Patent ID: 8169863

Claim:
A tracking control device which performs control so as to cause a convergence point of a main beam to scan a track on a prescribed information layer of an information recording medium having a plurality of information layers, based on a differential push-pull signal obtained by subtracting (i) a sub-push-pull signal generated from return light of a sub-beam reflected from the prescribed information layer from (ii) a main push-pull signal generated from return light of the main beam reflected from the prescribed information layer, the tracking control device comprising: a main push-pull signal generation section which generates the main push-pull signal based on a signal obtained by photoelectric conversion of the return light of the main beam; an other-layer stray light calculation section which (i) obtains the signal obtained by photoelectric conversion of the return light of the main beam, (ii) calculates a light quantity ratio of a light quantity of the return light of the main beam to a light quantity of other-layer stray light, and (iii) multiplies the calculated light quantity ratio by the signal obtained by the photoelectric conversion of the return light of the main beam to calculate an other-layer stray light signal component that is (i) included in a signal obtained by photoelectric conversion of the return light of the sub-beam and (ii) equivalent to other-layer stray light reflected from an information layer different from the information layer on which the main beam is converged; a signal correction section which corrects the signal obtained by photoelectric conversion of the return light of the sub-beam, based on the other-layer stray light signal component calculated by the other-layer stray light calculation section; and a sub-push-pull signal generation section which generates the sub-push-pull signal based on the signal obtained by photoelectric conversion of the return light of the sub-beam, corrected by the signal correction section.