Image Scanning Focus Estimation Using Merit Values
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Solution Overview
Problem
Existing image scanning apparatuses face inefficiencies in determining the in-focus position due to limited depth of focus, requiring numerous focus measurements and leading to time-consuming processes that reduce productivity.
Innovation Solution
A method that estimates the in-focus position during scanning by obtaining image information at nominal and additional focus levels, using focus parameters like merit values to calculate and adjust focus on-the-fly, allowing for rapid and accurate determination without pre-scanning or focus mapping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus is measured at multiple points using interpolation techniques, then measurement precision of in-focus position is improved, but loss of time increases significantly
Solution Approach 1:
The patent applies preliminary action by performing focus measurements at only a few strategic points (including edges and center) before the main scanning process, rather than measuring at every point. These preliminary measurements are then used to predict focus positions throughout the entire scan area, dramatically reducing measurement time while maintaining adequate precision through the prediction algorithm
Solution Approach 2:
The system uses self-service by leveraging the scan data itself to determine focus positions. The scanning process automatically provides image information that is analyzed to calculate focus parameters, eliminating the need for separate dedicated focus measurement procedures and reducing overall time loss
2Manufacturing precision
If focus is adjusted during the scan to maintain image quality, then manufacturing precision of image quality is improved, but device complexity increases
Solution Approach 1:
The patent applies dynamics by implementing a dynamic focus adjustment system that continuously adapts the focus position during scanning based on real-time analysis of image information. The focus parameter is calculated from scan data and used to adjust the focus mechanism on-the-fly, maintaining consistent image quality across surfaces with varying depth without requiring complex pre-programming or manual intervention
Solution Approach 2:
The system employs feedback by using the image information obtained during scanning to calculate focus parameters, which then feed back to control the focus adjustment mechanism. This closed-loop feedback ensures that focus is continuously optimized based on actual image quality metrics, maintaining manufacturing precision while using a relatively simple adjustment mechanism
Data Source
AI summary
A method is provided of estimating an in-focus position of a target in an image scanning apparatus. A first part of the target is scanned at a nominal focus level so as to obtain corresponding image information. One or more further parts of the target are scanned at one or more respective further focus levels so as to obtain corresponding image information. A focus parameter is then calculated for each of the nominal and the one or more further focus levels using the respective image information. An in-focus position common to each of the first and further parts of the target is then estimated using the calculated focus parameters. Corresponding apparatus for performing the method is also provided.