Before I go into weekend relaxation, I would like to discuss, what I got so far.
I was briefly searching for off the shelve encoder discs, without luck so far. Also knowing, that glass tends to shatter, I'm either looking for plastic or metal discs. Finally, I think they could be custom made, with photo etched lines.
Just for looks I made 800 lines on a 50 mm disc, but I think 900 lines and quadruple sensor would be best for 0.1 resolution.
I also found in my stash 4 mm shafts and 2 linear ball bearings (NB SM4G). Bearing OD is 8 mm length 12 mm.
If I place 4 discs in a circular pattern, I come up with a head of slightly over 50 mm diameter.
I placed 4 linear shafts, 2 each in a 8.1 mm offset in order to clear the other bearings and came up with a stroke of 14 mm.
For nozzle rotation and vacuum seal I like to use tapered discs, pretty much like piston engine valves. Here we would need to experiment with different materials and find how long they last.
Also, I will have to get my hand on a Siplace nozzle and take dimensions.
So far, I have no motors yet. Small DC servos come to my mind. However, if we want to be affordable, we need to look elsewhere than Maxxon, Escap and Faulhaber. I may look into the Canon catalog, any other suggestion?