mrapple@quack.sac.ca.us (Nick Sayer) (06/09/91)
Let's say I was crazy enough to want to design and build a lazer-show controller. It's obvious that you use a pair of mirrors - one to shift the beam along the X axis, one to shift the beam along the Y axis. Fine. But those shows achieve fast shifting around. So they must have very fast, yet precise motors. Those motors aren't doing a raster scan, they use vector graphics - hence the fine control. So it's likely that a stepper motor would do the trick, perhaps something along the lines of those used as cylindar select motors in hard disks. So now the $64 questions: What sort of motors are capable of going that fast? Where can I get them? How much do they cost? -- Nick Sayer | Official Scapegoat for the | RIP: Mel Blanc mrapple@quack.sac.ca.us | MC68HC11 Mailing List. | 1908--1989 N6QQQ | To subscribe, send mail to | May he never 209-952-5347 (Telebit) | mc68hc11-request@quack.sac.ca.us | be silenced.
mcovingt@athena.cs.uga.edu (Michael A. Covington) (06/09/91)
How about moving the mirrors with a loudspeaker that has been modified in some way, e.g., pinioned in a particular place so that you will get angular rather than linear motion? -- ------------------------------------------------------- Michael A. Covington | Artificial Intelligence Programs The University of Georgia | Athens, GA 30602 U.S.A. -------------------------------------------------------
gandrews@netcom.COM (Greg Andrews) (06/09/91)
In article <kWhnZkR@quack.sac.ca.us> mrapple@quack.sac.ca.us (Nick Sayer) writes: >Let's say I was crazy enough to want to design and build a lazer-show >controller. > >It's obvious that you use a pair of mirrors - one to shift the beam >along the X axis, one to shift the beam along the Y axis. Fine. >But those shows achieve fast shifting around. So they must have >very fast, yet precise motors. > The REAL ones ($$$) use something my buddy calls "Analog Servomotors", which I think means "a beefed-up galvanometer". The drive rotates a shaft to turn the mirror. It reduces parallax in the mirror's movement over hinged-on-one-side techniques. If you're not overly concerned with large amounts of deflection, then you can use audio speakers (as another posting mentioned). They are reasonably linear through the central 10-20 degrees of deflection, and are cheap enough that failed experiments won't break the budget. Another possibility might be the head positioner mechanisms from hard disk drives. Obviously, voice coil types would be preferred over the stepper motor ones. (Guess what technology the "voice coil" drive was borrowed from!) -- .------------------------------------------------------------------------. | Greg Andrews | UUCP: {apple,amdahl,claris}!netcom!gandrews | | | Internet: gandrews@netcom.COM | `------------------------------------------------------------------------'
smasters@gmuvax2.gmu.edu (Shawn Masters) (06/09/91)
The method of using a speaker to drive a mirror position has been refined into what is known as a voice coil. You mount a mirror on the end of the voice coil, so that when it's extended it has a different angle of reflection. This is used in many models of laser disk players to position the beam on the disc(in fact I got my first x y laser display unit from a friend that tore down a Dragons slayer(sp?) game). Another source is the stepper mechanisms out of some hard drives. The problems you find is that the coil vibrates, and there is a bit of jitter if it's making discrete motions(from point to point). You can get it to make really neat paterns when hooked up to sinusodial source on both x and y, but these tend to be fairly easy on the coils, unlike most animation by laser. The other problem is that I've never seen a voice coil fast enough to draw a diagram that the eye would catch whole. You can get them to do circles, but I think that would die on something more demanding like a square. Of course, what you mentioned about the speaker is great for home stereo systems and certain types of music:-). Shawn Masters smasters@cns01.gmu.edu
digex@world.std.com (doug e humphrey) (06/09/91)
What you want are called Galvonometers (galvos for short) and where to get them is easy; the number one supplier for such things as affordable (sort of) galvos is General Scanning located in Watertown MA. Their cheapest is something like $330 or so, scans only one axis (you use two of these together to get X-Y) runs around 20khz I think (doing this from memory) and settling time depends on the setteled accuracy that you need. Motors do not do this kind of stuff well, and they are no the technology that is employed. GS has the basic pattents of some special capacitive coupled techniques that allow for very low mass, fast reacting structures to move the mirror structure, and good control to make sure that you do not overshoot the position, etc. You are about to step off the edge into some pretty expensive hardware if you really want to get into this. A good galvo and control setup for laser shows is around $10,000 to start, and more than that for something that you would do a "real" show with. Note that this does not count the lasers! Build your own can save you some money, though what you build will not be up to the standards of the commercially produced gear in all likelyhood, but it takes a *lot* of time, and in the end there is just no such thing as building your own galvos that can perform to the point where they are usable in a laser show. GS locks their dumpsters up, because they know that there are people in the Boston area lurking around trying to get the old, broken, maybe out-of-spec galvos that they no doubt throw away. Not for industrial spying, but because some of us can not afford to pop real bucks for galvos for our lasers. By the way, what are you going to do for lasers? I might have a nice Spectra Argon for sale, pumps easily 100mw, I can give you plans for a good power supply, or you could buy from MKW and pay some real money! Good luck. Doug Humphrey
