Laser adjustment during field operation of a heat-assisted magnetic recording data storage device
AssigneeSeagate Technology LLC
InventorsAlfredo Sam Chu, Drew Michael Mader, Wenzhong Zhu, Michael A. Cordle
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Abstract
During field operation of a heat-assisted magnetic recording data storage device, a laser adjustment procedure is performed. The laser adjustment procedure involves writing on a recording medium at least three tracks. If a bit error rate of a middle tracks has increased, the laser current is swept while recording test tracks to determine a new laser current that results in a minimum bit error rate. The new laser current is used for subsequent write operations.
Claims20
A method, comprising:
- energizing a near-field transducer with a laser during field operation of a heat-assisted magnetic recording data storage device;
- detecting an event during the field operation that indicates a possible change in the near-field transducer performance;
- in response to the event, performing a laser adjustment procedure comprising:
- writing, via the near-field transducer on a recording medium of the data storage device, at least three test tracks;
- in response to determining an increase in bit-error-rate of a middle track of the at least three test tracks, sweeping the laser current while recording additional test tracks to determine a new laser current that results in a target bit error rate;
- and
- using the new laser current for subsequent write operations.
The method of claim I, wherein sweeping the laser current while recording the additional test tracks comprises increasing the laser current during a first series of sweeps to find a first minimum bit error rate, and then decreasing the laser current during a second series of sweeps to determine whether a second bit error rate is found lower than the first minimum bit error rate, the target bit error rate being selected from the first and second minimum bit error rates.
A method, comprising:
- during field operation of a heat-assisted magnetic recording data storage device, determining a change in a bias current used to maintain a predefined operational point of a laser that energizes a near-field transducer;
- and
- in response to determining the change in the bias current, performing a calibration of the laser comprising:
- writing on a recording medium of the data storage device via the laser, at least three test tracks;
- and
- in response to determining an increase in a bit error rate of a middle track of the at least three test tracks, sweeping the laser current while recording additional test tracks to determine a new laser current that results in a target bit error rate, and using the new laser current for subsequent write operations.
An apparatus, comprising:
- a preamplifier section configured to communicate with a read/write head of a heat-assisted magnetic recording data storage device, the read/write head comprising a laser that energizes a near-field transducer;
- and
- a controller configured to, during field operation of the apparatus:
- detect an event during field operation of a heat-assisted magnetic recording data storage device that indicates at least one of:
- a possible change in performance of the near-field transducer;
- and a change in a bias current used to maintain a predefined operational point of the laser;
- in response to the event, write at least three test tracks using the read/write head;
- and
- in response to determining an increase in bit-error-rate of a middle track of the at least three test tracks, sweep the laser current while recording additional test tracks to determine a new laser current that results in a target bit error rate, the new laser current being used for subsequent write operations.
Dependencies are inferred from the claim text.