Data storage device predicting failure of near field transducer based on slope of thermal gradient
A data storage device is disclosed comprising a head actuated over a magnetic media, wherein the head comprises a laser and a near field transducer (NFT). A thermal gradient produced in the magnetic media by the NFT is periodically measured, and a failure of the NFT is predicted based on a slope of the thermal gradient measurements.
1. A data storage device comprising:
a magnetic media;
a head actuated over the magnetic media, wherein the head comprises a laser and a near field transducer (NFT); and
control circuitry configured to:
periodically measure a thermal gradient produced in the magnetic media by the NFT;
predict a failure of the NFT based on a slope of the thermal gradient measurements; and
measure the thermal gradient by measuring a cross-track thermal gradient.
2. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to predict the failure of the NFT when an absolute value of the slope exceeds a threshold.
3. The data storage device as recited in claim 2 , wherein the control circuitry is further configured to predict the failure of the NFT when the slope is negative.
4. The data storage device as recited in claim 1 , wherein the control circuitry is further configured to:
calibrate a control signal applied to the laser in order to achieve a target areal density of the magnetic media;
periodically adjust the control signal to maintain a target quality metric; and
after adjusting the control signal at least once, measure the thermal gradient.
5. A data storage device comprising:
a magnetic media;
a head actuated over the magnetic media, wherein the head comprises a laser and a near field transducer (NFT); and
control circuitry configured to:
periodically measure a parameter for the NFT;
predict a failure of the NFT based on a slope of the parameter measurements;
calibrate a control signal applied to the laser in order to achieve a target areal density of the magnetic media;
periodically adjust the control signal to maintain a target quality metric; and
after adjusting the control signal at least once, measure the parameter for the NFT.
6. The data storage device as recited in claim 5 , wherein the measured parameter for the NFT comprises a thermal gradient produced in the magnetic media.
7. The data storage device as recited in claim 5 , wherein the control circuitry is further configured to predict the failure of the NFT when an absolute value of the slope exceeds a threshold.
8. The data storage device as recited in claim 7 , wherein the control circuitry is further configured to predict the failure of the NFT when the slope is negative.
9. The data storage device as recited in claim 6 , wherein the control circuitry is further configured to measure the thermal gradient by measuring a cross-track thermal gradient.
10. The data storage device as recited in claim 6 , wherein the control circuitry is further configured to measure the thermal gradient by measuring a down-track thermal gradient.
11. A data storage device comprising:
a magnetic media;
a head actuated over the magnetic media, wherein the head comprises a laser and a near field transducer (NFT); and
a means for periodically measuring a parameter for the NFT; and
a means for predicting a failure of the NFT based on a slope of the parameter measurements, wherein the failure of the NFT is predicted when an absolute value of the slope exceeds a threshold.
12. The data storage device as recited in claim 11 , wherein the measured parameter for the NFT comprises a thermal gradient produced in the magnetic media.
13. The data storage device as recited in claim 11 , wherein the failure of the NFT is predicted when the slope is negative.
14. The data storage device as recited in claim 11 , further comprising:
a means for calibrating a control signal applied to the laser in order to achieve a target areal density of the magnetic media;
a means for periodically adjusting the control signal to maintain a target quality metric; and
after adjusting the control signal at least once, a means for measuring the parameter for the NFT.
15. The data storage device as recited in claim 12 , wherein the thermal gradient is measured by measuring a cross-track thermal gradient.
16. The data storage device as recited in claim 12 , wherein the thermal gradient is measured by measuring a down-track thermal gradient.
17. A data storage device comprising:
a magnetic media;
a head actuated over the magnetic media, wherein the head comprises a laser and a near field transducer (NFT); and
control circuitry configured to:
periodically measure a thermal gradient produced in the magnetic media by the NFT;
predict a failure of the NFT based on a slope of the thermal gradient measurements; and
measure the thermal gradient by measuring a down-track thermal gradient.