Lines interrupt when burning

In Lightburn I created a square with lines to adjust the focal point. While doing that I noticed that the lines interrupt while burning (see attachement)

Could this only be a problem with the focal point or could there be any other problems?

Thanx for your help…

Hi Rudi, what is it supposed to be?
Could you add a screenshot of the art work and the settings? I suppose you use line?

It’s likely because you are using a diode laser with white paper. Because diode lasers use light in the visible spectrum anything that reflects that light won’t work well. White paper is a prime example of this - it will initially reflect most of the light but as it heats up it’ll start to char a tiny bit which eventually helps things along. But move to a new location and you have to basically start all over again.

Cardboard is a much better option for doing tests like this. I’ve also had a lot of luck with cheap construction paper.