I've shelved this project so many times I thought it would never get anywhere. The main issue has always been that I wanted to keep it simple, but at the same time the math required synchronization between the polarization filter that is spinning and the camera that has to take pictures at very specific intervals.

So what do you do when you don't want to modify a camera to use an external trigger and keep the build simple but the math doesn't allow you? You change the math!

I posted a quick run through of the math in the project details, it probably needs some further explanation but I'll do that in the form of a Python/Jupyter notebook. In the end, I removed the requirement for synchronization which allows me to use a simple motor and a freerunning camera. I have the polarization filter trigger a button every 180 degrees, which is fed directly into the raspberry in order to store the times of these triggers. I then interpolate to get the predicted angles for each frame and calculate the polarization parameters from there.

It just got dark when I finished the build, so the first images will have to wait for tomorrow. Fingers crossed