Alignment question.

[laserLips]

Hi all.


I’m rebuilding my projector and swapping the order of lasers round to now be Blue, then Red, then Green.

The Reds are maxyz’s and from the way they are put together I am not going to have any movement in them for alignments. The blue and green will be adjustable and so will the scanners/optics.

Do you think that even though the reds are second in line, I should put them in first, and then the scanners and then the lasers? Or should I just put the green in first and then the reds.

Like I said the reds will not be adjustable, once I have drilled the holes to put them in, that is where they are staying.

Thanks,
Graham

[Zoof]

From what you are saying should should get away with it, given that the laser apertures are about at the same height.

Maybe its best to exemplify.
The pic attached is my setup. Note that the blue and green are bolted down, the green is adjustable through the mirror and the blue is non-adjustable. The red and galvos are adjustable.
My alignment procedure goes somewhat like this, with all laser on (low power):
adjust the right-most mirror mount that reflects the green so that the green beam crosses exactly the blue one on the blue dichro. The adjust the blue dichro so that the blue and green beams are aligned perfectly. Position red so that it hits the dichro exactly where the blue and green hit it. Then align red dicho to align the red beam with the other beams. Then position galvos so that the beams hit it perfectly. Voila.

hope this helps ya.

[mixedgas]

A possible quick check, is the nearest neighbor test. Make a precise pinhole in a metal block at the height of the lowest laser. Put it close to the last combiner, before the scanners. If you can get all the beams through the hole, and get them in roughly the same spot in the far field, your close. If you don't have decimal size drill bits, I'd use a 1/16th or 3/32nds

Large professional projectors usually have two pinholes, one at each end of the beam rail. This way you can quickly realign a laser if you remove it.

Even to this day, after years of aligning lab lasers, I still stock a few pinholes on mounts. It really helps.

Steve

[buffo]

Graham;

So long as your other two lasers are adjustable you will be fine. There's no need to change the order of the lasers on the optical table. As long as the reds are mounted high enough to be at or above the lowest possible height of the other components, you're all set. You just need to shim the other components up to the same height then.

First you'll need to shim the green laser so that it's beam hits the point on the first dichro where the red beam reflects off it. Then you'll need to shim the blue laser so that it's beam hits the second dichro where the yellow beam passes through.

Oh, one more thing: Make sure your scanner block will mount low enough so that the combined beam will hit on or above the mirrors. (Again, shimming the scanner block *UP* is easy, but it's hard to *lower* it if it's already flat on the table.)

Adam

[trwalters001]

A possible quick check, is the nearest neighbor test. Make a precise pinhole in a metal block at the height of the lowest laser. .... If you don't have decimal size drill bits, I'd use a 1/16th or 3/32nds. Steve

Hi Steve,
I have decimal bits. What is your recommended size for these pinholes?
Thanks!
Tim

[laserLips]

Adam good to see you back.

Here's where I'm upto.

The green is slightly adjussable and so is the mirror
The reds are NOT and NEITHER is the dichro
The blue is slightly adjustable but the dichro is not.

Im having a hard time making the green hit the red at the same spot on the dichro as well as hitting the scanner block. I need to reposition the scanner block I think.

I have all day tommorrow to do it so hopefully by tomorrow eve I'll have it done.

[allthatwhichis]

The green is slightly adjussable and so is the mirror
The reds are NOT and NEITHER is the dichro
The blue is slightly adjustable but the dichro is not.

You're on crack then. You need some movement ability to align, or a set of mirrors. I like the mirros method as you can have your lasers at any height. You have them on moveable tables... That makes them adjustable, I think.

[mixedgas]

a usual beam diameter is between .5 mm and 1.1 mm.
So you pick one for your beam diameter, I usually go as small as I can.

Steve

[allthatwhichis]

Since you have not settled on a layout, check out these two posts...

http://www.photonlexicon.com/forums/...5&postcount=99

http://www.photonlexicon.com/forums/...&postcount=110

You may rethink the 90 and 45 degree angle set up.

[laserLips]

You're on crack then. You need some movement ability to align, or a set of mirrors. I like the mirros method as you can have your lasers at any height. You have them on moveable tables... That makes them adjustable, I think.

When I say not adjustable I mean moving around on the base plate. I can of course change the pointing direction of the dichros, but what I mean is they are drilled to the baseplate and can not be moved.

Waiting for a new mirror from Rob, so this is on hold. Giving me a headache anyway.