Mirror alignment. 80w CO2 laser red/Black Ruida controller

I’d expect it to be round, not oval…

Can you do this again, with less power. Keep the middle from being black…

You want to see the power distribution within the beam…


this was done with 13% power this morning. Sam

Hi Sam,

How is your mirror alignment going?

If these are from mirror 1 then they all look fine apart from number 1 & 7.

Have you started to burn targets placed at the 2nd mirror?

Move the Y axis/gantry to the back so the first two mirrors are close together for a start and use a bigger target at mirror 2 (to start with), then as you dial in the fine position of mirror 1 you can start to move the 2nd mirror further away, until you have the burn in exactly the same spot when the 2nd mirror is close and at max distance away.

I personally like to use a small square of clear acrylic as my target medium, it usually is 3mm thick and large enough to cover the mirror and beyond so I can blu-tack or double sided tape the mirror to the black mirror surround, that means the mirror won’t require cleaning afterwards and I can get quite a number of pulses in before I need to replace it.

If I don’t have any clear acrylic on hand I’ll use a nice wide masking tape but place a new piece over the last piece so it wont burn through as much, putting a new piece on when it gets a bit hard to read where the last pulse went. I keep doing that until I cannot easily see the circular indent of the mirror position showing through the tape.

Hi Nicholas.
I have been communicating with Jack Wilborn, he wasn’t happy with the first results i sent him he felt the laser holes were more like donuts and asked me to do it again so this is from this morning’s effort, my feelings are they still look oval not round round, the power was set at 13%, I tried lower but the laser would not pulse at the lower power.
I haven’t started to burn targets at the 2nd mirror yet as I was waiting for Jack Wilborn’s comments on the oval shape the laser is burning. I am nervous at this stage as the whole repair of this Laser has been ongoing for 3months now and i don’t want to go backwards. I am waiting on 2 new sensors coming from the U.S. as they were damaged when the laser crashed into them and knocked them on an angle, that problem is now solved and we can now move on to the Mirror alignment
I do have some clear 3mm acrylic and I can do another test today I will place it on the first mirror and burn so you can see where i am and check the holes if they are round or oval.
I will do this shortly and post my results for your comments. thanks for your help. Sam

Don’t be nervous, the burn spot looks fine enough to me, sometimes they are a bit like a donut until you increase the power.

Hi Nichlos heres the result for your critique Sam

Is that with the acrylic square on directly in front of the tube? If so it does look a bit oval but could be worse, so since there is not much you can do about it you may as well continue with the alignment and see what the spot looks like by the time it gets to mirror 3, and then see what sort of power you get when cutting.

Hi Nicholas … I put two large pieces of tape at the second mirror and moved the laser to the lower lh corner and fired a pulse, nothing happened, then moved the laser to the top lh corner near the laser tube and fired a pulse, still nothing, removed the tape and put it over position 1 and fired a pulse and got a burn mark… what now

Make sure mirror 1 is clean, and put a large piece of cardboard in front of mirror 2 in top left hand corner. The laser has to go somewhere.

I’d also look at the mirror for condition. Hopefully it’s not burnt.



i havent pulled the mirrors out yet just cleaned the front lens but that made a big difference, will pull the mirrors out and check… Sam

will have to start the mirror alignment next, its showing SLOP on the Ruida panel at the bottom of the machine so need to correct

You said it is firing on all lens in the middle, does that mean you have laser going all the way past mirror 3 and through the nozzle?

You are likely to keep getting ‘slop’ errors until you replace the faulty Y axis home sensor, just ignore them for now.

Thanks Nicholas ,yes it is firing through all three mirrors through the centre and down through mirror 3 and through the nozzle. i want to pull the mirror lens out now and check properly to see if they are damaged in any way,
just received my first new sensor from the Post, ordered two so next one should be following

Try to inspect the mirrors in situ, removing them can easily cause the alignment to be changed, and any unnecessary handling of the mirrors (or focal lens) creates the opportunity to accidentally scratch or damage them.

Did you place a piece of masking tape at the bottom of the nozzle? how centered is the (low power) burn-through spot compared to the small circular indent left by pressing the masking tape to the nozzle?

If you attach a small piece of clear acrylic in front of mirror 3 and then pulse the laser with the nozzle in each corner of the machine - you should get 4 burn spots with each spot landing directly on top of the previous one? (inspect them as you go starting at top left and finishing top right).

mirrors in situ, sorry already took them out to clean and replace, they don’t appear to be damaged , but i intend to replace them anyway 3years old.
masking tape at bottom of nozzle, NO
attached tape to mirror 2 top and bottom fired pulse landed in same spot both shots.
attached small piece of acrylic to lens 3 and fired a shot very weak mark because machine is at 13%,
havent tried acrylic in all corners yet

Hi Nicholas. after removing the mirrors and cleaning them with isopropyl alcohol they look ok to my mind,
I see online that many people are saying no need to replace these mirrors that came with a 80w Chinese laser what’s your thoughts on this.
how shiny should the mirrors be, are we talking about looking like chrome plating shiny or just clean, this is all new to me… Sam

No need to replace if you don’t see any damage. If you see a burnt spot then it’s damaged.

The mirrors don’t always look as reflective as shiny chrome but should not have any uneven dirty or cloudy looking patches.

Every 4-6hrs of heavy use mirrors and lens should be inspected and gently cleaned if necessary - especially mirrors 2 and 3. Try taking a close up photo of the mirror so we can see it. It never hurts to have a spare set of mirrors on hand.

IPA is generally not recommended for cleaning mirrors and lenses since it can be quite harsh on some mirror and lens surface coatings. I find that multipurpose lens cleaners made for glasses, mobile phone screens, camera lens and plastic safety glasses are usually pretty good.