Laser Collimator

(Click for larger image)

There are lots of references on the internet for laser collimators. Here's my two cents worth on an EASY, CHEAP and incredibly useful project. I take no credit for this design either!

Pretty simple instructions:

Buy some 2" PVC pipe (assuming you're building a collimator for a 2" focuser) and a pipe cap (for aesthetics) and a laserpointer (I got one of those shorty key chain jobs with 50 different screw-on pattern thingies off of Ebay for $5.). You'll also need a drill and taps come in very handy. I got mine from Harbor Freight cheap...but the quality is equally cheap, so caveat emptor.

Cut the PVC to length and give yourself extra length for a good fit in your draw tube. My draw tube is 4" long and my collimator is 7". Also cut two additional pieces about 3/4" wide. Cut a gap out of the small pieces (>1" on mine) with a hacksaw.

Pinch the two smaller pieces and jam them down into the business end of the 7" PVC section. You want to position these two pieces such that the set screws that grab the laser pass through them (i.e. two PVC body wall thicknesses will improve the ability to center the laser later on. It just gives the screws more to bite into.

Locate the traditional 3 points around the outside of the PVC (i.e. 120 degrees apart) and spot them. Then drill them and tap them to fit your screws. I didn't have enough of the right size machine screws handy (and I was in a hurry) so I used 1" wood screws. The pitch is a bit steep (and they're not the prettiest), but they work fine. (Note: my collimator started shorting out because the wood screws penetrated the paint on the laser pointer and started grounding it out! You might want to avoid this and use nylon machine screws or something to protect your laser. I wrapped mine in a layer of thin rubber.) You also want to drill and tap one additional screw right on top of where ever your laser's momentary on/off switch will be in the finished product. A nylon thumbscrew works real well in this hole. My button fell right smack in between the other two sets of screws. Go ahead and start the screws into the holes. Adjust rotate and position the laser pointer so that you will be able to turn it on using the thumbscrew after inserting the unit into the PVC tube.

IMPORTANT! Find one of the attachments that creates a nice round three-dimensional pattern and put it on the laser pointer before you mount it in the tube. My favorite is a soccerball. I built one for my brother that uses a smiley face :) and it works pretty well, too.

Position the laser pointer in the center of the tube and gently tighten up the machine screws. The next part was time consuming, but not difficult. It's hard to "take a picture" of this, so I'll just try to explain it. What you want to do is find a groove somewhere around your house where you can place the collimator and spin it in the groove. (Meaning you want to put the end of the collimator that goes into the draw tube into a groove and rotate it.) The groove can be as simple as a ledge on the fireplace or the fence on your tablesaw. Basically anything that has two square edges and gives you freedom to rotate the tube will work. Also note that your groove has to point to a flat surface at least 10 feet away. I think farther is better to an extent; in theory, the farther the image, the more accurate the collimator. I cast my image across the garage from the table saw (probably 20 feet). Now that your collimator is powered on and pointed at the wall, all you have to do is adjust the six set screws and rotate the tube until the beam on the wall (the dot) no longer circumscribes a circle. All of the 3D images on my attachments have a center dot in the pattern, so it should work with any attachment you choose. You'll probably find, as I have, that the mechanical axis of the pointer does NOT correspond to the laser pointer's optical axis. A little trial and error will get you to an awesome piece of equipment for collimating. I will never go back!

Here's an image of the finished product using a smiley face attachment.

I will add more info later on using this style of collimator. It's a piece of cake to use!