grege@gold.gvg.tek.com (Greg Ebert) (06/10/91)
In article <kWhnZkR@quack.sac.ca.us> mrapple@quack.sac.ca.us (Nick Sayer) writes: >Let's say I was crazy enough to want to design and build a lazer-show >controller. > [...] Some off-perpendicular mirrors mounted on several (inexpensive) DC motors work great. You 'cascade' the motors so that the beam strikes 3 or 4 motors before projecting onto your wall. We used some smashed mirror pieces (about 1/2" diameter). Get some pots so you can vary the motor speed. For $10 at Radio Snack you can make a pretty good display. To mount the mirrors, cut some 3/8" dowel, sloppily drill a hole through the center, press onto motor shaft, and glue-on the mirror. Very easy. The shapes resemble something made with a Spirograph (remember those ?) : complex elliptical forms. Subtle changes in motor speed make vivid changes in patterns. The smoothness and patterns are especially pleasing to the eye, even more-so if you are a bit inebriated. We also glued mirror fragments to speakers in an attempt to syncronize to music, but the motion is too random. (Optional) Pink Floyd backgound music, perhaps a few 6-packs....
bame@hpfcbig.SDE.HP.COM (Paul Bame) (06/11/91)
Meridith Instruments (a semi-surplus laser-supply company) often has galvos for sale - check out the advertiser index in Radio Electronics or Circuit Cellar Ink magazines. -Paul Bame bame@hubble.sde.hp.com N0KCL
mzenier@polari.UUCP (Mark Zenier) (06/11/91)
In article <kWhnZkR@quack.sac.ca.us> mrapple@quack.sac.ca.us (Nick Sayer) writes: >Let's say I was crazy enough to want to design and build a lazer-show >controller. See "Elektor Electronics USA" for May and June 1991. These magazines have a two part construction article on a laser light show using mirror galvanometers. (Of course it's probably a different date for one of the other editions of Elektor.) Elektor Electronics is a european electronics magazine, and Elektor Electronics USA is a new edition published by the "Audio Amateur" and Old Colony Sound Lab folks. The kit is from ELV France B. P. 40 F-57480 Sierck-les-Bains FRANCE Elektor Electronics USA P. O. Box 876 Peterborough, New Hampshire 03458 Mark Zenier markz@ssc.uucp mzenier@polari.uucp
Mike_Diack@kcbbs.gen.nz (Mike Diack) (06/12/91)
How about the focus/tracking mechanism out of a CD player ? good 2 axis movement & very fast.
frankb@hpsad.HP.COM (Frank Ball) (06/12/91)
/ Mike_Diack@kcbbs.gen.nz (Mike Diack) / 1:23 pm Jun 11, 1991 / *How about the focus/tracking mechanism out of a CD player ? good 2 axis *movement & very fast. ---------- I bought an old laser disc player surplus for $70 (no there aren't any more). It has a He Ne laser and X-Y deflection mirrors. The mirrors were controlled by a complex feedback loop, but that circuitry that is not usable (for anything but the origional function as a laser disc player). There were some polorizers, splitters, and lenses that I ripped out. The mirrors have voice coils on them (8 ohms), and I was able to use the origional deflection amplifiers. I can get about 200 Hz (it's rolling off by this point) of bandwidth out of the mirrors. It looks ok with music, more bandwidth would be nicer with some types of music, it's plenty for other types. The bandwidth is much to limited for any type of fancy graphics displays. Frank Ball frankb@hpsad.HP.COM pyramid!hplabs!hpsad!frankb
hbg6@citek.UUCP (John Schuch) (06/13/91)
In article <kWhnZkR@quack.sac.ca.us> mrapple@quack.sac.ca.us (Nick Sayer) writes: >Let's say I was crazy enough to want to design and build a lazer-show >controller. > >scan, they use vector graphics - hence the fine control. So it's >likely that a stepper motor would do the trick, perhaps something Nope, not fast enough. >What sort of motors are capable of going that fast? Where can I get >them? How much do they cost? You are looking for galvomotors. They are basicly a high horse-power meter movement. Meridith Instruments in Phoenix sells used ones for about $75 each. ( quite cheap compared to new ones ). Email me if you need the address. They also have a lot of neat used laser stuff. John ..................................................................... Have fun, Play nice, Don't fight. OK Dad. ..................................................................... John Schuch - Motorola Inc., Computer Systems Division (602)438-3008 All opinions expressed are mine and not Motorolas, their loss. .....................................................................
