Norm's Homemade Laser Show

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History:

 

May 14, 2006 It's been a while, but here they are: my projection results for Version 6. Also on the page's bottom, I added a few thoughts about why I am getting this so-so performance, and potential solutions to it. I added another new page on how I made the coils. Yes it's a double update! Lately, I have been working of the schematics on Eagle. I'm learning how to do PCB routing - very exciting. The more I learn about this program, the more I like it. BTW, you can get your free copy on Cadsoft's web site.
April 20, 2006 SW update : see releasenotes.txt in zipped files fro details. Many changes. See Download section at bottom of page.
April 2, 2006 A little update for the SW. This includes code for InstantText, as some of you have requested to see that. Go to the download section. In the program, select Create / Text to display, then type your text and choose a delay. Phrases will be cut into pieces, every time a carriage return is found (when you press enter)/ So your entire text will show as a sequence of phrases of 13 characters max. Also, the InpOut32.dll file is included in both zip files. It needs to be located at same folder as the Lasershow.exe. Text entered to display will be saved to Lasertext.txt file, and an .ini file is now generated to store program settings, instead of using registry. About the HW, I didn't have much time to work on it lately because I am building another pro box for a new client, and this is very much time-consuming. But I can't wait to see my homemades perform! Just be patient...
March 23, 2006 Here's my 800 microsecond record! This is very close to Chan's achievements. I still can't do 500us, but at least I have something stable.
March 5, 2006 Major SW update. Now infinitely faster to load ILD files. Added more configurable parameters, such as LPT port base address, and mouse/pen scan rate for scribbling. Fixed many bugs and annoyances for drawing. Now works great, especially when using a digitizing tablet and pen. Added auto-interpolation to prevent large galvo jumps when drawing. Added and automatic speed adjuster - very convenient. Don't have to bother anymore on setting the scan speed depending on every ILD file. Even adjusts itself while scribbling - cool!. Added "Update while playing" in case you want to see screen updates in sync with laser output (but slow of course). Fixed an old intermittent crashing problem, by adding protection for cross-thread accessed data.
February 26, 2006 Tried to tune the version 6 galvo again, with shielded cabling and without feedforward like Chan. See result here. Added pics of my box, as sold to the client.
February 25, 2006 Added pics of the open-loop speaker based laser show, as many people have asked me to do so.
January 31, 2006 Updated my software to be able to configure which DAC circuit is used. Either my own or the famous and simple DAC0832 circuit found here: DAC0832. The setting is persistent, i.e. will be saved when you exit program. Updated source code also. Other good news : I finally received m y green DPSS laser replacement from eBay's seller aixiz_lasers. I strongly recommend this guy's products. He has the best prices, sells good quality items, backed up with a solid warranty.
January 12, 2006 Received all the parts to build my first attempt of a serious optical PD, based on pro galvos. I can say it's a success. Go see for yourself - simplicity itself.
December 18, 2005 I'm back to HW design again! After seeing our new friend Satrek's successful implementation of the famous optical PD, I decided to go ahead again with that myself. First thing was to find and order some of those large area phototodiodes. I found what I needed here : http://www.fairchildsemi.com/pf/QS/QSB34.html and ordered 20 of them. This, with a totally new approach on the galvo construction, and again inspired (or even copied) from Satrek, I started to build Galvo Version 6.
November 28, 2005 Added lots of new code to my SW. Like the possibility to create, copy, paste new frames. But mostly, to optimize frames that have been imported by the Import Illustrator files feature. This puts back the paths created randomly by Photoshop in such a way that the galvo has the least retraces possible. Also I added additional anchor points and velocity points to nail down the paths and ease retraces. I also got rid of the message on Win2K/XP that told you to install UserPort. None of that now. It will let you run, but the GO button will be disabled. So this way you'll be able to use the tool to create animations off line. Go check it out.
November 23, 2005 Fixed many bugs in my SW, and added a cool new feature : Import Adobe Illustrator file (.AI). This enables using paths created from a bitmap image in Photoshop, to create complex shapes almost instantly. First, you have to load an image in Photoshop, do a selection based on color, then convert the selection to a working path, then export to .AI. In my SW, you import that .AI and it will merge into the current frame. You can also draw the paths directly in Photoshop, i.e. without first loading in image. You will see a few .AI samples I created. After you have imported them, you can play with the "Minimum point distance" value to allow more or less points for the paths. Now, the problem is that I will have to allow modifying the point and path order, because Photoshop, of course, does not try to minimize useless and huge galvo steps.
November 13, 2005 Finally posted those highly awaited pictures and movies of my new Pro Galvos Kit. In resume, I can say I am very impressed by the quality of the product and would certainly recommend it to people who want a quick OEM laser show without going through the adventure of developing galvos as we do it in these pages.
October 27, 2005 Received my new 100mW laser !!! That little beast is so bright, unbelievable. Did more videos of my real-time math functions - nice. Also, did some modifications to my galvos and drivers. See here for details. I updated my software again, added many math functions and a random sequencer.
October 26, 2005 Had fun tonight, making more movies and taking more pictures, with a slower shutter speed on the camera.
