I'm just thinking of using CD Plate as encoder wheel.
For those who tried to make "scratchable" digital dj console, always search for rotary encoder that have somany pulse per rotation.
Ok, here it is :
1. Encoder Wheel Generator : I Found http://www.thingiverse.com/thing:1527
will do the job. It will generate the patern as PostScript file.
a. Make sure that the outer diameter is 3.5 inch .. or alternatively you can also write it in mm.
b. make sure that the Long and width of the page is also 3.5 inch , and all margin is 0.
c. Other configuration ... please read the script it self.
d. open the ps using your flavor of image editor that can open PS and save it as Bitmap ... let's save it as "ew.png"
2. LaCie Labeller ( http://www.lacie.com/us/support/drivers/index.htm?id=10008
This is the tool to do LightScribe ....
LightScribe is at http://www.lightscribe.com/
Create new label with it, Import our generated patern image to it ... and allign.
Originaly, lacie is use to "burn" bitmap picture to the "label area" of the plate ...
That is they said "burn, flip, burn" ... what we do is the second burn.
But rather than fliping it .. we just burn it to the data area of the plate ... remember to use New Plate.
This way ... the writer will "destroy" some reflective layer of the plate .. but it do it based on our generated patern from Step #1.
I Still have a question : What is the dimmension of "black" and "gap" that acceptable by the sensor ?
I think we can get 2000 pulse per rotation encoder wheel ... as long as it is acceptable by the sensor.