Counterposed 3D Sensor Channels for Specular Surface Profilometry
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Solution Overview
Problem
Traditional optical metrology systems struggle with obtaining precise dimensional information from components with reflective specular surfaces and experience measurement errors due to specular reflections and intensity gradients, especially as components shrink and require higher magnification and resolution.
Innovation Solution
An optical phase profilometry system using multiple coaxial illumination source/imaging system pairs with a counterposed channel configuration, where each pair shares a common optical path and forms complementary channels that compensate for measurement errors by combining estimations in a way that cancels them out.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical metrology systems are used to measure reflective specular surfaces, then the system structure remains simple, but measurement precision deteriorates due to specular reflections and intensity gradients
Solution Approach 1:
The system divides the measurement task into multiple channels, each capturing reflections from different angles. By segmenting the optical paths and using separate camera-projector pairs for different viewing angles, the system can process specular reflections from multiple perspectives and combine them to eliminate measurement errors.
Solution Approach 2:
The patent employs asymmetric optical paths where camera-projector pairs are positioned at different angles relative to the measurement target. This asymmetric configuration allows each channel to capture different reflection characteristics, enabling the system to differentiate between actual surface geometry and specular reflection artifacts.
2Measurement precision
If higher magnification and resolution optics are used for smaller components, then measurement precision improves, but measurement errors from specular reflections and intensity gradients worsen
Solution Approach 1:
The system uses multiple channels with feedback loops that compare measurements from different optical paths. By iteratively comparing and reconciling data from channels with different viewing angles, the system can identify and correct errors introduced by specular reflections and intensity gradients, maintaining high precision even with high-magnification optics.
Solution Approach 2:
The patent adds the dimension of viewing angle by employing multiple camera-projector pairs positioned at different orientations. This multi-dimensional approach transforms a two-dimensional measurement problem into a three-dimensional one, allowing the system to resolve ambiguities caused by specular reflections by observing the target from multiple angular perspectives.
3Reliability
If traditional single-channel systems are used, then device complexity remains low, but reliability of dimensional measurement deteriorates due to uncorrected measurement errors
Solution Approach 1:
The system merges measurements from multiple camera-projector pairs by combining their respective point cloud data. By integrating data from channels with different optical paths and viewing angles, the system creates a more reliable and accurate dimensional representation that compensates for errors present in individual channels.
Solution Approach 2:
The patent changes key system parameters by using multiple camera-projector pairs with different angular configurations. This parameter diversification allows the system to capture varying reflection patterns and intensity distributions, enabling error correction through comparative analysis and improving overall measurement reliability.
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 system effectively reduces measurement inaccuracies caused by specular reflections and intensity gradients, providing accurate dimensional information by iteratively refining point clouds from counterposed channels.
Implementation Method 1
Optical phase profilometry systems have been employed to accurately measure and obtain precision dimensional information relative to a surface object
Implementation Method 2
certain technologies are reducing in size (e.g. circuit boards and components and/or device thereupon) and requiring higher magnification and higher resolution optics in order to obtain accurate dimensional information. Traditional optical metrology systems experience a variety of measurement errors from a variety of factors as the size and surface reflectivity of applications advance and change
Data Source
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AI summary
An optical phase profilometry system (1300) includes a first operative coaxial camera-projector pair (1302) aligned at a first angle relative to a target surface (1318) that projects a first illumination on the target surface and a second operative coaxial camera-projector pair (1304) aligned at a second angle relative to the target surface that projects a second illumination on the target surface. Wherein the first and second angles are equal and opposite to one another relative to the target surface such that the second operative coaxial camera-projector pair (1304) is configured to capture a first reflection from the first illumination and the first operative coaxial camera-projector pair (1302) is configured to capture a second reflection from the second illumination. The optical phase profilometry system (1300) further includes a controller (1356) configured to, based on the captured first and second reflections, generate a first and second estimation of the target surface (1318) and combine them to generate a dimensional profile of the target surface (1318).