2 Axis Mirror Galvanometer

by timogiles Nov 7, 2013
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Could you please do a tutorial (or just elaborate) on this? I am looking all over to find out how to make my own but I have had no luck. I am mainly looking for how you control the coils. Volts, current? Anything would be helpful!

I am driving the coils with a full bridge driver for each coil. I use a microcontroller to output a PWM signal to the full bridge drivers. You could also use an opamp and a DAC, but the opamp would have to be able to handle quite a bit of current. My coils ended up being 5 ohms and I'm supplying the bridge driver with 6V.

Very good looking machine!
And a slightly scary powerful laser (I'm one of those persons that are easily scared by lasers)

But I can't help wondering if some of the accuracy issues might be caused by the x stage moving the y magnet relative to the y electro magnet?

I should have added a PSA to my description, I only have the laser on when I'm wearing my laser safety glasses. Anybody who starts playing with lasers should not even power one on until you have the appropriate protective gear!

I think the accuracy issues that I alluded to are from the acrylic hinges. This design requires them to have a spring effect that wants to center the mirror. After being bent in one direction spring force seems to relax a little bit. But to your point, I did notice that when i was gluing in my magnets the second stage that i glued had a little bit of rotational force like they wanted to align to the ones already glued in.

If the accuracy issues are caused by the other magnet pair perhaps one could print an array of dots.
Manually "aim" the laser at the dots and write down the deflection power required in an array, and then do some simple linear interpolation when driving the coils.
I also suppose that one could/should take the moment of inertia into account if one were to do high speed moves.

With regard to the spring perhaps another more distant/weaker magnet pair could be used to centre the mirror instead?
(Would ruin the otherwise clean and simple design, and would probably be very non linear with regard to deflection)