Patent ID: 8842507

Claim:
A heat-assisted magnetic recording (HAMR) disk drive comprising: a rotatable disk having a magnetic recording layer, the recording layer having a plurality of data tracks, each data track having a plurality of data regions and nondata regions; a write head comprising an electrically conductive coil and a write pole, the coil being adapted to generate write pulses to thereby cause the write pole to write data regions as the disk rotates; a carrier for supporting the write head, the carrier having a disk-facing surface; a laser; a near-field transducer (NFT) on the carrier and coupled to the laser for heating the data regions to facilitate writing of the data regions by the write pole as the disk rotates; a controller coupled to the write head for initiating writing to the data regions and to the laser for setting laser power levels, the laser power settings determining the heat generated by the NFT to the data regions during writing; an electrically conductive sensor on the carrier, the sensor being adapted to exhibit a change in electrical resistance in response to a change in temperature; electrical circuitry coupled to the sensor and for providing an output signal representative of a change in electrical resistance of the sensor; and a processor coupled to the controller and the sensor circuitry for computing a prediction of the laser power to be applied during writing a selected data region from a history of prior laser power settings corresponding to writing prior data regions, for computing a difference between said sensor circuitry output signal and said predicted laser power, and for generating a signal to the controller to adjust the laser power setting and initiate re-writing of said selected data region if the absolute value of said computed difference is greater than a predetermined threshold.