Magnetooptical recording reproducing apparatus and method for determining the power of an irradiating light beam on the basis of a detected amplitude of a recording signal

A magnetooptical recording/reproducing apparatus comprising:

• a light source for emitting a light beam;
• an optical system for irradiating a magnetooptical recording medium with the light beam emitted from said light source;
• a magnetic head for recording information signals on the recording medium by applying a magnetic field, modulated in accordance with a signal to be recorded, to a portion of the recording medium, irradiated by the light beam;
• a photodetector for detecting light, reflected by the medium, and for producing an output;
• a signal processing circuit for reading out from the output of said photodetector a magnetooptical signal during a recording operation;
• and
• a controller for determining the power of the light beam on the basis of an amplitude of the magnetooptical signal read out by said signal processing circuit.

A method for determining the power of a light beam in a magnetooptical recording/reproducing apparatus for effecting at least one of information recording and reproduction by irradiating a magnetooptical recording medium with a light beam, said method comprising the steps of:

• irradiating the medium with a light beam having a constant power;
• applying, simultaneously with the irradiation of the medium with the light beam, a magnetic field, modulated in accordance with a signal to be recorded, to a portion of the medium, irradiated with the light beam to record a signal on the medium;
• detecting, simultaneously with said irradiation of the light beam, light reflected by the medium;
• reading out a magnetooptical signal from the reflected light detected in said detecting step;
• and
• determining the power of the light beam so that an amplitude of the read out magnetooptical signal falls within a predetermined range.

A method for determining the power of a light beam, in a magnetooptical recording/reproducing apparatus for effecting at least one of information recording and reproduction by irradiating a magnetooptical recording medium with the light beam, said method comprising the steps of:

• recording pits having a predetermined pattern on the medium;
• irradiating a portion of the medium on which the pits are recorded with a light beam having a constant power;
• applying, simultaneously with the irradiation of the medium with the light beam, a magnetic field having a constant direction to a portion of the medium, irradiated with the light beam to record a signal on the medium;
• detecting, simultaneously with the irradiation of the medium with the light beam, light reflected by the medium;
• reproducing a signal of the pits from the detected reflected light;
• and
• determining the power of the light beam, based on an amplitude of the reproduced signal.

A method for determining the power of a light beam, in a magnetooptical recording/reproducing apparatus for effecting at least one of information recording and reproduction by irradiating a magnetooptical recording medium with the light beam, said method comprising the steps of:

• irradiating the medium with a light beam having a constant power;
• applying, simultaneously with the irradiation of the medium with the light beam, a magnetic field, modulated in accordance with a signal to be recorded, to a portion of the medium, irradiated by the light beam, thereby recording a first signal on the medium;
• re-irradiating the portion of the medium on which the first signal is recorded with a light beam having a constant power;
• applying, simultaneously with the re-irradiation of the light beam, a magnetic field, modulated in accordance with a second signal to be recorded, to a portion of the medium, irradiated with the light beam, thereby overwriting the second signal on the portion of the medium on which the first signal has been recorded;
• detecting, simultaneously with the re-irradiation of the light beam, light reflected by the medium;
• reproducing the first signal from the detected reflected light;
• and
• determining the power of the light beam, based on an amplitude of the reproduced first signal.