UV laser pens leave a luminescent trail when shone on glow-in-the-dark material. In this project a 405nm laser beam is steered by a pair of Arduino controlled mirrors leaving a sine wave based trace on a sheet of luminous vinyl. You can see it in action here https://www.youtube.com/watch?v=MUtxg7VziGE and there are some more details on my notes blog here
http://notes.robives.com/laser-galvo/ There are several things to try next:
Writing code to create a raster scan to make a rudimentary TV style screen
Making an oscilloscope or ECG
Using stepper motors rather than servos.
I went with servos because of their easy availability. I'll have a go with he stepper motors next as they are here on my bench but ultimately I'd like to try galvos. I found a cool article on line from someone who has made there own. http://elm-chan.org/works/vlp/report_e.html
First, let me say that using mirrors is a step in the right direction compared to some projects we see here!
Using steppers might work, and I don't want to discourage experimentation if you've got some on hand. You'll be limited in resolution, but with microstepping, it just might work!
But look into "real" galvos. They're a lot faster and more accurate, but they just don't have much torque like steppers or servos. The downside is that you'll have to drive them with accurate voltage outputs, but PWM off the Arduino will work for medium speeds like you're getting with the servos.
#LASER