Micrometre Surface 3D Reconstruction Using LED Fringe Projection
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Solution Overview
Problem
Existing three-dimensional object reconstruction systems by laser triangulation struggle to achieve micrometric resolution for millimetric objects, limiting their ability to accurately measure surface characteristics such as crack depth, hollows, and roughness.
Innovation Solution
A surface acquisition system using an LED to project a fine light beam with a fringe thickness of less than 50 μm, combined with dual cameras to reduce blind spots and sub-pixel profile analysis to correct noise, enabling micrometric resolution and depth field for precise surface characterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional lasers are used for three-dimensional acquisition, then high power and depth of field are achieved, but resolution for millimetric objects is limited to hundred or tens of microns
Solution Approach 1:
The patent changes the fundamental parameter of the light source from coherent laser to incoherent LED, which eliminates speckle noise while achieving the required measurement precision for millimetric objects with micrometric resolution
2Reliability
If a single camera is used for profile acquisition, then device complexity is reduced, but blind spots in the image are present
Solution Approach 1:
The patent adds a second camera positioned at a different angular position to capture profiles from another viewing angle, eliminating blind spots and ensuring complete surface coverage for three-dimensional reconstruction
3Object-generated harmful factors
If LED is used to project light beam, then speckle noise is eliminated, but fringe thickness control to less than 50 μm is challenging
Solution Approach 1:
The patent introduces a mask with a thin opaque stripe as an intermediary element between the LED and the object, which precisely defines the fringe geometry and achieves the required thickness of less than 50 μm while using incoherent LED light
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 achieves micrometric resolution and depth field, effectively characterizing millimetric objects by reducing noise and blind spots, allowing for precise measurements of surface defects and roughness.
Implementation Method 1
the projection means comprise an LED whose light is focused in the form of a fringe
Implementation Method 2
an LED whose light is focused in the form of a fringe with a thickness of less than 50 μm
Implementation Method 3
at least one digital camera for acquiring images of the profile produced by said beam on the object
Data Source
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AI summary
The invention relates to an object surface three-dimensional acquisition system, comprising means for projecting a fine light beam, at least one digital camera for acquiring images of the profile produced by said beam on the object, means of displacement of the beam along the object, means for processing the images acquired. The system comprises an LED whose light is focused in the form of a fringe less than 50 μm thick.