I’ll be honest – I didn’t take anywhere near enough pictures of this. After the first hour I quickly descended into a geek trance and emerged a few hours later, slightly disheveled and holding a working working laser show but possessing only 13 pictures, many of which were terrible and irrelevant. So I apologize, and I’ve tried to make everything as clear as possible in the instructions themselves.

Power Supply and Control

The first thing we want to do is provide power to the laser itself, and provide any easy method to turn it on and off. The power is coming from the AC/DC adapter, but it ends in one of those plugs we’re all so familiar with. What we need to do is wire a receptacle (which connects to our power adapter plug), to a switch (which allows us to turn power on and off), which then goes to the laser driver board itself.

Cut out appropriate holes for the receptacle (generally a circle) and the switch (generally a rectangle). For the receptacle hole, I used an old soldering iron that I speared into the plastic – feel free to say “THIS… IS… SPARTA!!!” while doing so. For the hole for the switch, I used a Dremel tool and cleaned up the edges with the old soldering iron.

Solder up the receptacle, the switch, and two leads that you will eventually connect to the laser driver board. Use electrical tape to cover up any exposed contacts. It’s up to you to make sure you wire the switch correctly – there’s a ton of different ones out there, make sure to read the specifications. Don’t worry if it doesn’t work, there’s really only one other way to wire it.

Don’t connect anything to the laser yet! Why? We need to mount the switch and the receptacle in the box, and you’ll quickly find that you need to pass the wires through the little hole in order to mount the switch. The laser, needless to say, will have a bit of trouble fitting. Put everything into place, and apply glue to the inside to ensure everything stays put. You don’t need to do this, but it doesn’t really hurt.

Now put on your laser safety goggles. You can take them off if you leave the room to go to the bathroom or something, but trust me, when you look this good, you’re gonna want to leave them on.

Now we can solder those leads to the laser. Be careful that you don’t use excess solder and connect the two power pins to each other! This can always be fixed, but it’s easier to do it right the first time around.

Now fix the laser driver board to a part of the box. I picked the side and set it vertically to leave the most available space, and used a glue gun to mount it since there weren’t any easy screw mounting points. If you look at the board there should be a big piece of metal attached to a component, that’s the heatsink for the power transistor. Make sure it has lots of free space around it, it can get hot and needs to cool off. You can see how I chose to mount everything in the picture at the end of this article.

Don’t worry about mounting the laser itself yet. Make sure the laser is pointing away from you at something non-reflective and cheap (a piece of wood is great), plug the AC/DC adapter in, and turn the switch on. You should see a whitish dot appear. You only see a dot instead of bright green glare because you’re wearing your safety goggles. You are wearing your safety goggles, right?

Alright, now we have a working laser that we can easily turn on and off! Now turn off the switch and remove the power adapter (do both!).

Laser Modulation (or, a little mirror that moves)

Now we need to grab those headphones and take them apart. It’s a lot less complicated than you think. Each set of headphones will be different, just keep taking out screws and gently cutting away plastic until you’re left with the speaker and cord from one side. There should be two wires (or possibly the two wires are covered in plastic so they look like one wire) leading from the cord side into the headband thing. Cut this wire, and use electrical tape to nicely cover the exposed ends of each. I don’t think connecting them is a good idea (drain too much power?), but like I said, electrical engineering is not my specialty. Feel free to comment.

Now you should have one speaker attached to a cord that you can plug into an iPod or a stereo. Plug it in and start playing music to make sure it all works. Now look at the speaker as music is playing – if you’re lucky, it’s nice and exposed, and you can see the speaker cone moving back and forth. If you aren’t, it’s covered in a plastic mesh or similar. Cut it away carefully (I used an old soldering iron again, being very careful not to hit the speaker itself) so you can see the speaker. We want to be able to glue the little circular mirror on the speaker itself.

Grab your glue gun, dab a bit of glue on the back of the mirror, and quickly and carefully place it right in the middle of the speaker, ensuring it remains flat. Don’t get any glue on the mirror itself, and use a tissue to wipe off any fingerprints (or, if you wear glasses, use your cleaning cloth).

Alignment

Now we want to place the headphone/mirror inside our project box, and align the laser correctly so it bounces off the mirror. I found it easiest to first place the speaker at a 45 degree angle, and fix it in place at one of the box with the glue gun. I also cut a small semicircular notch in the side of the box to give the headphone cable an easy mounting and attachment point in the box.

Ensuring the laser remained parallel to the bottom of the box, I then I adjusted the height of the laser with a mounting made of popsicle sticks. The end result is a beam which bounces off the mirror at a 45 degree angle and then heads straight for the ceiling. This is the easiest way to mount the laser so you don’t need to worry about it hitting your eyes on a regular basis.

