Wow so many feedback!
As I thought, it is out of my field to actually change the mechanical motion. However, the ultimate goal is not to actually change the polar coordinate system to a Cartesian coordinate system but just to gain control of the way pits and lands are created. It is my fault that I stated it poorly in the opening post. Actually, I want to be able control arrangement of the the pits and land structure so that it is not aimed to store data but to create some sort of physical geometric shape. ie - arrange all the pits to spell a word.
@VE1BLL: Actually that might be quite helpful, I will look into it
Thanks you all!