3D Surface Measurement via Multi-Angle Ray Bundle Illumination
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Solution Overview
Problem
Conventional 3D surface measurement techniques face challenges in achieving high depth resolution and accuracy due to limited field-of-view, sensitivity to environmental factors, and inability to capture reflectance properties like diffuse and specular reflections, especially on smoother specular surfaces.
Innovation Solution
A 3D surface measurement system employing an engineered illumination system that directs ray bundles with varying intensities to a surface from multiple illumination directions, coupled with a camera and sensor system to capture intensity images and determine surface normals, enabling the construction of surface normal maps and estimation of microgeometry and reflectance properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional techniques (white light interferometer, confocal microscope, focus variation) are used to measure surface depth with nanometer to micron-scale depth resolution, then measurement precision is improved, but field-of-view becomes narrow and working distance becomes short
Solution Approach 1:
The illumination is divided into multiple discrete ray bundles, each directed at different angles toward the surface. This segmentation of illumination directions allows the system to capture reflectance information from multiple angles simultaneously, enabling both high depth resolution and broader field-of-view without requiring physical movement of the illumination source.
Solution Approach 2:
The patent transitions from single-direction illumination to multi-directional illumination by introducing angular dimensionality. Multiple ray bundles illuminate the surface from different angles, adding a directional dimension to the measurement process. This enables the system to extract both depth information and reflectance properties simultaneously, resolving the contradiction between precision and field-of-view.
2Measurement precision
If conventional techniques use high magnification microscope objectives to achieve high depth resolution, then measurement precision is improved, but device complexity increases and cost increases
Solution Approach 1:
The patent replaces complex mechanical microscope objectives with a simpler optical illumination system. Instead of using high-magnification lenses and complex mechanical positioning systems, the invention uses multiple controlled light ray bundles at different angles. This substitution maintains measurement precision while dramatically reducing device complexity and eliminating the need for expensive microscope components.
3Measurement precision
If interferometry-based devices are used to achieve high depth resolution, then measurement precision is improved, but sensitivity to ambient environment (vibration) increases
Solution Approach 1:
The patent converts the challenge of environmental sensitivity into an advantage by using reflectance measurements. Instead of relying on interference patterns that are vulnerable to vibration, the system measures how surface microgeometry affects light reflection from multiple angles. This approach transforms potential harm (environmental sensitivity) into a beneficial measurement mechanism, as reflectance properties remain stable even in vibrating environments.
4Ease of operation
If photometric stereo technique is used to reconstruct surface normal and depth, then ease of operation is improved, but measurement precision deteriorates because the method assumes the scene to be Lambertian (diffusive)
Solution Approach 1:
The patent applies local quality by treating different surface regions with appropriate measurement models. Instead of assuming uniform Lambertian reflection across the entire scene, the system captures reflectance properties at multiple illumination angles and applies localized analysis to account for variations in surface properties. This allows accurate surface normal reconstruction for both diffusive and specular regions, maintaining simplicity while improving precision.
5Adaptability or versatility
If methods using hand-moved point light source or structured illumination are used to address microgeometry measurement on specular surfaces, then adaptability is improved, but measurement precision deteriorates because they can only capture images with limited number of lighting directions
Solution Approach 1:
The patent implements continuous useful action by providing uninterrupted multi-directional illumination across the entire surface simultaneously. Instead of moving a point light source or using discrete structured illumination patterns, the system maintains continuous illumination from multiple angles at once. This continuous multi-angular illumination enables both adaptability to specular surfaces and high measurement precision through sufficient sampling of the reflectance field.
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 high-resolution 3D surface measurements with improved accuracy and the ability to capture detailed microgeometry and reflectance properties, even on smoother specular surfaces, while reducing environmental sensitivity and increasing measurement precision.
Implementation Method 1
capture reflectance properties such as diffuse reflection and specular reflection
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3C
AI summary
Certain embodiments are directed to 3D surface measurement systems and methods configured to direct engineered illumination of beams in one or more ray bundles to N illumination directions incident a sample surface. The systems and methods can measure a map of surface normals, a depth map, and a map of surface properties using intensity images captured while the engineered illumination is directed to the sample surface.