October 25, 2005 Improved the software a bit : bug fixes, added possibility to freeze frame, invert the axis, or swap them on the fly. Still need to add the documentation, as more and more people seem to be interested in using this SW - cool ! Also, I added the utility called "UserPort" (thanks to Tomas Franzon), which enables my SW to access the parallel port directly under Win2K/XP. This is not required under Win9X/ME. Read the instructions in the PDF on how to use it. Basically, leave the left column empty, and in the right one add 378 (typically - may vary depending on your PC), then press Start. At this point, my SW can be started and will output points.
October 19, 2005 Added my changed components' values to the discussion group, so you can compare with what you've got. You'll see that they vary a lot from Chan's design. I suspect that this is due to the magnet's parameters of mass and maybe field strength. Since we're all pretty much using the CYL075 magnet, I hope to see your values close to mine, as it would enforce my theory. Also, a big surprise... our dear friend Jose has finally sent us his video of a very successful laser projector. This lucky guy is doing his master thesis using this project, if I'm not mistaken. Imagine how much fun it must be to do this all day long! Congrats Jose, you deserve my honors and respect !
October 3, 2005 Put all the breadboard circuit to PCB, and did some tests. Results are not bad, but not as good as I expected. The ripple is not gone, but diminished only. The speed is absolutely the same. The precision and stability are lacking just as before. In fact I get almost the same results as the breadboarded version. I think my X axis disc has a broken or loose conductive paint joint that causes the instabilities. The only major improvement is the magnet damping. The conductive grease also helped a bit. There are lots of new pics and many movies too. Also, lately, a guy named Bill Lu from China found this web site and decided to send me an email. Read more about it here.
September 14, 2005 Summertime is over ! Had a great one, enjoyed lots of sun, water, camping, motocross, women, etc., but also some overtime at work to spoil all that fun. Now, back to business. Let's make this project a success. First, I compiled a few new and old links that I thought were good and appropriate miscellaneous section. Also a few new friends in the links section. Other than that, I added conductive grease to the shaft where the ground wire was rubbing to make better contact. This improved a bit, but still shaky sometimes. Added a few routines to my code to make cool real-time math and random patterns. Not updated code download yet though. I can see some of you guys are reaching me and this is really exciting. Thanks for visiting regularly. I already reached the 10000th hit lately - COOL!
June 19, 2005 Did some major improvements on both the circuit and software. See by yourself the pictures and movies I've taken. Updated the download section with new code and executable.
June 13, 2005 Finally some graphics to show! But it performs extremely poorly. I took a few pics to show you what are the results of my last 6 months of intensive research and labor. As you'll see, it's worth asking myself: "Should I continue with this project at all..." After all the time and money invested, I could have bought a set of high quality galvos at 30kpps with drivers and even the laser. Man I'm so depressed. I'm not even close to my goal, although I took all the precautions in the world to build this carefully, using only the best parts available. What the hell is wrong with this project ?
June 8, 2005 No pics today, but lots accomplished though. Completed the second galvo's hardware. Rebuilt the PD from scratch using the same method as for the other one since it worked so well. There's no more electronics on top of both. All is on breadboard. Maybe will be able to use only one oscillator with separate buffers instead (will explain later). A few tests and a quick look at the scope tells me that both galvos seem to react the same way, which is good sign. The plan now will be to finish the driver for second channel and create a mounting platform for the assembly and the laser.
June 6, 2005 Worked on second channel galvo called Version 5E, and mostly on the PD stator plate design, to make it less noisy by applying Chan's recommendations about shielding. I did review the oscillator circuit and improved the filtering also because I had lots of residual 10MHz in the PD signal. These two made a very noticeable difference. I made captures to show you. Added more friend's pics too. Worked a bit on SW, but no update yet.
June 3, 2005 Made lots of progress on the software again tonight. Can now save ILD files. Ctrl-Del to delete selected point. Added navigation keys: Ctrl-Up/Dn/PgUp/PgDn/Home/End. For the curious, the code can be found here. It's a Visual Studio 6.0 C++ project, using MFC.
June 2, 2005 Worked on the software these last days. You can check what I did so far : can load ILD files, browse through the frames and points (try with up/dn arrows when focus is on Current frame field), add/modify points and create new file. Save will be implemented soon. Will come back to give details later...
May 25, 2005 Answered that frequent request : where to find a source of good and cheap mirrors? My list of friends gets bigger everyday. I forgot someone and that's unforgivable: Sam's Laser FAQ. Created that famous Friends' Galvos Pictures page.
May 24, 2005 Major weekend! Did many things, like using quality shielded cables all the way to improve stability (changes everything!). Traded the LM675T power opamp for the OPA541AP and put it on a separate breadboard to prevent influence on low power circuits. Did many tests with storage scope. Here are the results.
May 19, 2005 Thanks for your contributions to the discussion group. It's already very interesting. This week end, I did the ultimate speed tests, to answer that question once and for all : how fast can this galvo be? Added many pics of my other interests, just for fun.
May 9, 2005 Added a discussion group. You are invited to post messages here, so we can all benefit from each other's experiences and stimulate creativity.
