Pro 25mm beam combiner red dot alignment

[MitchL]

I have one of the beam combiner mounts:

http://www.lightobject.com/Pro-25mm-bea ... -P872.aspx

The red dot laser is nowhere near the center of the mirror. I haven't installed the laser particularly deep in the tube, should I be putting it as far into the tube as possible?

/Mitch.

[Tech_Marco]

When you say "mirror" which mirror??? First mirror, second or the last one? Or the mirror on the beam combiner...

When asked for a question, please be specific or I have hard time to reply you guys.
So many folks asked "Don't work" and without more information, I really can't do my job
I don't want to 'guess' as either it make things worst or taking longer to get a solution right the way.


Marco

[MitchL]

Oops, sorry Marco, I should be more specific. I can add a photo later this evening when I get home.

When you say "mirror" which mirror??? First mirror, second or the last one? Or the mirror on the beam combiner...

The beam combiner has the tube/stand, which holds the red laser pointer, and the reflecting mirror assembly at the top.

I expect the red dot to be visible more or less at the center reflection mirror (regardless of the adjustment of the mirror).

I've marked up my CAD model, see the picture below:

I've noticed two things about the red laser that comes with the combiner:

- It is not focused as it comes from the factory.
- I can bring the beam into focus by turning the top of the unit.

If the beam is centered in the vertical tube, I would expect the red dot to be visible in roughly the center of the reflection mirror. That would be ideal since it would also help for general laser alignment.

The combiner's mirror adjustments would be used to get it to the center of the next mirror (fixed reflection in my case).

In my question, I am talking about the beam combiner's red laser dot and its visibility on the beam combiner's reflection mirror.

Sorry to have not been clear before!

/Mitch.

[Tech_Marco]

It is nothing wrong with the combiner. We tested it before making production. What you need to do is to move the mirror/lens holder up for 2~3mm up but not totally secured it down to the mount
See pictures attached. It is very simple to do and you will get perfect center hit on the mirror

Also, the laser pointer focus point is adjustable. If it shoot at the side way, just turn the pointer either left or right then by adjusting the gap level, you will get the center dot


Marco

[MitchL]

It is nothing wrong with the combiner. We tested it before making production. What you need to do is to move the mirror/lens holder up for 2~3mm up but not totally secured it down to the mount

I never said anything was wrong with the combiner - I just want to know how to adjust it properly.

(although, there actually _is_ something wrong with mine, but it's an easy fix. One of the silver M4 screws with the spring underneath is badly bent. I have plenty of screws to replace it).

See pictures attached. It is very simple to do and you will get perfect center hit on the mirror

Yes, I see that, and my mirror is mounted with a consistent gap from the body. I will measure it to 2mm.

Remember, I'm not talking about where the red dot is reflecting _to_ - I'm talking about the place where I see it the red dot hit the mirror from the back side.

Also, the laser pointer focus point is adjustable. If it shoot at the side way, just turn the pointer either left or right then by adjusting the gap level, you will get the center dot

OK, I'll double check my installation.

My original question stands - how far into the vertical tube do you expect to insert the laser?

/Mitch.

[Tech_Marco]

No special rule applied but personally speaking I preferred 1 inch away if possible. If the mount got hot, then leave more room


Marco

[Tech_Marco]

Mitch:

How''s the combiner doing? Did you fix it yet or still having out of center alignment issue? Please update


Marco

[MitchL]

Hi Marco,

I've been fighting with it, but I think I'm winning.

Here's what I think I've been dealing with - I took the combiner off my laser to move the pointer further into the tube. I put some sticky tape on the top of the tube to see if the pointer is centered in the tube-- it is not, as you can see below:

By wiggling the laser pointer a little and using a set screw to hold it in place, I've been able to get it reasonably centered on the tape. Reassembling everything, the dot now appears right in the middle of the combiner's reflection mirror. (this should require no adjustment as long as the laser pointer is centered in the tube). I haven't proven that the laser pointer is centered in the tube, but I feel it's pretty close now.

I think I'm in good shape.

I'm at the stage of my laser's design where everything's mostly working, and I'm trying to align all the mirrors before running my first job. The combiner/laser pointer is not as useful as I had hoped for CO2 laser alignment, at least not yet - once I can adjust the combiner's mirror and the height of the CO2 such that the output of the combiner is exactly the same as the CO2, the rest of the mirrors should be easy to adjust. I have a plan for this, hopefully it'll work!

The LO products have been excellent so far, thanks Marco! I really wish you had CAD models though!

Off topic a little, here's the current status of my laser:

Early system tests: https://www.youtube.com/watch?v=nyGHMwixa-4
Laser firing: https://www.youtube.com/watch?v=cpxBAPBsdGQ

/Mitch.

[Tech_Marco]

Great to hear you have good progress! Trust me, you will get to the point you want. Just be patience with yourself and me. I may not sounds patience but I'll help you to the most. Period.

