Save the result (right-click and save-as) and import into Beam Studio. Do not adjust the size of it after it is imported! If you need to change the size, you need to re-dither it.
This is because changing the size means you need more or less pixels. But if you simply stretch it in Beam Studio, you are just stretching or shrinking existing pixels, but the laser beam can't change size!
Also, if you don't like the result, adjusting brightness inside Beam Studio won't work. Adjust the brightness before dithering. This is because changing the brightness of each individual dot does not help, you need to change how many dots and how scattered they are.