Optical Grating Pattern Projection for 3D Surface Reconstruction
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Solution Overview
Problem
Current 3D sensors face limitations in achieving fast and accurate image acquisition of structured surfaces due to slow projection speeds, low illumination intensity, and non-homogeneous brightness distribution, especially when using deterministic pattern sequences with analog gray value representation.
Innovation Solution
A method utilizing a pattern projection unit that generates patterns through diffraction on an optical grating, employing a MEMS light modulator with metal strips or plates for electrostatic movement, enabling high-speed gray value pattern generation and accurate reconstruction using phase evaluation or temporal correlation methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If deterministic pattern sequences with analog gray value representation are used, then measurement accuracy is improved, but projection speed is limited
Solution Approach 1:
The patent replaces mechanical pattern projection systems (such as rotating discs or motor-driven mirrors) with an optical grating-based system. The optical grating is illuminated by a laser source and projects patterns through diffraction, eliminating mechanical moving parts and enabling much faster pattern projection speeds while maintaining measurement accuracy through precise optical control.
Solution Approach 2:
The patent changes the projection mechanism from mechanical movement to optical diffraction parameters. By controlling the illumination of the optical grating and utilizing diffraction physics, the system achieves faster pattern projection speeds while maintaining the deterministic pattern sequences necessary for accurate measurement through phase evaluation.
2Illumination intensity
If laser-based light sources are used, then illumination intensity is improved, but power loss in modulators increases
Solution Approach 1:
The patent extracts the pattern modulation function from the light source itself and separates it into a dedicated optical grating component. The laser source provides high-intensity illumination, while the optical grating handles the pattern modulation through diffraction. This separation allows the laser to operate at full power without the energy loss problems associated with modulating laser light directly in conventional systems.
Solution Approach 2:
The optical grating acts as an intermediary between the laser source and the projection surface. It receives high-intensity laser light and converts it into the desired pattern through diffraction, serving as a mediator that enables high illumination intensity while managing energy distribution more efficiently than direct laser modulation.
3Productivity
If image acquisition time is reduced, then productivity is improved, but imaging unit sensitivity requirements increase
Solution Approach 1:
The patent employs preliminary action by using a laser source to pre-illuminate the optical grating with high intensity before the pattern is projected onto the object. This ensures that sufficient light is available for the imaging unit to capture patterns at very short exposure times, maintaining both high productivity and adequate detection sensitivity.
Solution Approach 2:
The system uses periodic action through the temporal correlation method, where multiple pattern sequences are projected and recorded in sequence. The periodic projection of patterns allows the imaging unit to operate at high speeds while the correlation algorithm processes the periodic data to achieve accurate measurements, effectively decoupling the speed requirement from the sensitivity requirement.
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 very fast and accurate three-dimensional reconstruction of surfaces with high energy density and homogeneous brightness, overcoming previous limitations in projection speed and image acquisition time.
Implementation Method 1
generates patterns using diffraction on an optical grating
Implementation Method 2
MEMS light modulator with metal strips or plates for electrostatic movement
Data Source
AI summary
The aim of the invention is a quick and very precise reconstruction of an object. This is achieved by a device and a method for detecting an image of a preferably structured surface of an object (6), comprising at least one pattern projection unit for illuminating the object (6) and at least one imaging unit (7) for capturing images of projected patterns. A temporal and/or spatial analysis of received images or image sequences is carried out in order to reconstruct the surface. The at least one pattern projection unit is designed to generate patterns using a diffraction of light on an optical grating. Furthermore, the method for detecting images is characterized in that by using the temporal and/or spatial analysis of the captured images or image sequences, corresponding pixels are ascertained by means of algorithms, said pixels together with an imaging function allowing a triangulation of surface points.