HAMR Head Laser Stability Calibration via Temperature Ramps

The patent applies local quality by adjusting only the specific HAMR heads that exhibit laser power variations (outlier heads) while leaving well-performing heads unchanged. This is achieved by individually testing each head's performance across temperature ramps and selectively adjusting only those heads that fall outside the normal performance range, thereby maintaining local optimization rather than uniform adjustment across all heads.

The patent applies parameter changes by adjusting the operating parameters (such as laser power, write current, or temperature compensation values) of identified outlier heads to compensate for their specific laser power variations. This selective parameter adjustment stabilizes write performance without applying excessive compensation that would reduce the safety margin and increase bit error rates.

The patent applies the taking out principle by extracting and identifying only the specific outlier heads with laser power variations from the population of all HAMR heads. Instead of deactivating all heads or the entire drive, the method isolates and adjusts only the problematic individual heads, preserving the functionality and storage capacity contributed by well-performing heads while addressing the reliability issues of the outliers.