When creating my one figure, how to stop flashing

This depends on several things:
First of all your laser system must be capable of displaying the number of points you want to be drawn in a reasonable way. The second thing is, that you can adjust the scan speed and the scan parameters in the software to match the scanners in your laser projector best.

There are several tutorials:
Laser output quality optimization:
www.showeditor.com/en/tutorials-faq/tuto...ty-optimization.html

Adjust scanner settiongs, set the correct scan speed:
www.showeditor.com/en/tutorials-faq/tuto...-scan-rate-kpps.html

The number of "characters" you can display at once without flickering is limited by the capability of your laser system. The more professional the scanners, the more points you can draw at once without flickering.