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Thread: Through a scanner incoherently: Newbie Scanner project and questions

  1. #1
    Join Date
    Aug 2010
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    Default Through a scanner incoherently: Newbie Scanner project and questions

    Hello

    Iím an undergrad that recently became a grad student in physics. I was asked by a professor to put together a laser system that projects images (in this case the lab name). He said that systems like this is easily purchased and said I had 200 USD. My first problem is that my undergraduate was chemistry. After researching the systems I found that basic scanner systems cost around ~150 USD.

    I went to Lasershow Parts and got directed to this by customer service:
    SCANLSP-20 20k Scanner Laser Show Galvo for DPSS Argon - eBay Industrial Lasers, Lighting Lasers, Industrial Supply MRO, Business Industrial. (end time 03-Sep-10 20:34:06 AEST)

    Now I was told along with the $200 I had a HeNe laser and a power supply available to me. The HeNe does not have the ability to be rapidly switched on and off (as one would have to have in drawing separate objects). I told him this. He insisted that no system ever did this (as it would damage the laser). I am aware this is not true. He flatly said I needed a mechanical shutter. I did not push him on the issue due to his demeanor.

    I am aware this will cost more than $200. I need to know if I have all the supplies and thus costs correct.

    Here is where Iím at:
    Tutorials I know of:
    http://laserpointerforums.com/f47/so...ial-40569.html
    http://laserpointerforums.com/f47/ne...ner-44748.html
    http://laserpointerforums.com/f47/sc...ons-45739.html
    http://laserpointerforums.com/f39/fs...ner-51536.html
    The dmx card, first run


    Materials:
    20 Kpps scanner DMX
    SCANLSP-20 20k Scanner Laser Show Galvo for DPSS Argon - eBay Industrial Lasers, Lighting Lasers, Industrial Supply MRO, Business Industrial. (end time 03-Sep-10 20:34:06 AEST)

    Servo for shutter:
    Iím not sure if this is adequate, but my idea was using a servo to cut off the laser beam whenI needed it off. I tried finding a camera shutter but it would look like I would have to disassemble a camera to get one.

    Control Board for servo:
    Lasershow Parts - Single channel DMX512 RC-Servo driver

    Futabaģ S9070 Programmable Mini BB Servo
    It appears that all their servos have a hookup to receive commands so I would either just wire into where receive or add a radio transmitter.

    USB to DMX
    ENTTEC - DMX USB PRO
    ENTTEC - DMX USB ASSEMBLED AND TESTED IN METAL HOUSING

    Pangolin Quick show demo

    Here are my questions:
    Is this all I need?
    Is the servo fast enough?
    Should I just go DAC? I have no idea what this means really but all the tutorials I have found use DAC. The DMX ones are very vague. I have heard bad things from forums that DMX is simpler and does not have the effectiveness as DAC.
    Is the wiring as simple as I think it will be?

  2. #2
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    Jul 2006
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    Default

    hey chalco-

    i cant respond in great detail, as i am on my way into a meeting.

    $200 to make this work is going to be VERY tough.

    you are going to need (3) scanners. (X, Y, Z). I dont think a servo is going to be anywhere remotely near fast enough to "blank" (turn laser beam on and off) properly to draw a semi-decent graphic or text. the "Z" axis scanner will be your blanking scanner. however, you are going to need software/hardware to control this.

    LSP's 20K scanners should be fine for what you want to do, but you still are going to need a 3rd blanking scanner. Or just purchase a low power laser that has TTL blanking. despite what your know it all professor says, turning lasers on and off rapidly is quite possible and in fact the norm these days.

    You can get 50mW-100mW green or red lasers with TTL mod (or even analog modulation) for next to nothing these days. maybe $50-$100. with the laser being able to be blanked, there will be no need for a third scanner.

    Now all you need is a DAC. there are many free softwares out there, however you need some sort of DAC. something to take the software info and send it to the Laser system. there are sound card DACS that are VERY affordable and some of the free software is Spaghetti, laserboy.

    Obviously the best way to try and do this would be with a pangolin FB3/Quick Show system. this will ruun you ~$600. and it seems as if your budget does not allow fo this.

    -Marc
    http://www.laserist.org/images/ildalogos/ILDA-logo_colored-beams_Corporate_150w.jpg

    ILDA- U.S. Laser Regulatory Committee

    Authorized Dealer for:

    • Pangolin Laser Software and Hardware
    • KVANT Laser Modules & Laser Systems
    • X-Laser USA
    • CNI Lasers
    • Cambridge Technology & Eye Magic Professional Scanning Systems

    FDA/CDRH Certified Professional LuminanceRGB Laser Light Show Systems


  3. #3
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    Washington.
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    Default

    i would be able to offer a 60mw 532nm with ttl (i believe) modulation within the next week or so... for dirt cheap too.

