A quick laser pointer with a bonus.
I got tired of finding the left upper corner and did a quick fix with a little laser then discovered a bonus function!
As I said I was tired of doing a test fire to find that upper left corner so decided to whip up a prototype laser pointer. I’ve seen two lasers used to get cross hairs but that seemed like way to much work and too much mass.
In thinking about laser coherent light properties. Hmmm… that means there is almost no light scattering so a mechanical cross hair can be anywhere in the beam… up against the emitter… or a foot away and you still should get a crisp and well defined shadow.
I had some cheap emitters from past projects so I pulled one them out to play with. Just like these:
I took a piece of approx .015” wire and cut two short pieces to fit over the front face of the laser diode and glued them down with super glue (I was in a hurry and doing it again I would use 2 part epoxy, less chance of messing up the front lens). You can tell I did even center the wires well but as it turns out it doesn’t matter. I put 3 volts to it… and I’ll be… it works and is sharply defined at any distance.
So still being in a hurry. I took a piece of angled aluminum I had laying around and made a bracket by band sawing it out, a little quick filing and belt sanding. Drilled one hole to slip over a 4-40 screw and be tighten by a nut. Also I band sawed part of the bracket on the back thinning it so that I could adjust it in the Y axis ( fore and aft) just by bending it into position (just in that y axis). The right to left (X axis) is adjusted by loosening the nut and swinging it.
I mixed up some 5 minute epoxy, then setting it aside to thicken some… drilled a few small holes in the inside corner of the angle to act as anchors for the glue. Dropped some of the thickened glue into the corner and being careful not to get glue on the emitter face place it in the corner and adding more glue on the outside. Notice in the picture the base was filed square and glue wiped off those surfaces so I could use a crescent wrench to force the bend adjustment as needed.
I added a cheap 12v to 3v transformer and an on/ off switch I had then turned it on… hmmm?? Nothing no light… traced my wires and OK going too fast… forgot to hookup the little transformer to the 12v power!
It worked very, very well… once power hooked and adjusted. The adjustment consisted focusing the beam height first onto a piece of wood and bumping a burn spot. Then bending the y axis until centered and next loosening the nut and swinging the X axis to center. Burning another spot and readjust as necessary (it took about six burns for me to get it). Ta daa… finished.
Now for the bonus… Because the laser diode and bracket are parallel to the x axis and at about a 30 degree angle they move left or right only when the table is moved up or down, you can just burning a very light spot and move the z table (you do have a power z table right?) until the cross hairs put the beam at focus when the burned spot is centered in the cross hair!
A little trig and rough measurements of the beam diameter to cross hair center can even help you adjust beam center up or down into you work piece.
That’s it for now… pictures below, it was hard to get a good focus on the laser beam it’s dead sharp in real life… someday I might even machine a real bracket and diode housing.
