Optical Fly Height Measurement Using Planar Waveguide Diffraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Accurately measuring small distances, such as nanoscale fly height between a slider and a disc in data storage systems, is challenging due to the decreasing dimensions required for increased storage density, necessitating a precise method to ensure proper system operation.
Innovation Solution
A fly height measurement system utilizing a planar waveguide with diffraction gratings to direct and receive electromagnetic waves, allowing for the determination of the distance between the slider's air bearing surface and the disc by analyzing the intensity of reflected light, which is affected by the fly height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the fly height is reduced to increase storage density, then the areal density is improved, but the measurement precision deteriorates due to the nanoscale dimensions becoming difficult to measure
Solution Approach 1:
The patent replaces conventional mechanical or direct physical measurement methods with an optical measurement system. A light source emits light that reflects off the air bearing surface, and the reflected light is detected to determine fly height. This optical substitution enables precise measurement of nanoscale distances that are otherwise difficult to measure with traditional mechanical gauges or sensors.
Solution Approach 2:
The patent utilizes changes in optical parameters (light intensity, phase, or interference patterns) as the fly height changes. By monitoring how the reflected light properties vary with distance, the system can precisely measure nanoscale fly height variations. The measurement system detects parameter changes in the light field that correspond to minute changes in the slider-to-disc distance.
2Measurement precision
If conventional measurement methods are used, then the device complexity is low, but the measurement precision deteriorates at nanoscale dimensions
Solution Approach 1:
The patent introduces light as an intermediary medium between the measurement system and the air bearing surface. Instead of directly measuring the physical distance with mechanical contact, the system uses light reflection as an intermediary process. The light carries information about the fly height from the inaccessible nanoscale gap to the detector, enabling indirect but precise measurement.
Solution Approach 2:
The patent replaces complex mechanical measurement apparatus with a relatively simple optical system consisting of a light source, reflective surface, and detector. This substitution reduces mechanical complexity while enabling nanoscale measurement capability that mechanical systems cannot achieve.
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
Enables accurate measurement of fly height, ensuring optimal data storage system performance and maintaining high areal density by precisely determining the distance between the slider and disc, even at nanoscale dimensions.
Implementation Method 1
a first diffraction grating for coupling an electromagnetic wave into the planar waveguide
Implementation Method 2
The waveguide has a core layer spaced from the disc by a distance corresponding to a fly height of the air bearing surface
Implementation Method 3
a second diffraction grating for receiving the electromagnetic wave reflected from the air bearing surface
Data Source
AI summary
An optical fly height measurement system includes a planar waveguide, a first diffraction grating for coupling an electromagnetic wave into the planar waveguide wherein the first diffraction grating is positioned for directing the electromagnetic wave towards an air bearing surface of a slider. A second diffraction grating is provided for receiving the electromagnetic wave reflected from the air bearing surface. A detector module and processor are provided to determine the fly height.