As I have not yet seen this in any mod/tech tutorial I must assume that it doesn’t work. However please endorse me and explain why this should not work as I don’t have the knowledge to understand the principles.
What about mounting a red dot pointer close to the first or second mirror and align the light parallell to the laser to get red spot through the nozzle?
Why would this not work?
I’ve considered this & to be honest am still thinking of a solution to do just this.
The problem with it is that in order for the red-dot-pointer to not get hit by the laser beam it would have to be aligned/angled slightly away from the laser beam. This in turn would cause the angle of reflection of the red-dot beam to then be different to the angle of the laser beam. All in all, it would not follow the same path & more than likely not even end up coming out of the lens.
I have been thinking of methods to do pretty much what you have suggested & the only one that I can come up with that might work is something that raises the red-dot-pointer perfectly in line with where the laser beam exits the tube. So you would have to raise/lower it when you want to use red-dot or actual laser tube.
try reversing the laser send the beam up through the lens with a target on the tube
@Dennis_Fuente That’s an interesting idea, but I think Purple’s point is to have a dot show on the workpiece where it is going to hit.
I’d wonder too whether sending the beam through the lens in the reverse orientation would cause the beam to disperse/defocus & when it reaches the tube to show position it would maybe be a large circle rather than a dot?
Another option that may work is some kind of beam refraction through a prism. It may be possible (although I’m not sure of the physics behind it) to have main laser beam enter like so:
----> PRISM —>
and exit in a straight line.
Then you could have the laser pointer beam entering perpendicular like so:
|
|
PRISM----->
and exit at 90 degrees.
If it was possible to do this with the same prism, which I can’t recall from physics class years ago, then maybe it can be done very simply. Also, the prism would have to absorb minimal of the laser energy as the beam passes through.
Are you trying to make a d-i-y of a beam combiner (& lens) so you can run the LED pointer along the same light path of the CO2 laser beam? You can get those from LightObject likely cheaper than making it yourself.
So, if you want the beams to both be active at the same time, you need a beam-combiner (it’s a mirror to visible light, but it lets IR pass through – http://www.lightobject.com/Pro-25mm-beam-combiner-mount-with-laser-pointer-P872.aspx – including housing and red laser).
OTOH, if you’re cheap and don’t mind the red dot going away when you lower the cover, you can print my thing on Thingiverse: http://www.thingiverse.com/thing:1002341
When you shut the door, it lifts out of the way of the beam. I put a swatch of aluminum on the backside because I periodically forget and press the “test fire” button when the red laser was down (smokes the wires).
@Yuusuf_Sallahuddin_Y Yeps, that’s what I was wondering about.
@Jim_Hatch Cheers for the feedback
@Thor_Johnson sweet adaption of the key koncept of my question. Does it work well? how do you align it between lid openings? Easy adjustable that stays put?
Ok, that print from Thor looks like a great idea. Anyone have a 3d printer that would be willing to make me one 
@Carl_Fisher Either that or look for a local hub on 3D Hubs or Shapeways. Can get small prints done reasonably cheap & pickup.
@Thor_Johnson I had previously seen that design on thingiverse & couldn’t figure out what it does or how it works. Now I realise given the context of this conversation. It is actually perfect for the job.
Never new about the mirror that lets visible light reflect & IR pass through it.
@Yuusuf_Sallahuddin_Y Well what do you know, I found a 3d hub right in my home town. I never knew about that service. Thanks for the heads up
@Thor_Johnson What is the case version of the STL on Thingiverse? Looking at it I can’t see what those cases provide.
@Carl_Fisher You’re welcome. Someone else here put me onto 3D Hubs, so it’s only fair to pass it along. Also, if you look on my profile, there is a refer code for 3D Hubs that will give you US$10 off if your order is US$25 or more.
Good to know. I did place an order with a local hub bit it only comes out to about $11 for that part.
@Carl_Fisher Case version?
Mine was just a little wobbly when I snapped it into place, so I put a dab of gorilla glue on each end, and it’s rock-solid now (you have to bend the sheetmetal and slide it back and forth for it to align perfectly, but it is possible). Be aware that nobody puts effort into aligning the laser pointers, so if you have to replace it (or rotate it), you have to realign it (as I found out when I smoked the wires). I’m just powering the pointer from the 5V supply on the laser so I’m glad I didn’t accidentally short it out :0, so do put a bit of aluminum on the backside (you can see mine held by the electrical tape that holds the wires), so you don’t accidentally smoke and have to replace it.
I have a spring from a ballpoint pen in mine, and it’s rock-solid as far as coming back down and making a dot anywhere. Because the beam is so small, you can’t see the focus (so I made an L that I balance on the head and use that). But it’s a real treat for aligning jigs – I do the initial setup, close the lid and burn 2 dots at a known X,Y of 100+mm apart using the test fire. Now to reposition the jig, move to the first position, and twiddle the jig until the red beam “falls in the hole”, move to the 2nd, and repeat until it falls in both holes, and now the jig is aligned!
Yep, and if you don’t have a local hub, I’d be glad to print something for anyone and drop it in the post (at least in the US… international shipping would make the price insane)- http://www.3dhubs.com/atlanta/hubs/thor
@Thor_Johnson meaning when I pulled the files from Thingiverse that you provided above there was a LaserTarget.STL and a LaserTarget-NoCase.STL. The first version has some weird case/blocks around both ends of the arm while the other does not.
Oh ok. Now I remember. When I was modeling it, I put blocks up for "Laser-Target Plate " – the thin rectangular plae, “Keep Out Area” (where the mirrors are - the big block), and where the lid hit (block that is intersecting with the D shape at the end). I originally did this in Solidworks, but I figured I’d put the one with the blocks in it up on Thingiverse so you can see how it worked… but I suppose that is confusing since there wasn’t any context (par for me).