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Thread: Need help picking power requirments for homemade RGB scanner

  1. #1

    Default Need help picking power requirments for homemade RGB scanner

    Hi Guys,

    As a bit of a science project and to give me something to do with the kids now winter is closing in I am going to TRY and build a small RGB scanner.

    The scanner is for home use to just explore optics and have fun with the kids making shows. Most of the fun will hopefully be in making the thing. It will not be used for clubs, raves, large events or the Eagles comeback tour but it may be used at a school show and tell as well as projecting stuff on the side of my house at halloween and Christmas.

    I have read a few post where the laser ratios were explained i.e. 4:2:1 and I have also read that you should base the whole thing on the power of your red and work down.

    So far so good, but now is where I get really confused and that is with the red. The red comes in different wave lengths 635nm, 660nm and 671nm. From what I understand the 635 will be brighter at the same power outputs of the other 2 but at the expense of a fatter beam. 671 is DPSS and has a tighter beam but costs more. The MaXYZ units are 660 and seem popular.

    So my question is for a home made unit that will be used as described above will a 224mW 660nm be a good start for a base unit? Remember this is for fun and I want to try and keep cost as low as possible. So if I can get away with a lower power unit then the MaXYZ then great.

    I would like to utilise analog blanking so we can experiment with colour mixing etc but it is not essential if that makes it cost prohibitive. Ideally I would like to buy a set of 3 lasers off of one suppler.

    If anyone can help me or has any suggestions on a good budget starter set for the RGB lasers that would be great.

    Many thanks

    XG

  2. #2
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    Default

    No actually the ratio is based on Green. And then you calculate the rest. 4x1x1 is for 650nm red. 8x1x1 is for 671nm red. 2x1x1 is for 635nm red. So for 224mw 660nm you will need 60 mw green and 50 mw blue. But I would say
    100mw for green and 50mw for blue.

    For suppler go with lasershow parts. Dave/Aijii. They are here on the board. You can read their's review in seller review section.

    50mw blue CNI http://www.lasershowparts.com/store/...d&productId=45

    100mw green CNI
    http://www.lasershowparts.com/store/...d&productId=36

    Why those 2?
    First the price difference between those and lower power ones is very low.
    Second you will not find a lot of lasers lower then those.
    And the last they are CNI. Biggest and Qualitiest Laser supplier from China. They will last a very long time and give you up to 20-40% of extra power. So your 50mw blue will probably give up to 75mw of visible blue!

    MaXYZ....he is here on the board. You can ask him a question directly.
    I hired an Italian guy to do my wires. Now they look like spaghetti!

  3. #3
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    Hi XG

    glad you are getting into it .... and hope you enjoy your first projector

    just a word of caution ... you said ...
    but it may be used at a school show and tell
    I have been involved with profesional shows, and the last place i would ever take my Laser is a school, the reason being is that you are on local council / authority property and there are very strict regulations what can and cant be done on a school premises, also be wary of the "Wrath of the Parent" as little jimmy goes home and tell mummy that they had lasers at school today and six months later while hes on a routine visit to the opticians mummys told that his eyesight is poor she thinks Hmmm maybe it was that man and his lasers,

    im sure you would have alot less hassle doing a show in a nightclub

    Dont want to sound like the laser police, but for me a school is not the best place to show off you laser

    oh and make sure your kids have the same respect for lasers as you would .. dont want them learning brail at an early age

    God, i do sound like the laser police

    anyway this is detective inspector Banthai saying "allo allo allo"

    all the best ... Karl

  4. #4

    Default

    Thanks for the advise guys.

    @Dr Laser thanks for the links and I had seen those before. I think they are out of my budget for a science project If anyone has other options? Maybe Lasever?

    @Banthai Yep I agree. Maybe the show and tell was not the best example of the final use for the scanner I was just trying to get the point across that this is a budget system so don't spec me the best or even the best of the best.

    Cheers
    XG

    **Edit**
    Do I even need that much power for the type of system I want to build? i.e could I get away with 100 Red : 50 Green and 25 Blue. As I say this is mainly for the house so it will be running on a wall 10 foot x 10 foot indoors and if I did project on my outside house wall at Christmas that is only 30 foot x 40 foot.

  5. #5
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    Lasever... The problem with it was "crystal chamber contamination" and temperature control. The niobate lithium crystal have to be sealed very well and kept in proper temperature conditions. Otherwise the crystal will suck the moisture from the air go off and virtually die. Only recently those issues were addressed and apearently were solved. But we need some more time to make sure Lasever lasers will live a good long life. Lasever's red modules are ok.

    BTW xgeek...the easiest way is to tell us your budget. Then we can be @ better service.
    I hired an Italian guy to do my wires. Now they look like spaghetti!

  6. #6
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    I use mine indoors and on the side of my house. I have a 50mw green and it is plenty strong enough. In fact, sometimes it is too strong because it illuminates the room too much. I have a red around 165mw right now and it matches the green just fine. I don't have a blue yet because they are so expensive.

