Optical disk and method of tracking the same

Claim 1

A tracking method for an optical disk formed to have adjacent tracks in the form of grooves, each of said grooves having two slanted surfaces respectively disposed on opposite sidewalls of said groove, the depth of a first plurality of said groove which constitutes every other one of said grooves being varied at a frequency f and the depth of a second plurality of grooves which constitute the remaining grooves being substantially constant, said method comprising the steps of: irradiating two successive slanted surfaces of said optical disk with two independently driven focussed spots of light to perform one of a recording and reproducing operation independently on said two successive slanted surfaces, detecting the magnitude of respective frequency components from beams reflected from said two successive slanted surfaces corresponding to said two spots of light, and controlling the position of said two spots of light relative to said optical disk so that the magnitudes of the detected frequency components corresponding to said two spots of light are equal to each other.