[kap4001] built what has to be the simplest laser scanner possible. It’s two servos strapped together with zip ties plus a 5V laser module. They’re connected to a Pololu serial servo controller. The laser is pulsed by switching the DTR line. You could use it to draw images like the one above… except that’s an 85 second exposure.
i would think it would be better to control a mirror through servos. then you could use whatever size laser you want, plus it would probably be faster.
on second thought, what if you used a rotating mirror to spread the beam out horizontally (think laser barcode reader), then a servo to scan vertically? then you could turn the laser on and off to display a picture. with a powerful enough laser it could be used to project images on buildings even…hmmm.
Posted at 9:12 pm on Dec 8th, 2008 by matt
http://heim.ifi.uio.no/haakoh/avr/
Scroll down.
Simpler, imo, and takes less than 85 seconds a frame.
Posted at 9:18 pm on Dec 8th, 2008 by N256
hard part is that your standard ol’ solid state lasers don’t lase very quickly–you can modulate them at relatively high speeds, but you’ll lose a quite a bit of contrast.
Posted at 10:17 pm on Dec 8th, 2008 by threepointone
threepointone: clearly, that’s what rubies are for. real men (and women) use proper ruby lasers
Posted at 11:13 pm on Dec 8th, 2008 by nick
Though, if you did it with a couple lasers, instead of just one. Then you rotate through them, that should decrease the delay a little bit. At least I think…
Posted at 11:19 pm on Dec 8th, 2008 by Ryan
Its a cool start but Those servos can never twitch fast enough.
Even stepper motors hit there limit and produce some jerky results.
Galvo’s are really the only way to go for full twitch!! Galvos are pretty easy to build from scratch hacking out speaker coils and the like. Use 2 bits of broken cd or a bit of first surface mirror from an old photocopier.
For a clean image scan rate and pulse speed are obviously the key elements. Even big powerfull RGB show lasers are pretty lame when its comes to producing a clear picture. But in the last 5 years the prices have fallen and it seems that dodgy stepper driven green lasers are everywhere!!!
Posted at 1:56 am on Dec 9th, 2008 by Grovenstien
threepointone:
How about using an LCD type thing in the beam path to switch it on or off? Basically a standard projector, but with a single moving instead of many stationary pixels.
Posted at 3:07 am on Dec 9th, 2008 by ThatGermanGuy
LCDs switch even slower than a laser diode, so that wouldn’t be a practical way to go.
Check out andycon’s scanner work at http://www.laserpointerforums.com. His stuff’s very accomplished for DIY.
Posted at 3:40 am on Dec 9th, 2008 by thekanester
I think the mirror idea is a better idea than moving the laser itself. Maybe instead of using servos you could use regular motors and just have the horizontal spinning like crazy, then have a stepper motor to precisely control the vertical axis, that might make it so you wouldn’t need week long exposures to make laser pr0n. And green laser pointers are getting cheap enough that he could add one right next to the red laser and then have a little more flexibility.
Posted at 6:17 am on Dec 9th, 2008 by mike
Use voice coils out of two speakers driven by a DAC. Have the voice coils attached to a mirror so one controls ‘x’ and the other controls ‘y’.
Posted at 7:39 am on Dec 9th, 2008 by Frac
@ThatGermanGuy
Yep, do it easier this way:
A spinning mirror for L/R transaltion, another spinning mirror for U/D translation. Put a large LCD (like what are used in digital watches) at the exit point, and simply flash that on/off as needed. The mirrors spinning at a known speed should make it possible to calculate the pulse time and pattern.
You could even get even more complicated… use two sets of the above, and use a sonic (or laser ;) ) ranger to find distance to correct for binocular distortion… and you would have an effectively double scanrate.
Posted at 10:05 am on Dec 9th, 2008 by draeath
LCDs are even slower than your garden variety laser diode. You can modulate cheep laser diodes at 10khz no problem (the expensive ones go into the tens of ghz) which is more than enough for simple work like this.
Also, you can greatly simplify your work by starting with the print head out of a laser printer (although it would be a good idea to swap the diode out for something a little more visible, the ones out of a dvd-r are fast bright and singlemode), which has the rotating mirror and will give you a sync signal to keep everything aligned. Then you only need to rotate a long first surface mirror (that was probably in the laser printer print head, but you could probably find a lighter one in a scanner) to do the y scanning. You could probably get away with using a servo for that axis (as long as it is a fast one), but a piece of polished hexagonal rod on a stepper motor would be a heck of a lot better.
With that you should be able to create a screen that can scan about million pixles/second, maybe 10 million if you are good with analog design. Even a 320×240 screen would be able to have a decent refresh rate.
Best idea on such a budget would be to ditch the servo idea altogether and and mount mirrors on loudspeakers for X and Y.
Solid state lasers can blank plenty fast enough. My DPSS using crappy TTL modulation can do over 40kpps. You are going to hit the limit of the scanners and/or microcontroller long before blanking becomes an issue. I have an arduino driving my scanner right now and the biggest bottleneck lies within timing issues.
Ruby lasers are so early 70’s.
Real men and women actually use argon/ion lasers with PCAOM’s. This is changing as DPSS lasers are becoming increasingly powerful at far lower costs. An entire RGB DPSS setup with over 1 watt output is half the cost of even a crappy PCAOM and can do far more colors, much faster.
The comment on stepper motors reaching a scan limit is true, but nowhere near in the speeds of this application. Symbol handheld barcode scanners use(d) steppers with no issue. Actually there is a guy on ebay who sells salvaged ones exactly for this purpose. Operate them unipolar and use the other windings as a damper and you get very close to what actual galvos are. Granted don’t expect them to be cambridges or anything but on a budget using an audio amp and the most basic of DAC’s you can do some nice beam shows with them.
Posted at 11:53 am on Dec 11th, 2008 by Joe
so, i guess i build this one.
i never ment it to be of use or anything, this is just a 4hours-hack with stuff already laying around.
building a human-visible picture generating laser scanner with servo motors is a bad idea, but i like the two-layer-hack when the image only becomes by using a camera.
it should be more seen as a “movable laser dot”, the picture creation for cameras is just a software thing.
next i plan to hang it in front of a map on the wall and use it to display geocoordinates. cool for quickly finding something, or for automatically displaying geotagged rss stuff like flickr image uploads, traffic, wahtever will come to my mind..
but thanks for commenting! at least i generated a healty discussion on how (not) to build a laser picture scanner.
Posted at 12:10 pm on Dec 11th, 2008 by kap4001
The map idea sounds awesome man. I think it would be cool to try and find a huge sheet of glow-in-the-dark material and post it on a wall, you could then draw and have it stay for a short time.
It would also be cool to pull traffic data and show local congested routes.
Posted at 4:27 pm on Dec 11th, 2008 by joe
nice project. i like the tinyprojector from the comments too.
you can do a slightly faster moving dot with a cd lens and a mirror instead of the servos.
u can see it at http://www.instructables.com/id/Micro-LASER-Show-with-a-CD-Lens-Mechanism/ ;)
to get even basic ntsc quality video, the laser has to scan horizontally at over 15kHz. a very fast spinning motor with a flat mirror and a blanking interval is the only way to go.
Posted at 10:33 am on Feb 20th, 2009 by stevediraddo
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rather lame
Posted at 7:51 pm on Dec 8th, 2008 by burnliff