Real-time Autofocus Algorithm for Digital Pathology Scanning
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Solution Overview
Problem
Conventional digital pathology scanning devices require significant time for pre-scan processing to acquire focus points across a glass slide, leading to inefficiencies in the scanning process.
Innovation Solution
A digital pathology scanning apparatus that includes an imaging sensor and a focusing sensor, where the processor analyzes image data to determine the optimal focus position of the objective lens by calculating contrast ratios and identifying a parfocal point, allowing for real-time autofocus adjustments during scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional pre-scan processing is used to acquire focus points across the glass slide, then focus accuracy is improved, but scanning time increases significantly
Solution Approach 1:
The patent extracts the focus detection function from the main imaging sensor by introducing a dedicated focusing sensor. This focusing sensor is specifically designed to detect focus information through contrast analysis, while the imaging sensor concentrates on capturing image data. This separation allows focus acquisition to occur rapidly during scanning without requiring time-consuming pre-scan processing of the full image data.
Solution Approach 2:
The patent applies local quality by having different sensors perform different functions: the focusing sensor is optimized for contrast detection to determine focus position, while the imaging sensor is optimized for image capture. The focusing sensor analyzes contrast values at specific positions to generate focus information, allowing rapid focus determination without processing the entire image dataset.
2Extent of automation
If a dedicated focusing sensor is added to the scanning apparatus, then real-time autofocus capability is improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by having the focusing sensor serve dual purposes: it detects focus information through contrast analysis and simultaneously provides positional reference data for the autofocus algorithm. The sensor system is designed so that the focusing sensor and imaging sensor work together in an integrated manner, with the focusing sensor enabling real-time focus detection without requiring a completely separate complex focusing system.
3Measurement precision
If the focusing sensor is tilted to achieve parfocal alignment, then focus detection accuracy is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs feedback by using the contrast values detected by the focusing sensor to determine the focus position, and then using this information to calculate the required autofocus adjustment. The system continuously monitors contrast ratios and uses this feedback to dynamically adjust the objective lens position, compensating for any initial alignment variations and achieving accurate focus without requiring extremely tight manufacturing tolerances.
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
Enables rapid and accurate focusing, reducing the time needed to scan a glass slide and improving the efficiency of the digital pathology scanning process.
Implementation Method 1
the processor may determine a ratio of the focusing sensor contrast value divided by the imaging sensor contrast value for each pixel. The processor may graph the contrast ratios to generate a contrast curve.
Data Source
AI summary
A digital scanning apparatus is provided that includes imaging and focusing sensors and a processor to analyze the image data captured by the imaging and focusing sensors and adjust the focus of the scanning apparatus in real time during a scanning operation. The individual pixels of the imaging sensor are all in the same image plane with respect to the optical path of the digital scanning apparatus. The individual pixels of the focusing sensor are each in a different image plane with respect to the optical path, and one pixel of the focusing sensor is on the same image plane as the image sensor. The processor analyzes image data from the imaging sensor and the focusing sensor and determines a distance and direction to adjust the relative position of an objective lens and a stage of the digital scanning apparatus to achieve optimal focus during the scanning operation.