The aim here is to be able to control a cheap laser galvo to produce laser shows effects such as drawing complex figures. To do this, I plan to characterize one set of galvos, to understand what affects the position of the laser beam and thus how to control the inputs to produce the desired output.
I plan to do this by commanding both the mirrors and the laser and capturing the resulting picture with a camera. Let's say we scan the x-axis mirror from left to right, starting from t=0. This will move the dot across the projection screen from left to right. We can then find the x-axis position at time t=1 and time t=2 by turning the laser on between t=1 and t=2 (red section in diagram below) and using a camera to capture the resulting drawn line.
I'm pretty sure I can capture this accurately with an RPi camera