Two Dots on top right Corner

Hey Guys, it’s me again.

For those who doesnt know, i’ve got the OMTech 80W Blue Laser 50cmx70cm with Ruida Controller, Auto-Focus and adjustable bed height.

When i received the Laser the first thing i made was the Mirror align Test. The Mirrors were not even close to 90% aligned. Well but nvm now.

I aligned all the mirrors as close as i could to 100% hitting the middle.

The Problem:
In the top right corner, If i engrave, cut or do a test-fire, i’m getting TWO burning points on my workpiece, which keeps happening till moving 25cm further left. If i do a test-fire or w.e there, there is only one dot, which is correct.

As is found out, If I go to the bottom right corner I still get two burning points on my workpiece. Inbetween the top right and bottom right corner I get double burning points. On some spots there is only one but if I go a little lower or higher on that axis I’m getting two.


I already checked my lens and stuff, cleaned it, cleaned mirrors. In my mind, this cant be a “dirt” issue because it doesnt happen on different positions.

If i do a test-fire in the top right corner, and put a tape on the mirror bracket hole, the laser is firing 99,98% in the middle of the hole and its only one burning-hole in the tape (TBH it could be two but the laser burns directly through it)

My results for visualisation:

I really need some advice.

Thank You guys

I know that over the past 10 days I have watched a video by this guy

in one of his many videos he mentuion this anomoly in the top right back corner.

I have written to him asking if he knows which video its in…he has more than 300 400 videos so I hope he has some type of content list.

Fingers crossed



Russ is really fast heres what he says about the “Fourth Corner” I cant remember content but I hope it helps


If you go to minute 15 and watch from there, keeping in mind from the start to minute 15 is relly very importnat to understand the issue, that he found :slight_smile:

What type of head do you have fitted ?
What length lens ?
if you do a test pulse with something over the end of the lens tube WITHOUT Lens and without the nozzle ( so just directly down the tube off the last mirror), what do you get ?



Hey @justginbg thank you for your answer.

How can I find out which Head ive got fitted? And how to find out which lens length I do have?

The double beam in one corner makes me think your mirror alignment still isn’t right and the beam is not going directly down the center of the nozzle. Part of it is reflecting off the inside edge of the nozzle which gives the second dot.

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Man there are so many heads, send an image and lets see if I or someone else recognizes it, and go online to google images and see what you can see.

If you are happy and confident to take off the tube that comes off the head an which the beam travels through to the workpiece, then thats where the lens is mounted.
Measure the gap between your material when focused and then when you measure the distance from the lens to the end of the laser tube nozzle and add it to your focus gap it will put you in the ballpark as to focal length. Namy times its a two inch or 2.5 inch fitted as standard but its good to know :)… :slight_smile:

the head doesn’t really matter.

Your third mirror/lens tube isn’t perpendicular.

The beam hits the third mirror dead-on in the middle, but the beam exits the mirror on an angle, resulting in it catching an edge and reflecting.

Your lens tube ‘should’ be perpendicular, but that’s down to the QC at the factory that assembled it.

The fix is to work out which direction it is angled towards and adjust a pair of mirror screws to move it in the opposite direction.

If you’re lucky, it’s in the X-axis plane and you adjust the two lower screws a fraction at a time. If you’re unlucky and it’s in the Y-axis plane, you need to adjust the left or right pair - upper and lower - to achieve parallel beam.

Always perform your adjustments at the furthest point - lower right, in your case, as it is the widest point of deflection in the beam’s path.

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