Reflective Surface Slope Measurement via Digital Image Correlation
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Solution Overview
Problem
Existing methods for determining the geometric characteristics of reflective surfaces, such as surface slopes and curvatures, often require special conditions, destructive testing, or contact with the structure, limiting their applicability and accuracy.
Innovation Solution
A system and method using a camera and digital image correlation to capture and analyze images of reflective surfaces with feature points, determining surface slopes, curvatures, and topography without the need for coatings or destructive testing, by comparing displacements in captured images relative to reference images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical metrology tools such as shearing interferometry and moiré-based methods are used to quantify surface slopes and curvatures, then measurement capability is improved, but the method requires special conditions, destructive or contact testing, coatings, or grid patterns which increases device complexity and limits applicability
Solution Approach 1:
The invention extracts and removes the requirement for special coatings, grid patterns, and complex optical setups from the measurement process. By using a camera to directly capture images of the reflective surface with embedded features, the method eliminates the need for Ronchi rulings, monochromatic coherent light, and metallic film coatings that were required by traditional methods.
Solution Approach 2:
The invention creates a digital copy of the surface geometry through image capture and processing. Instead of requiring physical contact or special optical paths, the system captures images of the reflective surface and uses digital image correlation algorithms to extract slope and curvature information from the displaced feature points in the captured images.
2Measurement precision
If traditional optical methods are employed to determine surface geometry, then measurement accuracy is improved, but the methods require contact testing or coating the structure which causes damage to the specimen
Solution Approach 1:
The reflective surface itself serves as the measurement target. The embedded features on the reflective surface reflect light back to the camera, and the displacement of these reflected features directly provides the measurement information. The surface serves both as the object being measured and as the carrier of measurement information, eliminating the need for external coatings or contact probes that could damage it.
Solution Approach 2:
The embedded features on the reflective surface act as intermediaries that carry geometric information. These features reflect light in a way that encodes the surface slope and curvature, allowing the camera to capture geometric information without physically contacting or coating the underlying structure.
3Object-affected harmful factors
If a camera captures images of reflected feature points and digital image correlation is applied to determine surface slopes, then non-destructive measurement is achieved, but the system requires precise positioning and optical alignment which increases device complexity
Solution Approach 1:
The invention transitions from traditional optical path measurements to two-dimensional image plane measurements. By capturing the reflected features on a 2D camera sensor and analyzing their displacements in the image plane, the system determines three-dimensional surface geometry without requiring precise control of the optical path geometry or component alignment.
Solution Approach 2:
The invention replaces complex mechanical alignment and positioning systems with computational image processing. Instead of requiring precise mechanical positioning of optical components and the specimen, the system uses digital image correlation algorithms to extract geometric information from the captured images, substituting mechanical precision requirements with computational analysis.
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 non-destructive, accurate determination of geometric characteristics of reflective surfaces under various loads, allowing for continuous monitoring without damaging the specimen, and providing detailed slope and curvature data.
Implementation Method 1
The reflective surface may be configured to reflect light of one or more wavelengths from the target structure to the camera
Data Source
AI summary
Illustrative embodiments of determining geometric characteristics of reflective surfaces are disclosed. In at least one illustrative embodiment, a method of determining geometric characteristics of reflective surfaces includes sensing electromagnetic waves with a sensor, where the electromagnetic waves have been reflected off a reflective surface of a specimen from a target structure including a feature point. The method further includes determining a displacement of the feature point of the target structure indicated by the sensed electromagnetic waves relative to reference data indicating a reference location for the feature point and determining a surface slope of a point of the reflective surface based on the determined displacement of the feature point of the target structure.