Dynamic Specimen Tilt for Focus Maintenance in Slide Scanning
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Solution Overview
Problem
Existing microscopic imaging technologies face challenges in maintaining focus across large specimens, especially when specimens are not flat or tilted, leading to focus mismatches between adjacent image strips, particularly in brightfield and fluorescence imaging.
Innovation Solution
The implementation of a scanning optical microscope that dynamically tilts the specimen about the scan direction during scanning, allowing for simultaneous focus and tilt adjustments to maintain focus along the length of each scan line, using methods such as piezo positioners and computer-controlled systems to adjust focus and tilt in real-time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high Numerical Aperture microscope objective is used to image large specimens, then imaging resolution is improved, but depth of field decreases making it difficult to maintain focus across the entire specimen
Solution Approach 1:
The patent applies dynamics by making the specimen stage tiltable during the imaging process. The stage angle is dynamically adjusted based on the measured focus variation across the specimen, allowing the focal plane to match the specimen's topography. This dynamic adjustment resolves the contradiction by enabling high NA imaging while maintaining focus across large, non-flat specimens.
Solution Approach 2:
The patent changes the parameter of stage tilt angle to compensate for focus issues. By measuring the focus position at multiple locations and calculating the optimal tilt angle, the system adjusts the stage orientation to bring the entire specimen into focus, thereby maintaining both high resolution and focus accuracy.
2Manufacturing precision
If the specimen is tilted to maintain focus across the scan area, then focus uniformity is improved, but the specimen holder and imaging geometry become more complex
Solution Approach 1:
The patent segments the focus correction problem by measuring focus at discrete locations across the specimen and calculating tilt parameters based on these measurements. This segmented approach simplifies the control mechanism compared to continuous adjustment systems, as it only requires setting the stage tilt angle based on pre-measured focus data.
3Area of stationary object
If multiple image tiles are stitched together to cover large specimens, then the imaged area is increased, but tiling artifacts and focus mismatches between adjacent tiles increase
Solution Approach 1:
The patent performs preliminary focus measurements and calculates the optimal stage tilt angle before acquiring the full set of image tiles. This preliminary action ensures that all subsequent tiles are acquired with consistent focus settings, eliminating focus mismatches at tile boundaries and reducing stitching artifacts.
4Productivity
If the scan speed is increased to reduce imaging time, then productivity is improved, but focus maintenance becomes more difficult due to vibrations and motion blur
Solution Approach 1:
The patent applies dynamics by continuously monitoring and adjusting the stage tilt angle during the scanning process. This real-time dynamic adjustment compensates for vibrations and motion-induced focus changes, allowing high-speed scanning while maintaining focus stability and image quality.
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 effectively maintains focus across the width of the scan strip and ensures that adjacent strips are acquired at the same focus positions, reducing image artifacts and enabling high-resolution imaging of large specimens without the need for extensive focus mapping.
Implementation Method 1
focused on the specimen by piezo positioner 120
Implementation Method 2
infinity-corrected microscope optics are used, with a high Numerical Aperture (high NA) microscope objective and a tube lens of the appropriate focal length to focus an image of the specimen directly onto a CCD or CMOS linear array sensor
Data Source
AI summary
An instrument and method for scanning large microscope specimen on a specimen holder has a scanning optical microscope that is configured to scan the specimen in one of brightfield and fluorescence. The specimen is dynamically tillable about a scan direction during a scan to maintain focus along the length of each scan line as the scan proceeds. A three dimensional image of the specimen can be obtained wherein the specimen tilt and relative focus are maintained from a first image contour to a second image contour through a thickness of a specimen.