Portable 3D Scanner Using Diffractive Optical Elements
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Solution Overview
Problem
Existing portable scanners face challenges in generating accurate 3D scans of objects with smooth surfaces and low feature density, as they struggle to effectively capture scattered light and maintain calibration stability during operation.
Innovation Solution
A portable 3D measurement device equipped with a projector, two cameras, and a control and evaluation unit, which uses epipolar geometry and diffractive optical elements to project and capture patterns, allowing for precise 3D scanning and automatic calibration, even in environments with limited features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a portable scanner uses traditional light projection methods, then it can capture objects with sufficient features, but it fails to accurately scan objects with smooth surfaces and low feature density
Solution Approach 1:
The patent applies coded light patterns with different spatial frequencies and encodings (e.g., binary, Gray code, sinusoidal patterns) to project onto the object surface. These varying light patterns create artificial features and contrast variations that enable accurate measurement of smooth surfaces that would otherwise lack sufficient natural features for 3D reconstruction.
Solution Approach 2:
The patent transitions from traditional single-dimension or two-camera stereo vision to a multi-dimensional approach by projecting structured light patterns and capturing their deformation across multiple wavelengths and spatial frequencies. This adds dimensional information (phase, frequency, amplitude modulations) that enables precise measurement of smooth surfaces.
2Ease of operation
If a portable scanner is designed for portability, then it can be easily transported and used on-site, but it may compromise calibration stability during operation
Solution Approach 1:
The patent implements real-time feedback mechanisms where the system continuously monitors the relative positions and orientations of the projector and camera(s) during operation. Calibration data is dynamically adjusted based on detected movements, ensuring measurement accuracy is maintained even as the portable device is repositioned or subjected to vibrations during field use.
Solution Approach 2:
The patent performs preliminary calibration procedures that establish baseline relationships between optical components before actual scanning begins. These pre-established calibration parameters serve as reference frameworks that can be quickly adjusted or compensated for during operation, maintaining stability without requiring the device to remain completely stationary.
3Measurement precision
If the scanner captures scattered light from smooth surfaces, then it can improve measurement accuracy, but it increases the complexity of light pattern detection and processing
Solution Approach 1:
The patent employs periodic light patterns such as sinusoidal fringes and repeating binary sequences that are projected onto the object surface. These periodic patterns create predictable modulation signatures in the captured images, enabling the system to distinguish scattered light from smooth surfaces against background noise through frequency domain analysis and phase-shifting algorithms.
Solution Approach 2:
The patent introduces mathematical processing intermediaries (phase-shifting algorithms, Fourier transform analysis, and pattern recognition software) that act as mediators between the captured scattered light and the final 3D reconstruction. These computational intermediaries decode the scattered light information by analyzing pattern deformations, converting complex optical signals into precise geometric data.
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 device achieves high-resolution 3D scans with improved calibration stability and accuracy, capable of handling objects with smooth surfaces and maintaining consistent performance over time.
Implementation Method 1
A portable scanner includes a projector that projects light patterns on the surface of an object to be scanned. Two (or more) cameras, the relative positions and alignment of which are known or are determined, can record images of the surface with a further, uncoded pattern.
Implementation Method 2
The illumination unit is used for generating a pattern in the target area, such as by means of a diffractive optical element.
Data Source
AI summary
A method for scanning and obtaining three-dimensional (3D) coordinates is provided. The method includes providing a 3D measuring device having a projector, a first camera and a second camera. The method records images of a light pattern emitted by the projector onto an object. The 3D measuring device is moved from a first position and a second position along a second path. A gesture and a corresponding control function are determined based at least in part on the first position and the second position.