  4. #4
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    Aug 2010
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    Thanks.

    So basically go DAC get 3 galvos and control boards, X-Y mount, something for switching mount, sound card DAC, and correction amp is what I need(http://www.photonlexicon.com/forums/...696#post139696).

    I need a seperate powersupply for the glavos also. Is googling "multi voltage switching power supply" and going with whatever looks similar fine?

    Anything else?

    http://laserpointerforums.com/f39/fs...ner-51536.html
    Click image for larger version. 

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    Here I see card in the middle and the power supply-ish box I don't recongize and in the thread the author references a sepearte power supply. What are these? I think one is a power switching power supply, and the other a DAC soundboard.

    Also:
    Click image for larger version. 

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    He lists this as a $10 usb soundcard. Is 300evil's card a these 2 parts combined, or do I need evil300 card and a seperate DAC card?

    Also in the linked thread he mentions something about flexmod drivers. I'm asking to make sure these are diode power supply related and not a concern for me.

  5. #5
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  6. #6
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    Smile

    Hey Chalcogenide;

    Welcome to PhotonLexicon! You're in the right place, friend. We can certainly help you with this project. By the way, where are you located? You didn't fill out your profile information... Would be nice to know if someone is local to you who could offer direct assistance.

    Your professor is clearly behind the times. There are several options that he hasn't thought of. However, he is correct about one thing: You will not be able to turn the Helium Neon laser on and off fast enough to accomplish the effect you're trying to do. It won't really damage the unit to try this, it just won't work.

    All gas lasers have to be modulated externally. These days, that's typically accomplished either with a third scanner (so-called scanner blanking),or with an acousto-optic modulator (AOM). An AOM is essentially a crystal transducer that, when fed an RF signal, sets up a standing sound wave within the crystal. This standing wave creates areas of varying density, making the crystal act like a diffraction grating, which "steers" the beam slightly to one side or the other. (Here's a link to a good primer on the technology.) AOM's are very expensive, however, so that's not going to work for your application.

    Scanner blanking is the other option for blanking your HeNe laser. Basically the mirror on the blanking scanner sends the beam to a retro-reflector, which sends it back to the mirror on the blanking scanner, and from there to the other scanners which "draw" the image. When the blanking scanner mirror moves just a little bit, the optical path changes enough that beam will miss the other scanners, so you have no output. Here is a video showing what this arrangement looks like. (Video Credit to our own 300Evil.)

    However, to set up a system with scanner blanking is still costly and rather cumbersome, as you have to purchase a third scanner, and the mount, and the retro-reflector, and then you have to align it all. In your case, I think you would be better off using a cheap solid state laser (that is, a red laser diode, or a DPSS green laser) as your laser source, and forget about using that lab HeNe. Solid state lasers can be modulated directly, and they can be modulated *very* quickly. (Several orders of magnitude faster than is required for laser light show uses.) They're also dirt cheap, and as an added bonus they will be brighter than that HeNe as well!

    A simple 150 mw red laser diode with a modulating driver will cost you less than $60 if you buy it off the shelf, and you can build one for even less than that. With a solid state laser, you can turn it on and off as needed to create your images. This is the route I would take if I were you. Forget the lab HeNe and go solid state. (A 50 mw green laser with modulation, which will appear even brighter to the eye, costs just $65.)

    Finally, there is another piece of the puzzle here. You need some way to generate the signals that will be sent to the scanners to "draw" the image. The DMX board that comes with the scanners you selected has a bunch of pre-programmed images, but you will not be able to edit those images. (That USB-to-DMX interface you were looking at will only be useful for switching between those stored images on the DMX board; you can't program new images via DMX.) So the DMX board won't allow you to display your laboratory name or logo. For that, you need some custom laser show software (to create and display the artwork) and a laser show controller that will take the digital signals from your computer and convert them to analog signals that the scanners will use to "draw" the image.

    Fortunately, there is a cheap solution here as well. The easiest option would be a modified computer sound card (as a controller) and some free (or nearly free) software to run it. On the sound card, you'll need to remove the DC-filtering capacitors on the output, and you'll also need to add a correction amplifier to raise the signal levels to the proper voltages for the scanner amps, but otherwise it's a straightforward build. Figure around $100 total for the sound card and correction amp, or less if you build your own correction amp from scratch.

    Then you'll need software to run it all. And there are a few inexpensive solutions out there. Laserboy software is free, and it will allow you to create .wav files that you can play back through your modified sound card (using mediaplayer) to run the scanners. Or you can get a copy of Spaghetti, which is a full-featured laser show creation and playback tool, for just $50. Our own JohnYayas (AKA Gary Harper) is the author of Spaghetti, and he can assist you with any problems you may have with the software.

