Patent ID: 6278667
Filing Date: 2001-08-21
Classification: G11B

Abstract:
A method of controlling laser power in a magneto-optical storage system having a rotating magneto-optical medium onto which information is written and read using the laser, the method comprising directing laser light onto a pattern on the magneto-optical medium;receiving laser light reflected from the medium;generating from the received light a signal representative of a characteristic of the reflected light;controlling the power of the laser to cause the signal to assume a predetermined value, wherein the pattern comprises a pattern of alternating evenly spaced magnetizations defining a tone having a predetermined frequency, wherein the magnetizations have a predetermined in-track spacing, wherein the signal representative of a characteristic of the reflective light comprises a signal corresponding to an amplitude of detected polarization values in the reflected light, wherein the amplitude of the signal corresponds to the temperature of the magneto-optical medium, wherein the controlling the power comprises controlling the power of the laser to provide a predetermined temperature, wherein the temperature of the medium is related to the size of a read aperture in the medium, wherein the controlling the power comprises controlling read aperture size, wherein the controlling the power comprises controlling the power of the laser to provide a read aperture size which is less than the spacing between adjacent magnetic regions in the magneto-optical medium containing the pattern, and wherein the patterns comprise prerecorded tones of different spatial frequency;measuring the amplitude of the received light signals for a plurality of different laser powers;defining a functional relationship between amplitude and laser power from the measured values; andcontrolling the power of the laser using the functional relationship to provide a predetermined aperture size.