Patent ID: 6920099

Claim:
An optical disk recording and reproducing apparatus being operative in a read mode for controlling a laser driver to maintain a laser power at a target read level so as to read a signal from an optical disk, and being operative in a write mode for controlling the laser driver to alternate the laser power between a target write level and a target bottom level comparative with the target read level so as to write a signal at a constant density into the optical disk which is rotated at a constant angular velocity, the apparatus comprising: a first detector being operative in the read mode for detecting a read level of the laser power, and being operative in the write mode for detecting a bottom level of the laser power; a first controller being operative in the read mode for outputting a read level control signal according to a difference between the detected read level and the target read level, and being operative in the write mode for outputting a bottom level control signal according to a difference between the detected bottom level and the target bottom level; a second detector operative in the write mode for detecting a write level of the laser power; a second controller operative in the write mode for outputting a write level control signal according to a difference between the detected write level and the target write level; and a third controller being operative in the read mode for providing the read level control signal to the laser driver, and being operative in the write mode for alternately providing the write level control signal and the bottom level control signal to the laser driver in accordance with the signal to be written into the optical disk, wherein the first controller operates in a pre-write mode prior to the write mode for performing a writing operation at different linear velocities along the optical disk to sample at least first and second bottom levels of the laser power, and operates in the write mode for monitoring a linear velocity at a point of the optical disk where the signal is to be recorded and for calculating a target bottom level at the monitored linear velocity by interpolation of the sampled first and second bottom levels, thereby outputting the bottom level control signal according to a difference between the calculated target bottom level and the detected bottom level of the laser power.