Patent ID: 9741378
Date: 2017-08-22
CPC Classifications: G11B

Claim:
1. A method, comprising: moving a heat-assisted magnetic recording head relative to a magnetic recording medium comprising a plurality of tracks, the head comprising a reader and a writer including a near-field transducer (NFT) optically coupled to a laser diode, the writer comprising a center which is laterally offset relative to a center of the reader to define a writer-reader offset (WRO) therebetween; writing patterns to a particular track at a plurality of laser diode current levels; reading the patterns and calculating an WRO value at a peak amplitude position for each of the laser diode current levels; calculating a slope of the WRO values with the laser diode current levels; and determining a health condition of the NFT by determining if the slope is greater than a predetermined threshold indicative of non-uniform activation across the NFT.