Mounting the Diffraction Grating

Now we need to place the diffraction grating so that it intercepts the laser being reflected off the speaker, and breaks it up into hundreds of different beams. We want to place the diffraction grating directly above the mirror if you’ve aligned your laser with a 45 degree reflection angle.

Use a Dremel tool or similar to cut a hole in the top of the project box that’s slightly smaller than the diffraction grating. Then mount the diffraction grating in place with the glue gun.

Final Testing and Assembly

You should now have something that looks somewhat like this.

Don’t worry about that tan circuit board with the LEDs attached the to the diffraction grating, they’re some lights that came with the specific type of headphones I used. I kept them in because they looked kind of cool, not for any technical reason. You don’t need them. Check to make sure that the laser turns on, and that it bounces off the mirror correctly at rest and when music is playing. Then box it all up, and you’re ready to go!

You can see that I’ve added in some ventilation holes above the laser and main power transistor. Do this! The laser will produce heat as part of it’s operation – it’s not normally a big deal, but a sealed box has a way of drastically increasing temperatures.

I hope this helped you – and if you have any questions, just post in comments!

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36 thoughts on “The Ultimate Home Laser Show – Assembly

  1. Very nice! I would love to do something like this, but do you have any more information on the laser power/make/model/availability of the driver?

  2. I’m of the “bigger is better” school of thought. If I had say a large cheap regular speaker laying around , could I use that? Does it have to be a fairly small speaker?

  3. Phoghat – Should work great!

    The bigger the speaker, the bigger the patterns. I used headphones because they were the largest speakers I could find that were cheap and could be run from a laptop’s sound output.

    Obviously you can’t run a large speaker off the same signal you’d use to drive headphones. If you have amplified the signal sufficiently, a large speaker should look amazing.

  4. I was looking up diffraction gratings, and I read that a CD can act as a diffraction grating. Would you just strip the aluminum, lacquer, and labels from the top to leave a clear disc?

  5. Kikaruu – In that case, the CD itself acts as a reflective diffraction grating. The laser light hits the aluminum, and since it’s divided up into all those little grooves, each groove scatters light differently and you get those interference patterns resulting. As such, you’d need to use the entire CD – the plastic cover protects the aluminum, which reflects and diffracts the laser light.

    edit: I’m not entirely correct – you can use a CDR stripped of it’s label to create a transmission grating. See the comment by Maruti from January 8, 2009.

  6. I want to build it but you didnt include the pair of headphones you recommend using. I don’t know which speakers to use, please explain more into the audio bit of your guide as I get everything else except the audio section on wiring the headphones, I dont quite get…

  7. Hey Daniel –

    I couldn’t find a link to the headphones since they were discontinued and I got them on sale. What you’re looking for is the big “over ear” style of headphones. The larger the speaker, the more it moves – and the animation of your laser will be correspondingly larger.

    Then, you remove all the plastic from them so you have an audio jack leading to two bare speakers. You only need one of the speakers, so remove the other. Then you mount a mirror to the speaker itself. When sound is played through the headphones, the speaker will move, and the mirror will vibrate.

    Then you mount everything in your project box so that the laser bounces off the mirror attached to the speaker, and then goes through the diffraction grating.

    Does this help?

  8. Hi, that helped since you dont have the link to radioshack because its discontinued do you have the model or style number for I can maybe purchase it somewhere else.

  9. Sorry Daniel, I don’t have the model number. Honestly, it really doesn’t matter what headphones you use at all as long as they can 1. accept audio input from a source of your choice, and 2. vibrate sufficiently at typical volume levels to move the laser to the degree you want.

    You could also purchase a raw speaker and wire up an audio jack to it – I just used headphones because they were cheap and readily available.

    • Hi Conor,

      It has roughly a 90 degree spread – the laser show will be around two feet wide for every foot of vertical distance between it and the ceiling.

      I’ll sit mine on a coffee table (roughly 6 feet to the ceiling) and it produces a show about 12 feet wide. Faint dots are visible outside of this but I don’t really count them. Note that this depends on the diffraction grating you use – some will spread more, some less.

  10. Im looking to build some stuff to use as a light show for a band, i think this would be cool if i could do it. I’m looking into the laser situation now, but how dangerous to eyes are we talking? I wouldnt be able to hand out safety goggles to everyone in the audience. If these are very dangerous, how o bands such as Pink Floyd get there lasers going safely?

    • Mat –

      From a realistic sense, very little real danger. From a litigation standpoint, it’s a different story.

      Audience scanning is largely banned in the US, but allowed outside (ie relatively common in Europe). The type of laser shows Pink Floyd used to do would likely no longer be allowed in the USA.

      Personally, I view the risk of the laser show to the viewer as minimal as long as it is pointed toward a wall or ceiling and not directly at the viewer. I recommend safety glasses for the construction, as there is significantly more risk in this activity.

