Dual Bolometric Sensor for HAMR Laser Monitoring
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Solution Overview
Problem
In heat-assisted magnetic recording (HAMR) devices, conventional sensors struggle to accurately detect head-to-medium spacing and contact while monitoring laser power without compromising light delivery or requiring additional bond pads, leading to potential data errors due to mode hopping and increased complexity.
Innovation Solution
A dual-function bolometric sensor is positioned adjacent to the near-field transducer, capable of detecting changes in head-to-medium spacing and contact, as well as fluctuations in laser output power, by absorbing waste light and using a high thermal coefficient of resistance material, thus eliminating the need for additional bond pads and maintaining light path efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensors are used to detect head-to-medium spacing and contact, then measurement function is provided, but additional bond pads are required and light delivery is compromised
Solution Approach 1:
The patent combines the laser power monitoring function and head-to-medium spacing detection function into a single bolometric sensor. The sensor is positioned to simultaneously receive light from the laser source and detect thermal changes caused by head-medium contact, eliminating the need for separate sensors and their associated bond pads.
Solution Approach 2:
The bolometric sensor serves multiple functions: it acts as both a laser power monitor and a head-to-medium spacing sensor. By utilizing the same sensor element for both measurement tasks, the design reduces device complexity while maintaining measurement capabilities.
2Measurement precision
If conventional sensors are used to monitor laser power, then power detection is achieved, but light delivery efficiency is reduced
Solution Approach 1:
The bolometric sensor acts as an intermediary that indirectly measures laser power through thermal detection rather than directly intercepting the light path. The sensor detects power fluctuations by measuring thermal changes in the slider body caused by absorbed laser energy, allowing power monitoring without significant light loss.
Solution Approach 2:
The patent replaces direct optical measurement with thermal detection. Instead of using an optical sensor that would intercept light, the system uses a bolometric sensor that detects power through thermal effects, substituting a thermal measurement mechanism for an optical one.
3Measurement precision
If separate sensors are used for spacing detection and laser power monitoring, then measurement accuracy is maintained, but device complexity increases
Solution Approach 1:
The patent merges two separate sensing functions into a single integrated bolometric sensor. The sensor is positioned and configured to simultaneously perform laser power monitoring and head-to-medium spacing detection, reducing the number of components while maintaining both measurement functions.
Solution Approach 2:
The bolometric sensor is designed as a multi-functional device that can perform both laser power monitoring and spacing detection. This universal sensor approach simplifies the overall device architecture while preserving the measurement capabilities of both functions.
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 bolometric sensor effectively monitors head-medium interactions and laser power fluctuations, preventing data errors and reducing complexity by integrating both functions into a single device with minimal impact on the near-field transducer's performance.
Implementation Method 1
A bolometric sensor is positioned proximate the NFT and exposed to at least some of the light
Implementation Method 2
The bolometric sensor is configured to detect changes in output optical power of the laser source
Implementation Method 3
using a high thermal coefficient of resistance material
Implementation Method 4
A near-field transducer (NFT) is formed on the slider at or near an air bearing surface (ABS) of the slider and optically coupled to the waveguide
Data Source
AI summary
An apparatus comprises a slider and an optical waveguide formed in the slider and configured to receive light from a laser source. A near-field transducer (NFT) is formed on the slider at or near an air bearing surface (ABS) of the slider and optically coupled to the waveguide. A bolometric sensor is positioned proximate the NFT and exposed to at least some of the light. The bolometric sensor is configured to detect changes in output optical power of the laser source and contact between the slider and a magnetic recording medium.