Yesterday, besides visiting my beloved mother, I discovered that my PD disc and stator plate were a bit too near to the galvo's heat sinks. This seemed to be the main cause of the distortion I had and various instability problems with the PD as soon as I began pumping a bit of juice in the coils. I just added two little spacers to move them farther from the metal, and more "floating" away from what I think may have been some radiating energy from the coils. The effect was dramatic. Currently, I can inject a square wave of 160 Hz at the input of the driver, and I can see an almost triangular with full amplitude at PD's output. I have no idea if this is good or not. To me, it appears quite crappy ! I decided to hook up the DAC board I used with my old open loop system, to see how the galvo would behave with more complex wave forms. I was surprised to see that it can follow the original signal with "some" fidelity. So I was happy to see that it worked, but deceived by speed and accuracy. See the added pics for version 5C. Updated my crystal oscillator circuit, because it stopped working when I put it on PCB. Added lots of new info in miscellaneous page.
May 05, 2005 No panic, I'm not dead! Many of you have asked me what was going on these days. I seemed to have neglected my pals a bit. There are about 30 of you guys with whom I chat on a daily basis (though thank god, not every day), and I am starting to loose control of my emails, i.e. what did I answer, to whom and when, and did I sent that email or not? Or was it from home or work, etc. Doing this for me is very much fun, but it's also becoming very time-consuming. So I will have to ask you a very little and simple favor : from now on, send me emails only at my home address : legato@videotron.ca. This way, I will have everything at one place, and won't have to forward everything back and forth. I will create a rule to automatically forward any email to work, containing the word "galvo", so during break time or lunch, I will enjoy reading you. BTW, I'm really sorry if sometimes I miss replying or take too long. Just send again!
So...what's up? Well, many things. First of all, my scope problems are gone. I just went on eBay and bought another one, same model and will keep the broken one for spare parts. Then I spent the last weekend with my cousin Simon from Montreal (thank to him BTW). He's a math wiz, and he is really fascinated by my project. We tried together to understand the driver circuit from bottom up and even redid the PID circuit from scratch. Having problems with the grounding of the shaft, and PD reliability, I decided to try something different: optical feedback. At the end of the weekend, I found what might have been a big source of problems for me since the beginning - power supply. Check the bottom of the links page, there are new entries.
Apr 26, 2005 Emotional were the last days... My scope died suddenly, and for no reason at all. I turned it on and it jammed in its self-test sequence. Diagnostic code: main board failure. Grrrrr!!!! But that did not stop me!!! I received my new diodes for the PD: NTE594: very good performance. Finished assembling galvo version 5C and did PD tests by hand. Found a way to provide good ground on shaft, but wonder if it will last.
Apr 18, 2005 Added more pics in version 5B. Gives a better idea what this big guy will look like. Talking of big guy, I decided to add a more personal touch to my site. Here are a few pics of me, Norm the "mad scientist" in his lab. Also, a tour of my lab setup, just for fun. Unfortunately, I will be gone on a field trip, and there will be no update until next week.
Apr 15, 2005 My server is up and running again, thanks to a backup image file of my OS that I made a few weeks ago.
Apr 11, 2005 Found something interesting, by pure luck: Use Pentium heat sinks as a base for building galvo version 5. This seems very promising.
Apr 5, 2005 My laser is back !!! Check out Laser version 2. Designed a cool power supply with crowbar protection, current limiting, and analog modulation. Put all this in a neat box with a telescope collimator. Thanks for visiting my site!!! BTW, I haven't received a single email in days... I really like to hear about your progress. I guess we are just all very busy. That's ok. Also, if you have a web site, can you please add a link to me? But do not use the redirected link with the IP address since it may change once in a while. Only this one: http://pages.videotron.com/legato/LaserShow/LaserShow.htm
Mar 28, 2005 Added pics of prototype version 4. This one can really achieve 0.5ms per 8 degree step. Has closer coils, with thermally conductive epoxy, which make all the difference for dissipation.
Mar 25, 2005 Added navigation table at end of pages, because my site is becoming too big. Split into smaller pages so users can print only what is needed.
Mar 21, 2005 Galvo prototype version 3, based on the new magnet. How to assemble your own DPSS green laser. How to blow up your super cool brand new laser.
Mar 16, 2005 Received my magnets from Engineering Concepts. Those CYL0275 are very strong! Received my laser diode to build my new DPSS green laser. Gave it a quick try, and it works. I could see the green laser output, but need to build a stable assembly.
Mar 4, 2005 Added a picture of a technique I have developed to create the coils easily. Added a cheap but efficient oscillator diagram based on the 4049 inverter. Added a few links to friends that have either shown interest in this project, or have something to offer, related to it. 
Feb 27, 2005 Added measurements I took with the version 1 of my prototype. Also added details about making the position detector.
Feb 23, 2005 Back from vacation! Added a little intro and provided redirection to my own web server (need more space and speed!). Added tips on building the two electrodes for the position detector. Thanks for the many mails you sent me. I don't feel alone anymore in this adventure. Thanks also for those who created a web page so we can share ideas, knowledge, tricks and tears : ).
Feb 13, 2005 Added comments, and a PDF document explaining how to interface a 12bits DAC to a PC's parallel port.
Feb 11, 2005 Added more pics of my older speaker based system. Added pics of galvo version 2: an attempt to make my galvo faster with smaller magnets and closer coils. Also an example on how to split a hard disk magnet from its metal holder.
Feb 9, 2005 Creation date, pics of galvo version 1 and comments on the project I'm trying to build : closed loop galvos.
 