    But the bad news is that even if you buy the cheapest scanners you can find on e-bay (something like these), and you buy a cheap USB sound card (this is the one most people use) and a sound card correction amp, you're already over your budget. So yeah, you're going to need to stretch the budget a bit higher than $200.

    But so long as you're OK with spending the extra money, then you can *definitely* do this. The scanners you picked (The LSP-20's) will serve you quite well. They offer the best performance in that low price category, in my opinion.

    I would suggest going with either the red or green laser linked to above, unless someone here on PhotonLexicon makes you a better deal. And I *strongly* suggest you opt for the Spaghetti software. That will be a *very* nice solution that will really knock your socks off. (Spaghetti gives you a lot of bang for just $50.)

    Hooking everything up is fairly straightforward, and we can help you with that if you get stuck. But it's not hard. Once you have the components in hand, connecting them is a matter of a few hours work at most.

    Botton Line: I think it's worth it to expand your budget a bit (even if it comes out of your pocket) so you can blow your professor out of the water with what you end up making...

    Adam

    PS: The Pangolin Quickshow demo software you listed will not help you at all. That software will only work if you also have the Flashback 3 laser show controller. In fact, the software and controller are sold as a package, for around $600 if memory serves. It's outstanding software (world class, even), but it is useless by itself. You will not be able to use it for this project unless you decide to purchase the Flashback 3 controller in leu of using a modified sound card and correction amp as your controller. And given the budget you had in mind, I don't see this happening.

    PSS: The servo you selected can be used as a safety shutter, but apart from that it won't be of any use for blanking. (It's not fast enough.) Also, if you go with the solid state laser, you can rely on the direct modulation for safety and omit the shutter. (If you're not sending a signal to the laser, it will be off.) Granted, a safety shutter is still nice to have, but it is not, strictly speaking, a requirement when dealing with solid state lasers.

  7. #7
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    Toronto, ON, CANADA
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    Default $200 is more than enough

    So you want a laser system that projects images (in this case the lab name). Great, you can do this for under $50 and spend the rest of your budget on beer. See:

    http://www.instructables.com/id/Laser-Image-Projector/

    Have fun!

  8. #8
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    Cool

    That is a static projection. What you've essentially got there is an overhead slide projector with the lamp removed and a laser added as a light source. That's not the same thing as moving a static beam around to "draw" a vector-artwork image with a laser though.

    Still a very cool projector, to be sure, but I'm pretty sure that's not what his professor had in mind...

    Adam

  9. #9
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    I don't mean to hijack the your thread Chalcogenide, you just asked a lot of the questions I've been searching for answers to. If I should start a separate thread, just let me know.

    I was looking at these and just getting a feel for what parts I'm going to need...

    http://cgi.ebay.com/Galvo-scanning-s...efaultDomain_0

    In regards to the correction amps, I've seen the Audiolase offered by 300Evil here and also the unit from LaserBoy. This is just my ignorance so no offense meant to anyone but there is a significant price difference and I don't know why. Can anyone help me out with that?

    Also, since I'm asking the neophyte questions anyhow, when looking for the laser and driver, what is the difference between the ttl and analog? Also, could pretty much any laser module be connected to a FlexMod P3?

    Howie

  10. #10
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    Smile

    Quote Originally Posted by Howie View Post
    In regards to the correction amps, I've seen the Audiolase offered by 300Evil here and also the unit from LaserBoy. This is just my ignorance so no offense meant to anyone but there is a significant price difference and I don't know why.
    Mostly it's in the cost of the parts that 300Evil uses. They're more expensive than the one's on the laserboy correction amp. How much of a difference does it make? That's your call, but I have yet to get my Laserboy correction amp dialed in correctly. (Yeah, even though I have three other DAC's including a Pangolin LD-2000, I just had to have a sound-card DAC too!) I haven't tried the Audiolase, however.
    when looking for the laser and driver, what is the difference between the ttl and analog?
    Good question! TTL is like a light switch. You get on and off, nothing else. Analog is like a sliding dimmer switch. You get a smooth range of brightness from full off to full on, and all points in-between.

    Analog is *far* superior to TTL. With 3 TTL lasers (red, green, and blue), you have a maximum of 7 colors. (Well, 8 if you count "black" as a color.) But with analog, you get 16.7 million colors, which is more than the human eye can perceive anyway. Analog color will give you beautiful color blends like you'll see in this show. (The video doesn't really do it justice, but you'll get the basic idea.)
    Also, could pretty much any laser module be connected to a FlexMod P3?
    Yes and no. The Flexmod P3 can drive most any laser diode, including the pump diode on a DPSS design, but the TEC circuit on a TTL-DPSS laser may not be designed to support analog modulation. (Many TTL-only lasers just flip the TEC to max current when the diode turns on.) So adjusting the TEC to function properly with an analog driver like the P3 might require you to replace the TEC driver as well.

    Adam

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