Patent ID: 7480216

Claim:
An optical information recording apparatus which optically reads and writes information from and to a recording medium, comprising: a first detector for detecting amplitude of a readout signal; a second detector for detecting amplitude of a tracking error signal; a first adjustor for adjusting spherical aberration; a second adjustor for adjusting defocus of an objective lens; an oblique search means for changing the spherical aberration and the defocus obliquely in a two-dimensional rectangular coordinate system whose respective axes represent the defocus and the spherical aberration; a rectangular search means for changing the spherical aberration and the defocus rectangularly in the two-dimensional rectangular coordinate system; and a switching means for switching the oblique search means and the rectangular search means when adjusting coarsely and finely; wherein: the spherical aberration and the defocus are adjusted at first obliquely by the oblique search means so as to maximize the amplitude of the tracking error signal and then adjusted rectangularly by the rectangular search means so as to maximize the amplitude of the readout signal, the recording medium is a non-rotary recording medium, said apparatus further comprises a memory for storing optimum spherical aberration values and optimum defocus values which are respectively for four corners on the recording medium, and the optimum spherical aberration and defocus values for an information read/write position are calculated from the stored optimum values by interpolation based on ratios in terms of distances from the four corners.