Lens Parameter Measurement via Segmented Test Pattern Imaging
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Solution Overview
Problem
Existing methods for measuring lens parameters in optical fingerprint systems are inadequate, leading to issues with fingerprint image collection and identification due to defocus problems.
Innovation Solution
A method and device for measuring lens parameters using a measuring member with a test pattern on the object side of the lens and an imaging module on the image side, which acquires central and edge imaged images to determine lens parameters based on imaging quality parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing methods for measuring lens parameters are used, then the measurement process is simple, but the measurement precision is inadequate leading to defocus problems
Solution Approach 1:
The patent divides the test pattern into multiple regions (first test pattern region and second test pattern region) with different characteristics. The first region contains test patterns at different positions to assess central and edge imaging quality, while the second region provides additional reference patterns. This segmentation allows the system to measure multiple lens parameters (defocus amount, astigmatism, distortion) simultaneously using a single integrated measurement process, improving precision without proportionally increasing device complexity.
Solution Approach 2:
The patent introduces a measuring member with specifically designed test patterns as an intermediary between the lens and the imaging module. This measuring member contains encoded information about the lens parameters through its test pattern design, allowing the imaging module to capture and process information that directly reveals lens performance characteristics. The intermediary converts complex lens parameter measurement into a simpler image capture and processing problem.
2Reliability
If defocus amount is not accurately measured, then the lens module can be manufactured quickly, but fingerprint image collection and identification are affected
Solution Approach 1:
The patent performs lens parameter measurement during the manufacturing process using the measuring member with test patterns before the lens is installed in the final fingerprint module. By conducting these measurements preliminarily, the system can identify and filter out lenses with excessive defocus or astigmatism before assembly, ensuring that only quality-approved lenses are used. This preliminary measurement action guarantees reliable fingerprint image quality while maintaining efficient manufacturing throughput.
Solution Approach 2:
The patent establishes a feedback mechanism where the imaging module captures images of the test patterns, processes these images to determine lens parameters (defocus amount, astigmatism, distortion), and uses this information to assess lens quality. The measurement results feed back to determine whether the lens meets specifications, allowing for quality control and selection. This feedback loop ensures reliable fingerprint imaging performance while maintaining manufacturing efficiency through automated 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 provides better measurement performance for lens parameters, improving fingerprint image quality and identification accuracy by accurately determining the defocus amount and lens parameters.
Implementation Method 1
an imaging module provided on an image side of the to-be-measured lens and configured to image the at least single-sided test pattern of the measuring member to form an imaged image
Data Source
AI summary
The present disclosure provides a method for measuring a lens parameter and a device for measuring a lens parameter. The measuring method includes: acquiring an imaged image of the at least single-sided test pattern of the measuring member formed by the imaging module; obtaining a central imaged image and an edge imaged image based on the imaged image, wherein the central imaged image and the edge imaged image are at least partially non-overlapping, and the central imaged image is closer to a center of the imaged image than the edge imaged image; acquiring a central imaging quality parameter based on the central imaged image, and acquiring an edge imaging quality parameter based on the edge imaged image; and determining the lens parameter of the to-be-measured lens based on the central imaging quality parameter and the edge imaging quality parameter.