Off-Disk NFT Protrusion Measurement in HAMR Transducers
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Solution Overview
Problem
Conventional methods for testing the protrusion of near-field transducers (NFTs) in heat-assisted magnetic recording (HAMR) disk drives are unreliable due to the challenges of accurately measuring deformation under operating conditions, particularly because existing methods require the NFT to be in proximity to a disk and are affected by cooling from the media, leading to potential contact and performance issues.
Innovation Solution
A method involving the use of an atomic force microscope (AFM) or other precise measurement tools to measure the protrusion of the NFT when the HAMR head is not in a disk drive, allowing for accurate determination of protrusion at various laser powers without the influence of cooling from the media, and accounting for deformation through baseline and operational location measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to measure NFT protrusion with the NFT in proximity to the disk, then the measurement can be performed under operating conditions, but the measurement precision deteriorates due to cooling from the media and potential contact issues
Solution Approach 1:
The patent extracts the NFT from its operating environment (proximity to the disk) and measures its protrusion in isolation using an AFM. This eliminates the interfering cooling effects and contact issues that occur when the NFT is near the disk, while still allowing prediction of operational deformation through baseline comparisons
Solution Approach 2:
The patent performs preliminary measurements of the NFT protrusion before the NFT is subjected to operating conditions (laser heating). By establishing a baseline measurement in a controlled environment, the system can later predict operational deformation by comparing post-operation measurements against this pre-established baseline
2Measurement precision
If the NFT is measured under operating conditions with laser heating, then the measurement reflects actual performance, but the measurement becomes unreliable due to thermal cycling and media cooling effects
Solution Approach 1:
The patent introduces an AFM as an intermediary measurement tool that can accurately measure NFT protrusion without being affected by the harsh operating conditions. The AFM provides a stable measurement platform that isolates the measurement process from thermal cycling and media cooling effects, enabling reliable measurements that still reflect operational deformation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables more accurate and reliable measurement of NFT protrusion, predicting deformation under operating conditions and improving the performance and reliability of HAMR disk drives by providing precise data for design and material property calibration.
Implementation Method 1
A method involving the use of an atomic force microscope (AFM) or other precise measurement tools to measure the protrusion of the NFT
Implementation Method 2
The laser is energized with a particular power... allowing for accurate determination of protrusion at various laser powers
Implementation Method 3
predicting deformation under operating conditions
Implementation Method 4
measure the protrusion of the NFT when the HAMR head is not in a disk drive, allowing for accurate determination of protrusion
Data Source
AI summary
A method and system test a heat assisted magnetic recording (HAMR) transducer. The HAMR transducer is optically coupled to at least one laser and has an air-bearing surface. The HAMR transducer includes at least one waveguide, at least one near-field transducer (NFT) and a pole. A portion of the NFT(s) resides at the ABS. The laser(s) are optically coupled to the NFT(s). The method and system include energizing the laser(s) at power(s) while the HAMR transducer is not in proximity to a media. The method and system also include measuring an off-disk protrusion of the portion of the NFT(s) at the ABS while the laser(s) are energized and the HAMR transducer is not in proximity to the media.