Patent ID: 8054725

Claim:
An optical disk apparatus for writing signals on a recording medium by irradiating the recording medium with a laser beam modulated based on the signals, comprising: first converting means for Converting a first reflected laser beam component obtained by irradiating the recording medium with the laser beam into electrical signals; second converting means for converting a part of a second reflected laser beam component into electrical signals; first sample-and-hold means for sampling and holding the electrical signals obtained by the first converting means, the first sample-and-hold means comprising: a first sample-and-hold circuit for a write mode for sampling and averaging the electrical signals, and for holding the averaged signal while the laser beam is emitted at a write laser power, and a second sample-and-hold circuit for a bias mode for sampling and holding the electrical signals while the laser beam is emitted at a bias laser power; second sample-and-hold means for sampling and holding the electrical signals obtained by the second converting means, the second sample-and-hold means comprising: a third sample-and-hold circuit for the write mode for sampling and averaging the electrical signals, and for holding the averaged signal while the laser beam is emitted at the write laser power, and a fourth sample-and-hold circuit for the bias mode for sampling and holding the electrical signals while the laser beam is emitted at the bias laser power; and transmitting means for transmitting the held signals obtained by the first and the second sample-and-hold means to signal-processing means at the next stage.