Measuring NFT protrusion in a heat assisted magnetic recording drive using burst writing and a constant laser diode temperature

A method of operating a data storage device utilizing heat assisted magnetic recording (HAMR), the method comprising:

• preheating a first laser diode (LD) to a steady state temperature, wherein the first LD is associated with a first head of the data storage device, the first head comprises a near field transducer (NFT);
• after the preheating,
• writing, using the first head, a first series of writings at a plurality of thermal fly-height control (TFC) powers;
• writing, using the first head, a second series of writings at the plurality of TFC powers, wherein the first series of writings are of a shorter duration than the second series of writings;
• and
• determining, for the first head, an NFT protrusion measurement based at least on a difference in TFC power used between (1) one of the first of writings and (2) one of the second series of writings, at a corresponding written signal amplitude.

One or more processing devices or components, comprising:

• means for preheating a first laser diode (LD) of a data storage device to a steady state temperature, wherein the first LD is associated with a first head of the data storage device, and wherein the data storage device is configured for heat assisted magnetic recording (HAMR);
• after the preheating,
• means for writing, using the first head, a first series of writings at a plurality of thermal fly-height control (TFC) powers;
• means for writing, using the first head, a second series of writings at the plurality of TFC powers, wherein the first series of writings have a shorter duration than the second series of writings;
• and
• means for determining, for the first head, an NFT protrusion measurement based at least on a difference in TFC power used between (1) one of the first of writings and (2) one of the second series of writings, at a corresponding written signal amplitude.