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Need help with laser project

Discussion in 'Electronic Design' started by Craig, Mar 21, 2007.

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  1. Craig

    Craig Guest

    I have a project, I am trying to convert the X/Y/Z (blank) signals from a
    circuit designed to output to a vector scan monitor and redirect them to
    laser either by galvanometer/PC interface/anything possible to active this..

    Can you help direct me to resources or the best way to do this?
    This is for a single laser output (one color).
    The problem also is that I want to increase the axis range dynamically so
    that I can project on a wall, building, anything....

    Thanks for any helpful suggestions!
    Anyone for hire to help do this???

    -Craig
     
  2. James Sweet

    James Sweet Guest



    There was a similar project a few years back, laser MAME which was an
    emulator of vector arcade games. The problem is that galvos have
    physical mass and inertia, so the characteristics are quite different
    than that of a vector monitor. If you can emulate the hardware on a PC
    that's probably your best bet. There won't be a simple hardware converter.
     
  3. Arfa Daily

    Arfa Daily Guest

    I seem to recall that Elektor magazine did an x-y laser projector a couple
    of years back, and that a kit was done for it. Might be worth you posting on
    their website forum. Also, the actual mechanics and drive electronics to do
    this are readily available at very reasonable prices form the likes of
    Maplin here in the UK. They are used for disco lighting purposes, and
    respond to the music, but as far as I know, the effect is achieved by having
    an x-y mirror unit driven by stepper motors. I would have thought that it
    would not have been terribly difficult to suitably scale and condition the
    analogue x-y drives for a stroke writing monitor, to suit the mirror drive
    circuitry of such a ready-made unit, and sub your laser into the optical
    path in place of the lamp unit.

    Arfa
     
  4. GPG

    GPG Guest

    It used a couple of DC motors to generate semi-random patterns using a
    laser pointer
     
  5. Rich Grise

    Rich Grise Guest

    Some of this stuff might be interesting:
    http://www.google.com/search?q="laser+light+show"

    And yes, I'm available. What's your budget? :)

    (just in case you're serious about hiring this out, the email in the
    "from" line is bogus - to get a real email, take
    (which is a spamdump) and elide ard.)

    Cheers!
    Rich
     
  6. Sjouke Burry

    Sjouke Burry Guest

    Open up a damaged cd or dvd player.
    It has a nice lens arrangement which you can
    use to move around/tilt a small piece of mirror
    you glue on top of the lens.
    Then feed the small coils with all sorts of
    signals, and have fun with it.
    As you are only changing the angles, just stay far
    away from the target, and you will get a nice big
    picture field.
    (Oh and don't you or other people look into the laser beam)
    For safety, you can make a small detection circuit,
    to check for the presence of AC voltage on the
    coils, and use that to switch on/off the laser.
    That increases your safety manifold.
     
  7. Sjouke Burry

    Sjouke Burry Guest

    Oh I forgot one way to do this very easily,
    glue pieces of mirror to two small loudspeakers,
    then bounce the laser form the first mirror to the
    next mirror, and use a stereo amp, and music to
    move the mirrors/speakers.
     
  8. Jim Land

    Jim Land Guest

    This was my initial thought: too much mass, too much inertia, slow
    response.

    But loudspeakers are really "linear galvanometers", and their frequency
    response is quite good. Might be fun to figure out how to change a mirror
    angle with an old speaker.

    Old hard drives used a moving-coil in a magnetic field to scan the sensor
    across the disk--another opportunity to turn an old part into an
    interesting experiment.
     
  9. Guest

    the vector crt signals are too fast by a factor of six or more for
    even the best galvos, you'd have to recode the source to add delays,
    considering, if this is a vector game, the vector generation timing
    and scaling is always partially hardcoded in hardware,so you have a
    BIG problem. Also crts don't have blanking points, buffer points,
    extra corner points, all needed by even the fastest galvos, and most
    vector systems, with the exception of a few that do sliding stroke
    writing,(ie charge a integrator to the new point voltage) return to
    center in between objects, the return to center is fine for a blanked
    electron beam, but it confuses the heck out of the galvos. btw, as
    you expand scan size, you need to slow down the scan rate.

    galvos have inertia,electron beams for practical purposes dont.


    the other way to do it is use a AO deflector pair, but thats
    megabucks.


