3D Inspection Camera System Using Polarization Analysis
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Solution Overview
Problem
Existing automated 3D inspection systems face challenges in achieving rapid, accurate, and cost-effective measurement of 3D coordinates of objects, particularly in accurately determining normal vectors to surfaces with varying materials and illumination angles.
Innovation Solution
A method utilizing a camera system with multiple linear polarizers oriented at different angles to form images of an object, which are then processed to determine 3D coordinates based on reference models, angle of polarization, and degree of linear polarization, enabling accurate reconstruction of object surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional 3D inspection systems use omnidirectional illumination, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical omnidirectional illumination system with an optical polarization-based system. Instead of using multiple light sources positioned around the object, the invention uses a single illumination source combined with polarization filters and cameras to achieve accurate surface normal vector determination through polarization analysis of reflected light
Solution Approach 2:
The invention changes the measurement parameter from direct geometric analysis under omnidirectional light to polarization state analysis. By measuring the polarization angle and degree of linear polarization of reflected light at different polarization filter orientations, the system can derive surface normal vectors without requiring complex omnidirectional illumination
2Measurement precision
If multiple cameras with polarizers are used to improve 3D measurement accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the measurement process into multiple discrete polarization angle measurements. By taking images through polarizers at different known angles (e.g., 0°, 45°, 90°, 135°) and processing these segmented measurements separately before combining them, the system achieves accurate 3D reconstruction while using a simpler camera setup than traditional multi-camera systems
Solution Approach 2:
The invention makes a single camera system perform multiple measurement functions by rotating polarization filters. The same camera can measure surface normals at different orientations by changing the polarization filter angle, eliminating the need for multiple fixed cameras positioned at different angles
3Productivity
If rapid 3D inspection is implemented to increase productivity, then output per unit time is improved, but measurement precision may deteriorate
Solution Approach 1:
The patent uses periodic action by rotating polarization filters through a sequence of predetermined angles in rapid succession. This periodic rotation allows the system to collect all necessary polarization data for accurate 3D measurement in a single rapid scanning cycle, maintaining both speed and precision
Solution Approach 2:
The invention performs preliminary action by pre-calculating and storing the relationship between polarization angles and surface normal vectors. During rapid inspection, the system only needs to capture images at the predetermined angles and apply pre-computed algorithms, eliminating the need for complex real-time calculations and enabling high-speed accurate measurement
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 rapid, accurate, and cost-effective 3D coordinate measurement, improving surface normal vector determination and reducing errors associated with non-omnidirectional illumination.
Implementation Method 1
a first linear polarizer oriented at a first angle, a second linear polarizer oriented at a second angle, and a third linear polarizer oriented at a third angle
Data Source
AI summary
A method of determining machined characteristics of a surface with a camera system, the camera system operable to obtain six camera images. The camera images are formed by illuminating the surface with light at each of two different angles. After reflecting off the surface, the light is passed through a polarizer at each of three different angles.