Digital Microscope Autofocusing via Dual Imaging Units
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Solution Overview
Problem
Current digital microscope systems face challenges in achieving high-speed and high-accuracy focusing processing, as existing autofocusing methods like contrast AF are time-consuming and phase difference AF compromises on accuracy.
Innovation Solution
A digital microscope apparatus with a first imaging unit for capturing enlarged images and a second imaging unit with a larger depth of field, where a controller calculates a provisional in-focus position using the second image to restrict the reading area and search for the in-focus position efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contrast AF is used to achieve high accuracy in focal point, then measurement precision is improved, but productivity deteriorates due to repetitive movements and evaluations taking relatively long time
Solution Approach 1:
The patent applies preliminary action by using the second imaging unit with larger depth of field to capture a preliminary in-focus position before the final high-precision focusing. This preliminary focusing step narrows down the search range for the subsequent contrast AF, reducing the number of repetitive movements and evaluations needed while maintaining high accuracy.
Solution Approach 2:
The patent segments the focusing process into two distinct stages: first using the second imaging unit for rough focusing with larger depth of field, then using the first imaging unit for precise focusing. This segmentation allows each stage to optimize for its specific function, improving overall efficiency without sacrificing accuracy.
2Productivity
If phase difference AF is used to achieve high speed focusing without search, then productivity is improved, but measurement precision deteriorates due to reduced accuracy
Solution Approach 1:
The patent merges two different autofocusing methods into a unified system: the second imaging unit provides rapid preliminary focusing (similar to phase difference AF speed), while the first imaging unit performs high-precision contrast AF. The combination achieves both high speed and high accuracy that neither method could achieve alone.
3Measurement precision
If the entire first imaging device is read to search for in-focus position, then measurement precision is improved, but loss of time increases due to reading large area
Solution Approach 1:
The patent applies local quality by restricting the reading area of the first imaging device to only the region around the provisional in-focus position identified by the second imaging unit. This localized reading approach maintains focusing accuracy while significantly reducing the time required to read and process image data.
Data Source
AI summary
A digital microscope apparatus includes a first imaging unit including a first imaging device and a first optical system including an objective lens configured to enlarge first and second images of a preparation that holds a sample, the first image being formed on the first device through the first system, a second imaging unit including a second optical system that is branched from the first system and has a depth of field larger than the first system and a second imaging device on which the second image is formed through the second system, and a controller configured to calculate a provisional in-focus position of the lens based on the second image, determine an area of the first device, from which the first image is read, and search for, based on the read image, an in-focus position of the lens in a predetermined range based on the provisional in-focus position.