    I know the fellows that did laser mame, and its not easy. plus if
    your using game code, its a most excellent way to get sued. Laser
    Mame passed the points from a emulated game to a pangolin card
    that
    drove the galvos, and that is probably the best solution. Galvos
    limit out at about 700 points in a image.

    if its military, like a flight simulator, start here:

    www.pangolin.com
    then
    www.camtech.com

    if thats not fast enough

    http://www.neostech.com/PDFs/ao deflectors.htm

    neos makes a nice 512x512 XY deflector, so does

    www.Intraaction.com

    probably Crystal technology and Brimrose do as well.

    none of the mentioned hard drive motors, modified speakers etc will
    get you anywhere close to the speed of a true galvo with feedback
    I used to earn my living doing vector graphics with lasers.


    Steve Roberts
     
  10. Rich Grise

    Rich Grise Guest

    I'd cut out the cone, and let the spider support the voice coil. Then, get
    a little mirror, mount it seesaw fashion, and couple the voice coil to
    one end of it. Your second mirror would have to be wider or taller than
    the first one, depending on how much deflection you're looking at.

    But people have been doing laser light shows for decades! Didn't I post a
    link earlier today to a google of "laser light show"?

    Good Luck!
    Rich
     
  11. By design, the lens does not tilt significantly. It moves up and down
    (focus coil) or side-to-side (tracking coil).

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  12. Lougspeakers don't change angle but only translate (at least
    ideally). Any angle change is a byproduct of non-linearities
    in the system.

    There are relatively inexpensive galvos that will do the X and Y at low
    speed.

    --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
    Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
    +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
    | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name AND either lasers or electronics is included in the
    subject line. Or, you can contact me via the Feedback Form in the FAQs.
     
  13. James Sweet

    James Sweet Guest


    That won't do what he's asking, for vector graphics one needs expensive
    high speed closed loop galvos and drivers.
     
  14. Lionel

    Lionel Guest

    [posted & emailed]
    A pair (one for X, one for Y) of mirror galvanometers is the standard
    way to do this, although they can be tricky to drive to useful speeds.
    I once built something similar 15+ years ago, but I obtained my galvos
    by scavenging them from the laser tracking mechanism of an obsolete
    laser-disk player, so I'm not sure where you'd buy them these days.
    Depending on your laser, the distances you're working with, & the
    amount of deflection you require, it might be possible to adapt the
    equivalent assembly from a DVD burner. (Some of the have very nice
    high power, visible red laser diodes built into a (possibly) suitable
    servo mech.)
    Do you just want to build one, or do you want to go into production?
    What kind of budget do you have to work with?
    Feel free to email me if you want to discuss this privately.
     
  15. A magnet to scan the field operate in the mhz range and is real
    complicated. The exact transform to operate as an x,y or z value may
    be operated and the circuit output behave oddly.

    If an x,y, or z value is desired to be applied to the laser the
    science is applied art.

    Here is what I would do to have fun.

    A scan coil is removed from the side of the CRT. All the wires
    overlapping in the exact geometric center may safely be spread apart.
    Making a hole thru which to pass the HeNe tube!

    What happens is as you request! And x scan causes the x modulation
    frequency of the HeNe , the y the y-mode and z the z-mode.

    So you have three channels to modulate with x.

    Apply the frequency to the circuit to cause frequency modulation.
     
  16. John Barrett

    John Barrett Guest

    What about a scan converter ?? sample the high data rate x/y/blank signals
    into a buffer with some vector/corner detection to "extract" the useful
    coordinates, then output a low rate stream to the galvo scanners, adding
    corner points to square things up -- DSP should be up to the vector/corner
    detection, and a microcontroller can handle the slow scan output. One of
    those DSP/MCU combos should be quite capable of the task.
     
  17. joseph2k

    joseph2k Guest

    Raster conversion with X and Y smoothed stepper motors (similar to existing
    multi-frequency monitors) sounds like the way to go. I could develop it,
    but can you afford me (and my team)?
     
  18. John Barrett

    John Barrett Guest

    spec was for laser galvo output -- raster scan conversion wont help with
    that -- gotta slow down the vector rate from CRT speeds to galvo speeds -- I
    dont even know where steppers come into this -- far too slow and too low
    resolution
     
  19. Guest

    Isn't thise really a 2D problem, not 3D?

    I've bought the mirror deflectors from bar code reader at the local
    fleamarket. Of course, that is only 1D.
     
  20. John Barrett

    John Barrett Guest

    the Z in this case is a TTL blanking signal -- turn the beam on or off while
    the scanners poition to the start of a new vector.
     
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