Laser weaker during some movements

I’m operating a 5.5MW diode laser on a makerbase mks dlc v2.0 controller.

Overall results are fine but I noticed that the laser seems to be performing worse during specific movements. In the picture, you can see that top left and bottom right of the circles are good while top right and bottom left are a bit weak.

I don’t think this is a levelling issue as the circles you can see are all <70mm in diameter.

Any idea what might be causing this?

It’s a focus/level issue.

Your bed isn’t dead flat to the datum of the x and y axis rails.

Diodes have a tiny sweet spot. Half a mm out can be the difference between go and no-go.

If you can’t get the level spot-on, a longer focal-length lens can help, as it will have a longer sweet spot. G7/G8 lens is much longer than the usual G2.

A glass vs an acrylic lens will also make a difference. The G8 loses about 10% of its power over a G2, an acrylic vs glass loses about 15%.

So, put in a glass G8 to replace an acrylic G2 and you’re ahead of the game (5.5W - 15% vs 5.5W - 10%)

If you have a glass G2, the G8 will result in a bit less powerful beam

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Higher power diodes use an array of emitters, not just one, so the output is a line with the hottest spot in the center.

If the laser is moving along the direction of that line, it tends to pre-heat the material a tiny bit before the hottest spot gets there, giving you a little power boost in one direction that you don’t get when traveling at 90 degrees to the line.

From your picture, I’d guess your beam is at an angle, like this: /

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Thynk you both!

@Bonjour This would be something like this, yes? 1pc Triple Verglasung Mit Schwerpunkt Objektiv Kollimierenden Beschichtet Glas Objektiv Blau Laser Diode 405nm 450nm Langlebig|Objektive| - AliExpress

@LightBurn I think you might be onto something. When trying to cut, I noticed that vertical cuts are not as good as horiznotal ones. That would support your hypothesis, correct?

Unfortunately, there is no easy way to adjust this degree.

Yes, it’s very common for diode lasers just because of how they are made.

No, that’s junk.

Get a G8 glass lens

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