I wish I have the CAD but I can't get those. It is not me to make it but we come up an idea and let the tooling shop product it for us. They don't want us to go other shop so they kept all doc and drawing. That's the way how they do business in China! When you asked them to provide drawing, not even precise enough for production, they will refuse it. That's why sometimes I'm so pissed (not to the customer but to the part provider) when some customers asking me to supply them drawing and mad when I said I couldn't. It's not me who doesn't want to provide those drawing, it's those fxxxing tooling shops are not willing to share CAD file. I don't know what's matter with them. A simple drawing won't be a big deal for them, right?! Well, if we have to do it we can but it will cost me because I have to hire someone to do the CAD. Be honest, I can't afford it or I have to raise the price which I don't want to do see it happen. I want to make DIY affordable and share the fun.

Let me know if you have any question or problem for your project. I may not be able to reply you immediately but I'll try my best.


Marco

[MitchL]

No worries, Marco - I'm not at all disappointed or angry with you - this has been a super fun project, and without LO I would not have been able to do anything at all. Thanks for everything you do for us.

Didn't realize CAD was such a hot button - I'll not press that one again (so you can keep your blood pressure down!).

This is the wrong topic to ask, but while I've got your attention: I'm interested in your new LO-branded DSP. Do you have any measurements for the control panel? If I'm clever I can plan the front panel of my current laser to make it an easy swap when the time comes (you can answer over in the other topic). I'm in the process of designing the exterior skins of my laser, so now's the time for me to make any adjustments.

/Mitch.

[Tech_Marco]

It's OK. I sometimes can't control myself. I think I received too much unfair treated by those tooling shops in China.

I'm heading back to office and I'll make some measurement. I should have the new color DSP card in next two weeks as the front panel is completed. FYI, this time they use a plastic enclosure to host the connection board. But the main brain is installed in the same compartment as the LCD. I'd metal box better because it provide a layer of protection for the EMF noise


Marco

[baccus61]

Hi Mitch,
If you can, try this.
Fire your laser at a target about 1-2meters/yards away onto a piece of wood or thick card and then align the red pointer to the center of that burn mark which will be around 1/4" or 6mm. Check at the tube end and then at the distant target so you get the beams coincident. You may need to go back and forth a few time to get it right. That will make setting up your mirrors so much better and easier. Don't rely on the laser pointer having a beam that is aligned with it's barrel as most are not good enough for what we want and you will get a parallax error with the beams. It might be in the middle at the front of the tube but may be 4" off center at 1 yard as the beams cross each other.
Let me know if this helps. That's how I do mine and it works a treat.

I just had a look at your setup and it's looking great. Just remove your first mirror to try what I said and see how you go. It doesn't take long and you can guarantee the beams will be aligned.
regards Rich.

[MitchL]

Hi Rich,

Funny you should mention that technique - that's *exactly* what I was doing last night, though I was less than a meter away.

I removed the #1 mirror and placed a target about "far" away (it was probably less than a meter).
I also constructed another target that I can place 2cm from the output of the beam combiner.

First step: with the *close* target, I turn the red dot on and fire the laser. I adjust the laser tube itself such that the red dot is centered in the burn mark from the CO2.
Next step: I remove the "close" target and fire the laser at the "far" target. This time I adjust the mirror in the combiner such that the red dot is exactly in the center of the burn mark.

Repeat a couple more times to make sure near far have their red dots centered on the CO2 mark.

Theoretically, this means the two beams are co-linear. Now I can replace the #1 mirror and use the red dot to get everything aligned.

I believe what I just described is your exact suggestion to me, so that tells me I'm on the right track!

What I may be doing wrong is that I need to get the far target much further away (for example, I should choose the approximate max distance the laser travels to get to the head, about 1500mm in my case. I'm sure that will help.

I'm still trying to get the alignment to be correct but I can't get things to line up in both axes. For example, if I leave the Y axis alone and use the #1 mirror to adjust the near (X-) position and the #2 mirror for the far (X+), I can get the beam exactly centered in the head. but once I move the Y. the laser's so far off that it doesn't hit the #2 mirror anymore. I've been watching various videos on youtube. Since I have a red dot, it does make sense that I work my way out from the laser towards the head - I'll print up a crosshair target to mount on the gantry and see if I can get the #1 mirror to hit it consistently. Then I can move the crosshair to the head and adjust the #2 mirror.

Despite minor frustrations, this is the fun part of this project!

Thanks for your suggestion! More please .

/Mitch.

Hi Mitch,
If you can, try this.
Fire your laser at a target about 1-2meters/yards away onto a piece of wood or thick card and then align the red pointer to the center of that burn mark which will be around 1/4" or 6mm. Check at the tube end and then at the distant target so you get the beams coincident. You may need to go back and forth a few time to get it right. That will make setting up your mirrors so much better and easier. Don't rely on the laser pointer having a beam that is aligned with it's barrel as most are not good enough for what we want and you will get a parallax error with the beams. It might be in the middle at the front of the tube but may be 4" off center at 1 yard as the beams cross each other.
Let me know if this helps. That's how I do mine and it works a treat.

I just had a look at your setup and it's looking great. Just remove your first mirror to try what I said and see how you go. It doesn't take long and you can guarantee the beams will be aligned.
regards Rich.