  7. #7
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    First: Heed advice from "Inspector Banthai" regarding lasers, schools and children. There are CDRH (FDA) variences required for public shows in the US-- and kids WILL look directly into the beam..Very Bad things could happen.. but.. sounds like fun If youre new to lasers they are not as safe as the general public thinks, unless waving around a class II and not staring into it..

  8. #8

    Default

    Thanks guys,

    I am new to scanners and fairly new to lasers. I only have a few pointers greens and red. The most powerful is 115mW as measured by Nova lasers. I understand the basics and have separate safety glasses for the green and red lasers.

    I really don't want this thread to turn into a safety lesson although I do understand your concerns and I thank you for warning me. I will now not take this into a school for show and tell and will only us this at home and on an outside wall.

    As to my budget. Well I don't have a fixed budget except I would like a system that does the basics without me selling my new born.

    By the looks of it I may have to drop the blue and add that in after everything is going as that seems to be the killer on cost at the moment. I was hoping that a company would do a starter kit of 150mW 660, 75mW 532 and 40mW 473 for around the $800 mark

    Cheers
    XG

  9. #9
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    Post in 'Buy/sell /trade' section and I'm sure you can find that greenie. Maxyzmodules -660nm 225mw are $2 hundred and something last time I checked and the blue I'm waiting on too.. . I'm keeping my eyeballs peeled to the CNI group buy thread - The safety thing comes to all who enter this forum unless they state "I have an argon Lexel 88" or ALC 60X or something like that in advance.

  10. #10
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    Cool

    The color ratio's that Dr Laser posted are close, but you'll want more blue than green if you want proper balance. The human eye is 2.4 times more sensitive to 488 nm blue than it is to 532 nm green. That sensitivity falls off even more as you go higher in the blue spectrum. So if you're thinking of using a 473 nm DPSS blue, then ideally you'd want somewhere around 2.6 times as much blue as green. However, in practice most people (myself included) can't afford that much blue. But to your best to get as much blue as you can. A 1 to 1 ratio of blue to green will work, but it will be green-heavy. (I'm running 1.5 blue to 1 green, and I wish I had more blue. I've got my green turned down to get my color balance back in line.)

    If you use 635 nm for your red, you will need a lot less of it. As evidenced by our *second* head-to-head test between two projectors (first at SELEM 2007, and second at FLEM 1.5), when we had one projector running 635 nm and one running 660 nm red, once again we saw that 635 nm appears roughly 5 times as bright to the human eye as 660 nm does.

    The problem with 635 is that 1) it's more expensive, and 2) the beam is fat. So 660 nm is a good compromise for the hobbyist. 660 is cheap, the beam spec is decent, and you can still get enough of it to make a decent white. 200 mw of 660 is a great starting point.

    As far as which way to work the numbers, while everything is REFERENCED to green (that is, green is always considered the 1X power level), it is very smart to start with red and work backwards. Here's why: If you work it forward you can end up with a projector that you can't afford. Say you start with a 200 mw green laser. Pretty soon you'll soon discover that you'll need nearly 2 watts of 660 nm red to balance it. But 2 watts of 660 nm red is going to be *incredibly* expensive, and also very cumbersome to boot. (Will likely involve multiple diodes, mirrors, PBS cubes, and some sort of collimating optics.) Not the sort of thing a budding laserist is counting on for his first projector.

    Red is usually the most limiting factor in projector design because there are so many things that can prevent you from attaining your goal with red. (Multiple diode complexity, high cost, large beams, human eye's low sensitivity to long wavelengths, etc) Blue is the second limiting factor, though it's due to just a single attribute: high cost.

    So by starting with red, you already know your limits in terms of power, cost, and availability. Then you work back to blue. Blue lasers are available in lots of different power levels, though they are expensive no matter what. Finally, with those two lasers decided upon, you select your green so you have enough for decent color balance. If you go with analog blanking, you can bump up the power of the green a bit so you'll have extra punch for beamshows, but if you're going with TTL it's better to keep the color balance pretty close.

    Now, if you *really* want to get started right away, Astroguy has a starter kit that he's selling for $1200 that is quite a bargain. He's got a 60 mw blue, a 50 mw green, and a 200 mw red, plus a set of 30 Kpps scanners, plus all the mounts and dichros you need to mix the beams from the three lasers to make white. He's even throwing in an optical plate to mount everything on. Plus he's already tested everything so you know it will all work. (Of course, you still need to mount everything and wire it all up, plus you need a controller and some software to run it...)

    I *was* going to buy this kit from him to build a second RGB rig, but after my house got broken into I don't have the cash. (Literally - the thief made off with a grand in cash that was going to be the down payment on a car! Bastard...) But he's offering it to PL members for the same price he was going to sell it to me for. See his thread in the for sale section, or just send him a PM.

    EDIT: Looks like I was off a bit on the power of the lasers. The green is actually making 135 mw. See this thread for details.

    Adam
    Last edited by buffo; 10-24-2007 at 18:58.

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