Gemstone Inclusion Mapping with Surface-Normal OCT Correction
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Solution Overview
Problem
Existing techniques for detecting and accurately mapping artefacts in gemstones, such as diamonds, are limited by poor contrast, the need for toxic refractive index matching materials, and high computational complexity, making them impractical for efficient and reliable imaging.
Innovation Solution
A method and system using optical tomography processes, including surface and sub-surface mapping with optical coherence tomography (OCT), to determine the location of artefacts in gemstones without destructive sample preparation, using surface normals and refractive corrections to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If X-ray micro-computed tomography (XCT) is used for imaging, then geometric accuracy and non-invasive analysis are achieved, but contrast for all types of artefacts is poor and not all inclusion types can be identified
Solution Approach 1:
The patent combines multiple imaging modalities (optical projection tomography, optical coherence tomography, and X-ray computed tomography) into a unified system that acquires and processes data from all three techniques simultaneously or sequentially, allowing the strengths of each modality to complement the others and achieve both geometric accuracy and comprehensive inclusion detection
Solution Approach 2:
The patent uses composite refractive index matching materials composed of multiple components (such as mixtures of oils, waxes, or resins with different refractive indices) to match the refractive index of diamond more effectively, thereby improving optical contrast for inclusion detection while maintaining geometric accuracy
2Loss of information
If optical projection tomography (OPT) is used with refractive index matching materials, then most inclusion types can be detected, but toxic materials are required and sample contamination occurs
Solution Approach 1:
The patent changes the refractive index parameter of the matching material dynamically by using temperature-controlled materials or materials whose refractive index can be adjusted, allowing optimal matching for different inclusion types without requiring toxic substances, thereby detecting inclusions without contaminating the sample
Solution Approach 2:
The patent employs biodegradable or easily removable matching materials that can be safely disposed of or washed away without causing long-term contamination, replacing persistent toxic materials with environmentally friendly alternatives that achieve the same optical matching function temporarily during imaging
3Ease of manufacture
If optical projection tomography (OPT) is used without refractive index matching, then sample preparation is simplified, but light scattering prevents accurate 3-dimensional mapping
Solution Approach 1:
The patent introduces a non-toxic refractive index matching liquid as an intermediary substance between the optical beam and the gemstone sample, which reduces light scattering without requiring complex sample preparation, thereby maintaining both ease of use and mapping accuracy
Solution Approach 2:
The patent performs preliminary surface mapping and geometric characterization of the sample before the main tomography imaging, allowing the system to pre-calculate correction factors for light path deviations and apply these corrections during 3-dimensional reconstruction, thereby achieving accurate mapping without requiring refractive index matching materials
4Loss of information
If post processing fusion of multiple imaging techniques is used, then imaging results beyond single technique limitations are achieved, but large amounts of computing power are required and results may be unstable
Solution Approach 1:
The patent performs preliminary data preprocessing and feature extraction from each imaging modality before fusion, organizing the data into standardized formats and identifying key features in advance, which reduces the computational burden during the fusion process and improves result stability
Solution Approach 2:
The patent replaces complex iterative computational fusion algorithms with a streamlined integration approach that uses predetermined weighting factors and fusion rules based on the complementary strengths of each modality, reducing computational complexity while maintaining imaging completeness
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, high-resolution mapping of artefacts in gemstones, improving detection accuracy and reducing the need for toxic materials, while minimizing computational complexity.
Implementation Method 1
operating at optical wavelengths has the detrimental effect of introducing complexity in the interaction between the sample and optical light. In standard OPT applications for (rough) diamond imaging, samples need to be submerged in refractive index matching materials to reduce the scattering and make light paths entering the sample approximately straight lines
Implementation Method 2
optical coherence tomography (OCT) performs 3D imaging by measuring the reflective and back-scattering profile across the sample using low coherence interferometry
Implementation Method 3
measuring the reflective and back-scattering profile across the sample
Data Source
AI summary
A method and system for determining a location of artefacts and/or inclusions in a gemstone, mineral or sample thereof, the method comprising: surface mapping a gemstone, mineral or sample thereof to determine surface geometry associated with at least a portion of a surface of the gemstone, mineral or sample thereof; sub-surface mapping the gemstone, mineral or sample thereof using an optical beam that is directed at the surface along an optical beam path, wherein the optical beam is generated by an optical source using an optical tomography process; determining a surface normal at the surface at an intersection point between the optical beam path and the determined surface geometry; determining relative positioning between the surface normal and the optical beam path; and determining the location of artefacts and/or inclusions in the gemstone, mineral or sample thereof based on the sub-surface mapping step and the determined relative positioning.