I wonder if you could just tear the controller out of a CD/DVD drive and build a new one from scratch, kind of like the new floppy controllers being used now to read the raw magnetic data. You could just command the head to move to the center, find the beginning of the data and just keep reading until you hit the buffers.
Floppies (most of them, anyway) have fixed track widths, and these tracks are arranged cylindrically, and these cylinders align with the steps of the stepper motor that is used to actuate the head assembly.
It's relatively easy, with the right ratio betwixt step advancement and track width, to get the head moving properly on a new implementation of a floppy controller. Want to read track 1? Step to the head N times to reach track 1 from wherever it started, and read it. Next, want to read track 33? Step the head N times to track 33, and read that.
But tracking the spiral groove of a CD is a very different problem to solve. Steps tend to lose their meaning. Instead of electromagnetic steps, it involves 3 different laser beams: Two to continuously keep the head centered where it needs to be on the ever-changing groove using a servo feedback loop, and a third to read the data from the pits and lands from the middle of that groove.
Is it do-able? Sure! People with far less advanced tech than we on HN might have laying around did it 40+ years ago.
It's just a very different nut to crack than reading a floppy is, even if the mechanical and optical bits are recycled.
(And that's just head positioning. The pits and lands still needs to be read, and those reflect back from the disc as optical phase shifts, not as changes in magnetic polarity and/or amplitude.)
