Portable Structured Light Module with Fixed-Pattern Optic
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Solution Overview
Problem
Conventional Structured Light Illumination (SLI) systems are computationally heavy and have large footprints, making them impractical for real-time measurements in small spaces, such as within the mouth or inside machinery, due to the need for multiple projector units and complex electronic control systems.
Innovation Solution
A portable module employing a novel dual-frequency Phase Multiplexing (DFPM) and Period Coded Phase Measuring (PCPM) pattern strategy, combined with a compact projection system and image processing using Lookup Tables (LUTs), allows for real-time 3D surface measurement without the need for multiple projector units, using a single camera and projector system with a unique fixed-pattern optic and polarizing beam splitter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SLI systems use multiple projector units and complex electronic control systems to achieve high-resolution 3D measurements, then measurement precision is improved, but device complexity and footprint increase
Solution Approach 1:
The patent combines multiple projector units into a single integrated projection system that uses a single optical axis. The projection system integrates the light source, pattern generation, and projection optics into one compact module, eliminating the need for multiple separate projector units while maintaining the capability to project multiple structured light patterns for high-resolution 3D measurements.
Solution Approach 2:
The single optical axis is designed to serve multiple functions: it acts as both the projection axis for structured light patterns and the optical path for the camera to capture reflected light. This multi-functional design eliminates the need for separate projection and imaging optical paths, reducing device complexity while preserving measurement precision.
2Productivity
If conventional SLI systems use multiple projector units to achieve real-time measurements, then productivity is improved, but the footprint and space requirements increase
Solution Approach 1:
The patent merges multiple projector functions into a single compact projection module that maintains real-time measurement capability. By integrating the pattern projection and light emission functions into one unit aligned with the camera's optical axis, the system achieves real-time 3D measurements without requiring the large footprint of multiple distributed projector units.
3Measurement precision
If conventional SLI systems employ sophisticated electronic control systems for pattern projection, then measurement precision is improved, but ease of operation deteriorates
Solution Approach 1:
The projection system is designed to automatically generate and project the required structured light patterns without requiring complex external electronic control. The system self-regulates the pattern projection timing and synchronization with the camera capture, eliminating the need for sophisticated external control systems while maintaining high measurement precision.
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 high-resolution, real-time 3D surface measurements in various environments, including small spaces, with reduced computational complexity and equipment size, allowing for continuous monitoring without disrupting the surface environment.
Implementation Method 1
The novel SLI pattern that emerges from the linear pattern shifting device is directed through a polarizing beam splitter, the polarized light being then directed on through a lens assembly
Implementation Method 2
A portable module employing a novel dual-frequency Phase Multiplexing (DFPM) and Period Coded Phase Measuring (PCPM) pattern strategy
Implementation Method 3
The polarized light being then directed on through a lens assembly which, in operation, is uniquely structured to assist with both projection of the SLI pattern and camera functionalities
Implementation Method 4
This return light, having been redirected back through the unique lens assembly, exits same, then is directed into a camera image sensor
Data Source
AI summary
A surface measurement module for 3-D image acquisition of a subject-under-inspection. The module having: (a) a casing to house a pattern shifting device having a fixed-pattern optic through which light from a light source is passed, an output of the pattern shifting device being directed at a polarizing beam splitter and the polarized output of the splitter directed through a lens assembly comprising at least one lens element; (b) a reflector to direct the polarized output exiting the lens assembly, to illuminate a surface of the subject-under-inspection; (c) a scattered light illumination off the surface is directed back through the lens assembly for capture by an image sensor; and (d) the casing also housing the polarizing beam splitter, the lens assembly, and the image sensor. The output of the fixed-pattern optic comprises a multi-frequency pattern. The pattern shifting device may be a linear or rotating type.