Microscope Autofocusing via Interference Pattern Analysis
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Solution Overview
Problem
Existing autofocus methods in microscopy are prone to errors and inaccuracies due to thermal drift and imperfections in the sample interface, leading to slow and imprecise focus adjustments, especially in long-term examinations of living cells or samples under thermal and vibrational influences.
Innovation Solution
The method employs interferometry to split the autofocus beam path into interfering partial beams, which are reflected off a reflective interface and detected as an interference pattern, allowing for precise focus adjustment based on changes in the interference pattern's orientation, density, and phase angle, with a deflection device using spaced-apart reflective areas to generate a focus-sensitive interference pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If position-detecting autofocus devices (triangulating autofocus) are used, then focus adjustment can be performed, but measurement precision deteriorates due to thermal drift and interface imperfections
Solution Approach 1:
The patent replaces the mechanical position-detecting autofocus system with an optical interferometry-based system. Instead of using triangulating beams and position-sensitive detectors to mechanically detect focus position, the system uses interference patterns of light waves to optically measure focus status, thereby achieving higher precision immune to thermal drift and mechanical imperfections
Solution Approach 2:
The patent changes the measurement parameter from mechanical position detection to optical interference pattern analysis. By monitoring changes in interference pattern characteristics (fringe spacing, contrast, phase) rather than mechanical beam position, the system achieves more stable and precise focus measurement that is unaffected by thermal expansion or mechanical deformation
2Ease of operation
If image content analysis autofocus methods are used, then focus detection can be performed, but speed deteriorates leading to slow focus adjustments
Solution Approach 1:
The patent replaces image content analysis methods with optical interferometry. Instead of analyzing image content to detect focus (which is computationally intensive and slow), the system directly measures focus status through optical interference patterns, providing real-time, high-speed focus detection without the computational delays inherent in image processing methods
3Ease of operation
If autofocus is set to a defined interface with offset, then ease of operation improves, but reliability deteriorates due to errors in distance knowledge
Solution Approach 1:
The patent implements a feedback mechanism where the interference pattern from the autofocus beam is continuously monitored and used to automatically adjust the focus position. This closed-loop feedback system eliminates the need for manual offset setting and provides continuous correction based on actual focus status, thereby improving reliability while maintaining ease of operation
Solution Approach 2:
The system performs self-adjustment by automatically detecting focus status through interference patterns and correcting focus position without requiring user intervention for offset calibration. The autofocus system serves itself by continuously monitoring and adjusting based on real-time interference data, eliminating errors associated with manual offset setting
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 enables rapid and precise autofocusing with reduced susceptibility to errors, allowing for continuous focus maintenance during microscopic examinations, even under thermal and vibrational changes, by using the interference pattern's characteristics to control focus adjustments.
Implementation Method 1
the deflection device has two areas arranged one behind the other in the direction of propagation of the autofocus beam path, which each reflect at least part of the autofocus beam path
Implementation Method 2
generate interfering partial beams of the autofocus beam path... generate an interference pattern
Data Source
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AI summary
The invention relates to an autofocusing method for use in the microscopic examination of an object (3) lying in the focus of a microscope objective (2) of a microscope (1), using an autofocus beam path (4), wherein the autofocus beam path (4) is directed toward the microscope objective (2) by means of a deflecting device (5) arranged on the side of the microscope objective facing away from the object and from there to a reflective autofocus interface (7) in the object region, and the autofocus beam path (4) reflected on the autofocus interface (7) is directed toward an autofocus detector (9) by means of the microscope objective (2) and the deflecting device (5), wherein the deflecting device (5) has two regions (51, 52; 53, 54), which are arranged at a distance from each other in the propagation direction of the autofocus beam path (4) and which each reflect the autofocus beam path (4), for producing interfering sub-beams (41, 42, 43, 44) of the autofocus beam path (4), and wherein the autofocus detector (9) is arranged in a plane conjugate to that of the microscope objective aperture in order to detect an interference pattern produced there, wherein the focus of the microscope (1) is adjusted according to the detected interference pattern (10).