  11. Hi Geoff, thanks for this great project but i read something about IR radiation : ” no IR filter between the crystal and the lens – the invisible infrared light is dangerous for your eyes ” from a guy on Deals Extreme about this laser

    Is the radiation only dangerous when directed only in the eye ?
    thanks for your answer.

    • Hi Matthieu –

      Yes, IR can be a risk especially for laser projects involving green lasers. The major issue is that IR is invisible, so it is possible for eye damage to occur without it being immediately obvious.

      Care must be taken in construction. My personal take is that I believe the level of radiation (IR, visible, or otherwise) once split through the diffraction grating to be reasonable in terms of an average person watching the show. Anything else I would be reluctant to reccommend.

      I’m not particularly attached to the DealExtreme laser itself – if you can find a lab laser with an IR filter in a similar power range (10-30 mW or so) go with it (Aixiz can be good). I just wanted to link to the one I used in case people are curious, but certainly many other models are possible.

    • Hi Maruti –

      To remove the label (source http://www.arborsci.com/CoolStuff/cool22.htm):

      “If clear CD-Rs with data tracks are not available, you will have to remove the laminated label from an ordinary CD-R. To do this, position the disc with the label side up. Using packing tape or duck tape and a quick pull of one or two pieces of the wide tape placed across the label will result in quick removal of the label.”

      This grating will likely not produce nearly as many “points” of light as a commercial grating, but should certainly work. Let me know how it goes!

  12. I’m a little confused by the audio portion of this. If you have the audio jack from the speaker/headphones plugged into an Ipod, wouldn’t you need another Ipod simultaneously playing on another sounds system to get the laser show to sync with the music?

  13. Hey, I tried hot-glueing a small mirror to a pc speaker I had laying around. I don’t have the diffraction grating yet but I figured the speaker would bounce my single laser dot around. Sadly the only movement I can see is from my own shaking trying to hold it steady. The speaker is clearly moving and mirror is vibrating when I touch it. Does the diffraction grating make all the difference on this project? Thanks!

    • There are two possible issues here I think:

      1. Your mirror isn’t actually moving. It may feel like it’s vibrating when you touch it, but that vibration may not be enough to actually drive the attached mirror to any real degree. This is a risk if your speaker is very small/underpowered.

      2. Your distances are not sufficient – the patterns this creates are not large, and require a bit of distance to spread themselves out to a nice size. Rough rule of thumb to make sure it’s visible would be 6 inches from the laser to the speaker, and 6 feet from the speaker to the wall. If you don’t see it then, something’s wrong.

      Best way to check this is to set up a mount so your laser is steady, and arrange it so there is sufficient distance to the wall. If you see a pattern, the distance was the problem and your shaky hand was overshadowing it. If you don’t see a pattern, then your speaker is not powerful enough – try turning up the volume or using a more powerful speaker.

  14. Ok i just dont see headphones making this even remotely loud. Can i use all of the same parts and wire a speaker up to it. If then What would i need to do. Please help

  15. I was wondering about the safety glasses, what kind did use and where is the best place to buy them. Just looking around it seems like they will be more expensive than all the other materials.

  16. Hey Geoff,

    I cant seem to find a good matrix diffraction grating anywhere. And on the website you linked to buy it its sold out. I was wondering if you had any ideas where to get the grating from.

    -Thanks, Adam

    • Hey Adam,

      You’re right, I found sourcing the diffraction gratings to be very difficult as well. If Dragon Lasers is currently sold out, perhaps try here:

      http://www.rainbowsymphonystore.com/difgratfilsh.html

      They only ship to the USA (so I haven’t tried them), but others I know have. The “matrix” style would be “01503 – 13,500 lines per inch – Double Axis 8″ x 10″”

      It’s a plastic sheet rather than a glass square – so less durable but you get more of it and it can be cut with household tools.

  17. Hello sir geoff!

    I have bougt the laser and have put it on an old handy cabel whit output 4,9 V/450mA(blue and red cable). but the laser doesn’t work! only the red led on the platinum is on! Can you please tell me what i make wrong?

    Thx Patrick

    • Hi Patrick –

      Few things:
      – I’ve heard that some lasers were shipped out with circuit boards that take 5V AC rather than 5V DC. Seems a bit odd to me, but something to check out.
      – My laser died after a few months of somewhat heavy use – I have a feeling these are not the highest quality lasers out there. It is possible that your power regulation circuit is fine (ie red led on) but the module itself has malfunctioned. You can contact the manufacturer for a replacement.

  18. So would you be blinded from looking into the light being directed from the box?also do you think a disco ball would get it to cover the entire room?

  19. u had make a great thing and for this i am very thankfully to u . but i want to ask a question that where to place the mirror can u please see it in picture and why u r using the specific laser light not a normal one ?

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