by taggalucci View Post

    • Does anyone have any experience with creating sealed optical areas? I would be interested to hear about the pros and cons and what materials would be recommended to provide the seal and what constructions process people may have used for this.
    I added a sealed optical area to my projector. Mine is all on one level, the optics on one baseplate sealed in an acrylic box with no fans, and the electronics on a second baseplate with fan cooling....

    Click image for larger version. 

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    If I were building this again, I would make two boxes, one fan cooled with my electronics and one sealed with my optics... A bit like this:

    Click image for larger version. 

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    Quote Originally Posted by taggalucci View Post


    • If a shutter was required for safety, as opposed to the alternative of killing power to the lasers, what sort of material should be considered a good beam block for 2W? What would be the most effective and inexpensive actuator for this shutter?
    Most important thing with a shutter is that it is spring loaded, so if you loose power to it, it will naturally close...

    Quote Originally Posted by taggalucci View Post

    • How would an interlock connect to the system?
    • How would a keyed switch on the unit connect to the system?
    • How would a remote emergency stop button be connected to the system?
    I think most of this is answered in Bills document that Adam sent you...

    With the 635nm and 640nm thing, you can get very high powered 640nm lasers from Dave in Australia or Martin (Pelosh) in UK made by Kvant. I believe Laserwave might do some as well, again Dave, Stanwax or Gottaluvlasers can help there.

    Here is a comparison.

    A white beam with 635nm red


    Click image for larger version. 

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    A white beam from a 640nm red.

    Click image for larger version. 

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    I use only 600mw of 640nm in my 2.3watt RGB and it makes a beautiful white..

    Hope that helps
    Mark

  9. #19
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    Default

    Hi Adam,

    Thanks for the schematic, the suggestion of the 1:1 mock up of the base plate and the very in-depth advice regarding grounding and isolation. I will give this all a good review to ensure I'm comfortably across it all.

    Quote Originally Posted by buffo View Post
    Just be sure that the 598 mw you're measuring is all blue, and not half IR leaking from the cavity...
    Apparently this laser is fitted with an IR filter. I also ordered the 532nm with an IR filter.

    Quote Originally Posted by buffo View Post
    Re: insurance and scan-fail interlocks, I think you're better off listening to Dave, as he is quite familiar with the Australian law concerning laser shows.
    Agreed, nothing better than experienced local knowledge in this area.

    Thanks again Adam, your helpful advice is very much appreciated

    Oh, and I did find that international standard document where you suggested

  10. #20
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    Thanks Mark for your information and advice

    Quote Originally Posted by Insanity View Post
    I reckon you will have plenty with the 12mm, it would take a fair bit of heat to distort that... 8mm would probably suffice and drop the overall weight of the projector significantly, which is an important factor if you are going to be loading the projector on and off lighting trusses.
    I've laid all the components out, considering all of the points raised in this thread. I will be drawing this out soon to verify, as well as probably building a prototype using some spare 6mm aluminium sheet (which I have lying around).

    I'm proposing a 2 shelf design; upper shelf for the PSUs and drivers, lower shelf with just the lasers and optics. Each shelf with a base plate size of 440mm x 400mm. I expect the housing will have an internal frame with sheet metal panels. The base would most likely be supported by this frame (on the outer edges at least).

    Given these dimensions and proposed design, do you consider 8mm would be sufficient? I agree and would like to keep the weight as low as possible.

    Quote Originally Posted by Insanity View Post
    I added a sealed optical area to my projector. Mine is all on one level, the optics on one baseplate sealed in an acrylic box with no fans, and the electronics on a second baseplate with fan cooling....
    Great looking work with that, I would like to do something similar. It doesn't look airtight though, is that/isn't that desirable? I'm assuming a design which allows a removable panel for cleaning and optics adjustment.

    Quote Originally Posted by Insanity View Post
    With the 635nm and 640nm thing, you can get very high powered 640nm lasers from Dave in Australia or Martin (Pelosh) in UK made by Kvant. I believe Laserwave might do some as well, again Dave, Stanwax or Gottaluvlasers can help there.
    Yes, perhaps for projector number 3 (or a later rebuild of this one). Until then, 635nm it is

    Quote Originally Posted by Insanity View Post
    Here is a comparison.

    A white beam with 635nm red


    Click image for larger version. 

Name:	DSCN0686.JPG 
Views:	74 
Size:	1.19 MB 
ID:	14463

    A white beam from a 640nm red.

    Click image for larger version. 

Name:	P1000330.JPG 
Views:	75 
Size:	2.18 MB 
ID:	14462
    Great shots and perfectly demonstrates the difference. I'm no optics expert, but I do wonder about reverse telescopes, using a beam expander in reverse and even an aperture/iris to cut out the fringe. Probably just some crazy thoughts and a lack of knowledge on my part I have seen a lot of info on the web about beam expanders, but nothing about beam "reducers".

    Quote Originally Posted by Insanity View Post
    I use only 600mw of 640nm in my 2.3watt RGB and it makes a beautiful white..
    What are the specs of each of the lasers you've used in this projector?

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