PURPOSE: To make long time recording and reproducing possible by making recording or reproducing of information signals switching irradiation wavelength of the variable wavelength semiconductor laser of an optical head successively according to detection signals from a detector corresponding to a mark that indicates the position of starting end of rotation of an optical disk.
CONSTITUTION: A detector 15 detects that an optical disk 1 made one rotation by a rotation starting end position mark 3, and inputs a detection signal 16 to a controlling circuit 46. At this time, the controlling circuit 46 controls so as to make wavelength λ2 different from irradiation wavelength λ1 from a semiconductor laser 22 recorded in the optical disk 1 by previous one rotation becomes irradiation wavelength, and in the next one rotation, irradiation wavelength from the semiconductor laser 22 becomes λ2, and recording is made on the same track by irradiation wavelength λ2. Every time the rotation starting end position mark 3 of the optical disk 1 is detected by the detector 15, irradiation wavelength (λ3...λn) is controlled so as to change successively by the controlling circuit 46, and thereby, only the irradiation wavelength (n sets of λ1, λ2, λ3...λn) from the semiconductor laser 22 can be recorded.
INOUE MASAYUKI
KISHI YUJI
FURUYA JUN
