Intro: Pocket Laser Vortex of DOOOOM
The Pocket Laser Vortex of DOOOOM will project a cone of laser light and give a spooky effect to spice up any Halloween party. A bit of party smoke and it will look like the gateway to Hades has opened. It uses a standard laser pointer and a few simple bits and bobs from around your workshop.
This is an entry in the HALLOWEEN competition
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The idea for this was spawned after seeing Mever's Laser Vortex. My version is rather more compact.
Step 1: Tools and Materials
Building the Laser Vortex of DOOOOM does need some simple soldering so you will need soldering iron, solder and wire cutters. You will also need some way of making a 3/4" (17mm) hole in plastic. The best tool for this is a step or cone drill, but there are dirtier ways of doing this if you haven't got the drill. A round file would be useful here as well. It's all held together with glue from a hot glue gun.
The parts you will need are :-
A small motor - The tray motor from an old CDROM drive is ideal.
A laser pointer - Mine is a 10mW green one.
A small switch - Slide or toggle. Simple on/off single pole will do.
A 9V PP3 battery and battery clip.
A 100 ohm resistor (brown black brown).
A 4" (100mm) piece of 5/8" (16mm) diameter plastic overflow pipe.
A plastic box - Mine is approx 4.5" x 2.5" x 1.25" (110mm x 70mm x 30mm).
A child's powder compact mirror, CD or other mirrored plastic.
A standard laser pointer is a sliding fit down the standard overflow pipe, and as it enters it presses the 'on' button to energize the laser. If you're using a smaller or larger diameter pointer you will have to find a piece of tube of the right size. Check your local hardware shop.
The motor from the CDROM drive is perfect because it is short and fat and has a pulley fitted to give a flat surface at the end. However, any small motor will do as long as it will fit diagonally inside the box.
For the mirror, any small piece of mirrored plastic will do, but some silvered surfaces diffuse the light rather than reflect it. To test, bounce the laser beam off it and onto a piece of card. You should see a well-defined spot and not a series of lines or 'spray' pattern. At a pinch, a manufactured CD will do it but it it should be one with only a small amount of data so you can cut out a bit of unwritten silvered plastic.
Step 2: Wiring Up the Circuit
The circuit is simply battery, switch, resistor, motor, battery. The photo shows how I've connected this, using the spare terminals on the switch to anchor the resistor so it's not dangling in the wiring. (The resistor is shorted out in the 'off' position but the feed from the battery is disconnected so no current flows.) The resistor is there to reduce the current taken, slow the motor down a bit and increase the battery life.
Step 3: Preparing the Motor
The vortex is made by reflecting the laser beam off a spinning mirror, angled slightly away from flat. This projects the beam in a circle as the mirror rotates.
The best motor is from an old CDROM drive. Usually it's 4 screws and a bit of wiggling to get the covers off, and the tray motor is the one near the front of the drive with the drive belt on. A couple of screws to undo and a bit of desoldering and it's out!
Cut a circle of the mirrored plastic around 3/8" (1cm) diameter. It doesn't have to be perfect, but trim it to an approximate shape. I used a pair of wire-cutters to do this, but be careful not to distort the plastic.
Put a blob of hot glue on the end of the motor pulley and centre the mirror on it at a slight angle to flat. Look at the picture to see how much to angle it. Hold it in place until the glue is set.
Hold the motor and turn it on. If you're lucky the motor will spin without too much vibration. If it does vibrate, trim one of the edges and spin it up again to see if it runs smoothly. Once it's reasonably smooth, check the alignment as below.
Shine the laser at the mirror with the running motor held at 45 degrees to the laser pointer. The beam will reflect off the mirror and form a circle. Project the circle onto a flat surface and it should be around 1' (30cm) diameter at a distance of 2' (60cm),
If it is near this, all well and good. If not, carefully lever off the mirror and do it all over again. Once you have the angle right, try and reduce the vibration more by trimming the edges again.
Keep going until you're happy with the angle and the level of vibration. It took me two mirrors and half a dozen re-glueings to get mine right.
Step 4: Drilling the Box
Drill a small pilot hole in one of the short sides of the box, 1" (25mm) from one edge. This is the hole that the plastic tube will go through, so if you haven't got a large enough drill, make it as large as you can.
Ideally you'd use a step drill - My set will drill a neat hole from 4mm to 30mm in 2mm steps.
Because not everybody has one of these, I enlarged the hole using a brute-force method by twisting my wire cutters into the hole. Some may cry 'tool abuse!' but as it's reasonably soft plastic, the cutters didn't suffer in the least. Any solid, sharp edged tool with a sloping profile would do the job. I tidied up things with a round file so the plastic tube was a good fit through the hole. It will be glued in place later.
Place the tube and the motor into the box and work out the position of the side hole where the Vortex will emerge. The motor should be at 45 degrees to the axis of the tube to reflect the beam out. Make a second hole here, as large as you safely can without weakening the top of the box side.
Drill and file a smaller third hole on the short side with the tube entry to pass the slider of the switch through.
Step 5: Putting It All Together
Look at the first picture to see how it all goes together. Mount the switch and install the battery using a double sided sticky pad. Hot glue the tube in so it's parallel to the base and sides of the box, and half an inch short of where the mirror will be.
*** IF YOU ARE USING A HIGH POWER LASER TAKE FULL PRECAUTIONS FOR THE NEXT STEP ***
Temporarily tape a piece of white paper on the outside of the box over the hole. This will help you centre the emerging laser cone in the exit hole. Insert the laser and switch the motor on. Place the motor in the box in a position where the laser beam hits the centre of the mirror and it projects a circle centrally on the white paper.
Remove the motor and put a good dollop of hot glue at this position. Then replace the motor, re-establish the circle and hold until the glue sets. Take off the paper, screw on the box lid and admire your Pocket Laser Vortex of DOOOOM.
Step 6: Let the Gates of Hell Be Opened!
To get the best results from the Laser Vortex of DOOOOM you need some party smoke. This is an aerosol which sprays a very very fine mist of vegetable oil into the air. A proper stage smoke generator or CO2 mist generator would probably work even better but I haven't been able to try it with one. You can buy the aerosol from most party shops, and from Maplin (in the UK).
You should set up the effect in a room where there isn't much air-flow to maximize the time the smoke hangs around. You can either position it with the cone vertically or place it horizontally so that people have to walk into the Vortex. Because the beam is scanning and only spending a tiny fraction of a second on any one position a normal power laser pointer won't cause eye damage (extrapolated from FDA guidelines). If you are using a high power laser, take all the normal precautions to stop people looking into the beam.
The videos don't really do the Vortex justice - The real-life effect is much better.
I'll try again this w/e but need to get more smoke first.
Sanity warning :-