Hi laser hobbyists,

This  is a site dedicated to the art, science, and hobby of "trying" to build an home made laser light show.  I've been playing around for many years now with electro-mechanical means of moving mirrors, but nothing is quite fast and precise enough for writing or displaying intelligible animations.  So far, I was able at best to perform random scribbling, Lissajous patterns, simple geometrical shapes such as stars, squares or even alphabet characters, but barely.  Why?  Because I always used opened loop systems, i.e. without any form of feedback.  The system does know where to aim the beam, but has no way to find out how close it is to that goal.  We rely solely on the precision and linearity of the transducer, which is either a motor, speaker or low-end opened loop galvanometer.  But now, welcome to the wonderful world of closed loop systems, where it is possible to tell not only how near we are from our goal, but also how fast we are getting there.  This enables us to accelerate at full speed, then anticipate when to start "braking" and how hard, in order to stop right on the spot, and not exceed our goal (overshoot).  In short, this system is much faster and precise, but also much more complicated.

This site will contain many pictures I took to share with you, along with comments on problems I've encountered, trials I've made, or tricks I've discovered to build some of the components.It shows my work in progress in building a closed loop galvanometer, for eventually producing a full fledged laser light show.

It is based on the great and very impressive work of Mr. Chan, found on this site :

http://elm-chan.org/works/vlp/report_e.html

When I first looked at this site, I couldn't believe it.  How come I didn't think of  this before ?  Of course !  You just have to send an RF signal to the differential capacitive bridge, filter it and amplify the resulting, feed it along with a command voltage in a subtracting opamp to get an error signal, then add some damping and a power output stage, ... and there you go.  Yeah right !!!  Sooo simple...

All this seemed quite simple when I understood the principle, but when I finished building the prototype and the electronics on a breadboard, nothing went as was supposed, and I was very deceived.  This site is all about my misadventures in tuning this circuit and hopefully, one day, make it a success.  I am not a novice, and believe me, I realize now that this project is not for beginners.

I'll keep this site updated once in a while.If you want to talk about it, I would be glad to exchange any tips.

My email:legato@videotron.ca

Bye,
Norm

 


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