Surface Profiling System Using GRIN Lens Optical Channels
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Solution Overview
Problem
Existing surface profiling systems face challenges in determining highly accurate surface height measurement coordinates, particularly in constrained spaces due to limitations in resolution and accuracy.
Innovation Solution
A surface profiling system incorporating an imaging detector array and an optical imaging array with overlapping fields of view, utilizing GRIN lenses to provide erect images and determine image offsets, allowing for precise surface height measurement coordinates through signal processing and control operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional surface profiling systems are used, then they can operate in constrained spaces, but they achieve low measurement precision (10 um accuracy)
Solution Approach 1:
The system divides the imaging function into multiple optical channels (at least two) with overlapping fields of view, where each channel images a portion of the workpiece surface. This segmentation allows the system to achieve higher measurement precision through multi-view geometry while operating in constrained spaces by using compact optical paths with GRIN lenses.
Solution Approach 2:
The patent introduces a new dimension of measurement by capturing images from multiple optical angles simultaneously. The image offset between overlapping IFOVs provides depth information, transforming 2D image data into 3D surface height measurements with 1 um accuracy, representing a dimensional enhancement from conventional single-view systems.
2Measurement precision
If multiple optical channels with overlapping FOVs are used, then measurement precision improves to 1 um, but the device complexity increases
Solution Approach 1:
Each optical channel in the array is designed to perform multiple functions: imaging workpiece surface features, providing overlapping IFOVs for depth measurement, and contributing to the composite image through signal processing. This multi-functionality reduces overall device complexity by eliminating the need for separate depth-sensing mechanisms.
Solution Approach 2:
The system creates optical copies of the workpiece surface from different angles through multiple optical channels. These optical copies (images) are then processed to extract depth information, replacing the need for physical contact probes or complex interferometric setups while achieving 1 um measurement precision.
3Manufacturing precision
If GRIN lenses are used to provide erect images, then imaging accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The patent utilizes GRIN lenses with specific gradient index parameters to achieve erect images at controlled object distances. By optimizing the GRIN lens parameters (gradient coefficient, length, diameter), the system achieves high manufacturing precision in image quality while maintaining ease of manufacture through standardized lens components that can be integrated into the optical channel array.
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 achieves improved accuracy in surface height measurement coordinates, enabling precise profiling in constrained spaces with enhanced resolution and accuracy, such as in bore inspection, with image offsets determined with sensitivity in the range of 1 um compared to 10 um, offering a 10x accuracy improvement over prior techniques.
Implementation Method 1
Each optical channel includes a lens arrangement (e.g., including a GRIN lens) configured to provide an erect image in its IFOV for a workpiece surface located in its FOV and within a measuring range along the direction of the optical axes of the surface profiling system
Data Source
AI summary
A surface profiling system is provided including an imaging detector array and an optical imaging array comprising at least one set of optical channels. Each optical channel includes a lens arrangement (e.g., including a GRIN lens) configured to provide an erect image at a detector. The optical channels have overlapping fields of view (FOV) and overlapping imaged fields of view (IFOV). A workpiece surface point may be simultaneously imaged in at least two overlapping IFOVs of two optical channels. A surface point that is not at an object reference distance (e.g., a front focal length) may be imaged at different respective positions along the imaging detector array, and the difference between the respective positions may define a respective image offset for that surface point. A surface height measurement coordinate for the surface point may be determined based on the corresponding image offset.