Far-Field Optical Testing for HAMR Slider Characterization
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Solution Overview
Problem
Existing metrology setups for heat-assisted magnetic recording (HAMR) sliders face reliability issues and inefficiencies due to contact-based laser coupling, which can damage equipment and complicate alignment, leading to reduced throughput and inaccurate testing of slider optics during manufacturing.
Innovation Solution
A far-field optical testing system using a production-type laser with far-field light illumination and collection optics to characterize HAMR sliders nondestructively, measuring depolarization, coupling efficiency, and reflection spectra, allowing for quick and accurate assessment of slider performance without physical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact-based laser coupling is used for HAMR slider testing, then alignment precision can be achieved, but equipment damage and operational complexity increase
Solution Approach 1:
The patent introduces a far-field optical system as an intermediary between the laser source and the HAMR slider. Instead of direct contact coupling, the system uses optical far-field illumination to indirectly couple light into the slider's waveguide, eliminating mechanical contact and associated damage risks while maintaining coupling precision through optical field matching
Solution Approach 2:
The patent replaces the mechanical contact-based laser coupling system with an optical far-field illumination system. This substitution eliminates the need for physical contact and mechanical alignment adjustments, reducing equipment damage while maintaining measurement precision through non-contact optical coupling
2Measurement precision
If contact-based laser coupling is used for HAMR slider testing, then coupling efficiency can be measured, but operational complexity and alignment time increase
Solution Approach 1:
The patent implements preliminary alignment through automated optical field matching in the far-field configuration. The system pre-characterizes the optical modes and coupling conditions before actual measurement, allowing rapid subsequent measurements without repeated complex alignment procedures, thus improving processing speed while maintaining measurement accuracy
Solution Approach 2:
The patent replaces manual mechanical alignment procedures with automated optical field matching in the far-field configuration. This substitution eliminates time-consuming mechanical adjustments while maintaining coupling efficiency measurement accuracy through automated optical characterization
3Reliability
If far-field optical testing is implemented, then equipment damage is reduced, but system complexity increases
Solution Approach 1:
The patent implements a universal far-field optical testing platform that can characterize multiple HAMR slider parameters (coupling efficiency, optical mode matching, waveguide performance) using a single integrated system. This multi-functionality justifies the increased optical system complexity by eliminating the need for multiple separate testing apparatus and providing comprehensive slider characterization
4Productivity
If far-field optical testing is implemented, then processing speed increases, but measurement complexity increases
Solution Approach 1:
The patent implements automated feedback control in the far-field optical system, where measured optical parameters are fed back to adjust coupling conditions and optimize measurements in real-time. This automation reduces the perceived measurement complexity by eliminating manual intervention while maintaining high processing speed through rapid iterative optimization
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
The system enables reliable and efficient characterization of HAMR sliders, reducing downtime and increasing processing speed, providing meaningful statistics on slider performance and identifying defects, thus improving manufacturing quality and efficiency.
Implementation Method 1
A far-field light illumination path delivers excitation light from the production-type laser to the optical path of the HAMR slider. The excitation light is emitted from an air bearing surface (ABS) of the HAMR slider.
Implementation Method 2
Collection optics receive the emitted light from the ABS and distribute the emitted light to one or more sensors. A processor is coupled to the production-type laser and the one or more sensors.
Implementation Method 3
The processor is configured to determine, based on signals received from the one or more sensors, a depolarization of the emitted light and a coupling efficiency of the HAMR slider.
Implementation Method 4
A light source that emits light at a plurality of wavelengths over a spectral range. A far-field light illumination path delivers the light to an optical path of a heat-assisted magnetic recording (HAMR) slider, causing reflected light to be emitted from the HAMR slider towards the far field illumination path.
Implementation Method 5
A processor is coupled to the light source and the detector, and is operable to: determine a spectra of the reflected light based on the signal from the detector; perform a Fourier transform on the spectra of the reflected light to produce a reflection spectra; and determine locations of reflections within the optical path based on the reflection spectra.
Data Source
AI summary
A testing system includes a production-type laser having optical modes of a production laser that interfaces with an optical path of a heat-assisted magnetic recording (HAMR) slider. A far-field light illumination path delivers excitation light from the production-type laser to the optical path of the HAMR slider, the excitation light being emitted from an air bearing surface (ABS) of the HAMR slider. Optics receive the emitted light from the ABS and distribute the emitted light to one or more sensors. The system determines, based on signals received from the one or more sensors, a depolarization of the emitted light and a coupling efficiency of the HAMR slider. The system may also measure light reflecting out of the optical path and Fourier transform these measurements to determine locations of reflections within the optical path.