I want to spin a dove prism (image rotating prism) around it's long axis at a controlled rate (100 to 300 RPM). The purpose is to get a de-rotated image of a spinning object (by looking through the prism).
The prism is small and light - about 20x20x150 millimeters and maybe 0.1 kg.
My idea is to mount the prism inside a spinning bearing. I tried an inexpensive "pillow block bearing" ($20) and mounting the prism inside, but that didn't work well:
(a) The friction needed to turn the bearing was much higher than I wanted - I want it to spin freely (for example, if I give it a spin with my fingers, I'd like it to keep spinning for a while). I was driving the rotation with a small DC motor with a belt (controlling motor speed with a knob). The friction was a problem.
(b) The axis of rotation didn't seem to be as constrained as I'd like - I want it to really just spin in one single axis that doesn't move around, so the view through the prism stays centered on a fixed point (assuming the prism is properly aligned with the bearing - I'm going to 3D print a fixture to hold it in place).
Can I get a recommendation for the appropriate type of bearing for this? (Or, some other way to accomplish what I'm trying to do?) It would be nice if it's not expensive (< $100).