Curved Surface Roughness Measurement via Interferometry and Data Segmentation
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Solution Overview
Problem
Conventional methods face challenges in precisely measuring the surface height and roughness of curved objects, particularly cylindrical inner walls, due to manual analysis and reliability biases.
Innovation Solution
A method involving a measurement program that sets a measuring region and threshold values, acquires shape reference data, removes curvature data, calculates second reference data by averaging, and extracts concave and convex data to enable precise surface roughness calculation, using light interferometry for distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual analysis with laser microscope is used for cylindrical inner wall measurement, then measurement can be performed, but reliability bias and examiner bias increase
Solution Approach 1:
The patent replaces manual mechanical measurement methods with an automated optical measurement system. The light interferometry system automatically captures interference images and processes surface height data through computational algorithms, eliminating the need for manual operation with laser microscopes and thereby removing examiner bias while improving reliability.
Solution Approach 2:
The patent creates a digital copy of the physical surface through optical interferometry. By capturing interference patterns and converting them into surface height data, the system creates an accurate digital representation that can be analyzed automatically without manual intervention, thus improving both automation and reliability.
2Measurement precision
If conventional light interferometry is used for curved surface measurement, then surface height can be measured, but the curved shape contaminates the roughness measurement
Solution Approach 1:
The patent segments the surface data into two distinct components: the macroscopic curved shape and the microscopic surface roughness. By calculating reference data that represents the ideal curved surface and subtracting it from the measured surface height data, the system separates these two elements, allowing precise roughness measurement without contamination from the curved shape.
Solution Approach 2:
The patent extracts the curved shape component from the total surface height data by calculating reference data based on the curved surface geometry. This extracted reference data is then removed from the measured data, leaving only the roughness information that can be accurately analyzed without the confounding influence of the curved shape.
3Measurement precision
If threshold value filtering is applied to remove curve data, then roughness measurement improves, but concave and convex features may be removed
Solution Approach 1:
The patent segments the surface features into three categories: the macroscopic curved shape (removed through reference data subtraction), the microscopic roughness (measured from the remaining data), and the intermediate concave and convex features (identified and extracted through threshold filtering). This multi-level segmentation allows each feature type to be analyzed separately with appropriate methods.
Solution Approach 2:
Instead of removing concave and convex features as noise, the patent inverts the approach by using threshold filtering to identify and extract these features as valuable information. By setting appropriate thresholds, the system captures features that exceed normal roughness variations, preserving them as meaningful surface characteristics rather than eliminating them.
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 allows for automatic and precise measurement of curved surfaces, reducing reliance on manual analysis and improving measurement accuracy by isolating concave and convex features from the surface data.
Implementation Method 1
Light interferometry that uses brightness information of interference fringes occurring due to optical interference, has been known as a method of measuring the surface height, the surface roughness, and the three-dimensional shape of a measuring object.
Data Source
AI summary
According to an embodiment of the present invention, a method of measuring a surface of an object having a curved shape by measuring a distance from a measurement head to the object, includes: setting a measuring region of the object and a threshold value of concave and convex; acquiring shape reference data including the curved shape of the object; acquiring three-dimensional data of the surface of the object by measuring the distance between the object in the measuring region and the measurement head; acquiring curve removed data by removing the shape reference data from the three-dimensional data; calculating second reference data by calculating first reference data based on the curve removed data, by removing data exceeding the threshold value with respect to the first reference data, from the curve removed data, and by averaging the curve removed data; and calculating shape data of the concave and convex.