Dual Line Scan Detector Focus Tracking for Irregular Samples
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Solution Overview
Problem
Existing virtual microscope techniques face challenges in maintaining focus over irregularly shaped biological samples, as they require extensive data collection or rapid focus adjustments, leading to inefficiencies and uncertainties in focus tracking.
Innovation Solution
A method using a first and second line scan detector with a focus shifting element to obtain image and focus scan lines at different focus levels, allowing for accurate estimation and adjustment of the in-focus level, enabling quicker and more precise focus tracking without complex systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple images at multiple focal planes are collected to maintain focus, then focus accuracy is improved, but data quantity and scanning time increase significantly
Solution Approach 1:
The patent extracts only the essential focus information needed for tracking by using a dedicated focus detector separate from the main imaging detector. This allows focus measurement without capturing complete image data at multiple focal planes, significantly reducing data quantity while maintaining focus accuracy.
Solution Approach 2:
The patent introduces an intermediary focus detector that specifically measures focus characteristics without requiring full image capture. This intermediary device enables focus tracking at multiple focal planes without the time penalty of processing complete multi-planar images.
2Measurement precision
If focus is measured at a number of points and linear interpolation is used to estimate focus, then a single in-focus image is produced, but the sample becomes out of focus in regions between measurement points when the sample is non-linear
Solution Approach 1:
The patent implements continuous focus monitoring and adjustment during the scanning process rather than relying on discrete measurements and interpolation. The focus detector continuously tracks focus characteristics, enabling real-time focus maintenance across the entire sample area without gaps or interpolation errors.
Solution Approach 2:
The patent employs feedback control where focus measurements are continuously taken and used to adjust the scanning system's focus in real-time. This closed-loop approach ensures the focus trajectory accurately follows the sample surface even when non-linear, eliminating the limitations of open-loop interpolation methods.
3Speed
If rapid movement of focus during scanning is implemented to maintain focus, then focus tracking capability is improved, but system complexity and mechanical stress increase
Solution Approach 1:
The patent replaces complex mechanical focus adjustment systems with a computational approach. Instead of rapidly moving mechanical focus components during scanning, the system uses a focus detector to measure focus characteristics and computationally determines the optimal focus trajectory, reducing mechanical complexity and stress while maintaining fast focus tracking.
4Reliability
If a single focus detector is used with an imaging detector, then focus can be maintained, but uncertainty about optimum focus position limits correction magnitude and slows tracking rate
Solution Approach 1:
The patent segments the detection function by using a dedicated focus detector separate from the imaging detector. This specialization allows the focus detector to optimally measure focus characteristics without the uncertainties inherent in using the imaging detector for both purposes, enabling more confident and faster focus corrections.
Data Source
AI summary
A method of estimating an in-focus level of a target in an image scanning apparatus, wherein the image scanning apparatus comprises a first line scan detector configured to obtain one or more image scan lines of the target and a second line scan detector configured to obtain one or more focus scan lines of the target, the second line scan detector comprising at least one focus shifting element such that each focus scan line is obtained at respective first and second focus levels, wherein the first focus level is different from the second focus level, the method comprising: obtaining at least one focus scan line of the target using the second line scan detector; obtaining at least one image scan line of the target using the first line scan detector, the image scan line being obtained at a respective third focus level; calculating at least one focus parameter using the at least one focus scan line; and estimating a nominal in-focus level of the target using the at least one focus parameter.