Final answer:
The groove depth and contour are controlled by rotation speed, error correction mechanism, and the diffraction grating.
Step-by-step explanation:
The groove depth and contour of a recording medium are controlled by three factors: the rotation speed, the error correction mechanism, and the diffraction grating.
Firstly, the rotation speed of the medium is varied as the laser tracks toward the circumference to maintain a constant linear speed along the groove.
Secondly, the error correction mechanism is used to prevent the laser beam from getting off track.
Lastly, a diffraction grating creates maxima on either side of the track and any variation in their distance from the track indicates an error that needs to be corrected.