Method and apparatus for determining power level of laser beam in magneto-optical recording device

A method for reproducing a signal from a magneto-optical recording medium by using laser light and alternating magnetic field, including:

• a first step of recording a predetermined record signal to said magneto-optical recording medium;
• a second step of reproducing said signal recorded in said first step while changing a power level of laser light;
• a third step of comparing a signal reproduced in said second step with said record signal and determining a power level of laser light at which said reproduced signal is substantially coincident with said record signal;
• and
• a fourth step of reproducing a signal from said magneto-optical recording medium by using laser light set in said power level determined in said third step and alternating magnetic field.

A method of reproducing a signal from a magneto-optical recording medium by using a laser light and alternating magnetic field, including:

• a first step of recording a predetermined record signal in a calibration region provided in said magneto-optical recording medium;
• a second step of reproducing said record signal from said calibration region while changing a power level of laser light, by using laser light and alternating magnetic field;
• a third step of comparing a signal reproduced in said second step with said record signal and determining a power level of laser light at which said reproduced signal is substantially coincident with said record signal;
• and
• a fourth step of reproducing a signal from said magneto-optical recording medium by using laser light set in said power level determined in said third step and alternating magnetic field.

A magneto-optical disk apparatus for recording and/or reproducing to and/or from a magneto-optical recording medium by using laser light and magnetic field, comprising;

• an optical head for illuminating laser light to said magneto-optical recording medium and detecting reflection light thereof;
• a laser drive circuit for driving a laser light source included in said optical head;
• a magnetic head for applying magnetic field to said magneto-optical recording medium;
• and
• a determination circuit for outputting a drive signal to said laser drive circuit to change a power level of laser light to be emitted through said optical head, and determining a power level of laser light based on a predetermined record signal recorded to said magneto-optical recording medium, and on a signal reproduced of said record signal detected by laser light emitted from said optical head based on said drive signal and alternating magnetic field applied from said magnetic head, so that said reproduced signal becomes substantially coincident with said record signal.

A magneto-optical disk apparatus for recording and/or reproducing a signal to and/or from a magneto-optical recording medium by using laser light and magnetic field, comprising;

• an optical head for illuminating laser light to said magneto-optical recording medium and detecting reflection light thereof;
• a laser drive circuit for driving laser light source included in said optical head;
• a magnetic head for applying magnetic field to said magneto-optical recording medium;
• a magnetic head drive circuit for driving said magnetic head;
• and
• a determination circuit for outputting to said magnetic head drive circuit a first drive signal to record a predetermined record signal in said magneto-optical recording medium and to said laser drive circuit a second drive signal to change a power level of laser light to be emitted through said optical head, and determining a power level of laser light based on a predetermined record signal recorded based on said first drive signal, and signal reproduced of said record signal detected by laser light emitted from said optical head based on said second drive circuit and alternating magnetic field applied from said magnetic head, so that said reproduced signal becomes substantially coincident with said record signal.