tedwards@aplcomm.JHUAPL.EDU (Edwards Thomas G S1A x8297) (06/15/91)
In article <12530@qisoff.phx.mcd.mot.com> hbg6@citek.UUCP (John Schuch) writes: >In article <kWhnZkR@quack.sac.ca.us> mrapple@quack.sac.ca.us (Nick Sayer) writes: >>Let's say I was crazy enough to want to design and build a lazer-show >>controller. >You are looking for galvomotors. They are basicly a high horse-power >meter movement. Meridith Instruments in Phoenix sells used ones for There is a book called _The Laser Cookbook_ which describes some circuits for driving galvos (usually just a 741 driving a complimentary pair of medium-power transistors). For those of you designing a laser show, I reccommend the AD7226 quad 8-bit D/A converter. It saves you from having to have a large number of D/A chips, opamps, and latches since it has all of that built in. (i.e. voltage mode D/A). -Tom
miker@polari.UUCP (Mike Ranta) (06/15/91)
In article <1840048@hpsad.HP.COM> frankb@hpsad.HP.COM (Frank Ball) writes: >I bought an old laser disc player surplus for $70 (no there aren't any more). >It has a He Ne laser and X-Y deflection mirrors. The mirrors were controlled This is a new one to me. Every CD player I've ever seen uses an infrared laser diode. A HeNe laser would be large, expensive, hot and limited in life. Also, there are no real usable mirrors for the purposes of a light show. The laser diode, receiver diode, optics and focus/tracking servos are usually all together in an assembly about .5" square! The only other component from a player is the positioning servo that moves the above assembly along the disk. It's MUCH to slow for this application.
rainer@boulder.Colorado.EDU (Rainer Malzbender) (06/17/91)
In article <4449@polari.UUCP> miker@polari.UUCP (Mike Ranta) writes: >In article <1840048@hpsad.HP.COM> frankb@hpsad.HP.COM (Frank Ball) writes: >>I bought an old laser disc player surplus for $70 (no there aren't any more). >>It has a He Ne laser and X-Y deflection mirrors. The mirrors were controlled > >This is a new one to me. Every CD player I've ever seen uses an infrared Laser disc player doesn't mean CD player. A friend of mine used an old laser disc player to make a 3D digitizer, and I'm fairly certain it also had a HeNe and mirrors in it. -- Rainer Malzbender Dept. of Physics (303)492-6829 U. of Colorado, Boulder rainer@boulder.colorado.edu 128.138.240.246
rainer@boulder.Colorado.EDU (Rainer Malzbender) (06/17/91)
In article <4449@polari.UUCP> miker@polari.UUCP (Mike Ranta) writes: >In article <1840048@hpsad.HP.COM> frankb@hpsad.HP.COM (Frank Ball) writes: >>I bought an old laser disc player surplus for $70 (no there aren't any more). >>It has a He Ne laser and X-Y deflection mirrors. The mirrors were controlled > >This is a new one to me. Every CD player I've ever seen uses an infrared >laser diode. A HeNe laser would be large, expensive, hot and limited in Laser disc player doesn't mean CD player. A friend of mine used an old LDP to make a 3D digitizer, and it also had a HeNe and scanning mirrors. -- Rainer Malzbender Dept. of Physics (303)492-6829 U. of Colorado, Boulder rainer@boulder.colorado.edu 128.138.240.246
rainer@boulder.Colorado.EDU (Rainer Malzbender) (06/17/91)
Oops. Sorry about the duplicate, News on this machine is approaching senility. Rainer Malzbender Dept. of Physics (303)492-6829 U. of Colorado, Boulder rainer@boulder.colorado.edu 128.138.240.246
andywang@power.berkeley.edu (Andy Wang) (06/24/91)
mrapple@quack.sac.ca.us (Nick Sayer) writes: >Let's say I was crazy enough to want to design and build a lazer-show >controller. Silicon Valley Surplus has a "home laser light show" controller in their ~June catalog. In short, the features are: 2 lissajous oscillators 2 galvos 20 deg vert swing, 180 deg horiz, 10 deg pattern pattern rate 100hz 2 audio inputs computer (parallel port) interface with D/A converters No laser included Medium-difficult assembly $99.00 They also have a bunch of other cool stuff, especially stepper motors. The address is: 1273 Industrial Parkway W. Bldg. 460 Hayward, CA 94544 Andrew andywang@power.berkeley.edu