Are you talking a 20khz square wave (first pic) or 20k points per second?
The scanner will not even think about doing a 20khz square wave forget about 60. We are lucky if we can get a diode laser to modulate correctly at 10k. A really good well tuned pair of scanners might be able to do a two or three k sine at a couple of degrees. Remember we are moving little mirrors that have inertia.
The noise does look a little bit high. Depending on what freq you are trying output you might want to think about a low pass.
I understand that the test output is unipolar but to play nice with everyone else you need to plan on a balanced bipolar output.
Chad
When the going gets weird, the weird turn pro.