Autofocus Device for Microscopy Using Intensity-Modulated Pattern
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Solution Overview
Problem
Existing microscopy techniques face challenges in precisely determining the focal plane of a sample and tracking objects within a sample volume, especially when dealing with varying depths and complex sample interfaces, often requiring additional autofocus devices or interrupting the measurement process for focus adjustments.
Innovation Solution
A microscope system incorporating an autofocus device with a light modulator generating a two-dimensional intensity-modulated modulation object, which is imaged into the sample volume using autofocus illumination optics and recorded by a camera, allowing for precise determination of the focal plane and object tracking without the need for a separate autofocus device or repeated focus adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate autofocus device is used to determine the reference plane, then the distance from the measurement plane to the reference plane can be determined, but the optical complexity increases and the detection or illumination aperture must be reserved for the additional autofocus
Solution Approach 1:
The single autofocus device is designed to perform multiple functions: it can focus on the measurement plane during normal operation and switch to focus on the reference plane when needed. This eliminates the need for a separate autofocus device while maintaining the capability to determine distances between planes. The beam splitter couples the autofocus beam path into the existing microscope beam path, allowing the same optical components to serve dual purposes.
Solution Approach 2:
The autofocus device dynamically adjusts its focus between the measurement plane and the reference plane as needed. The system can switch between focusing on the sample for measurement and focusing on the reference plane for distance determination, without requiring separate static autofocus paths. This dynamic switching capability reduces optical complexity while maintaining measurement precision.
2Measurement precision
If measurement is interrupted for focus adjustment to reference the autofocus device to the desired reference plane, then the distance from the measurement plane to the reference plane can be determined, but the actual microscopic measurement has to be interrupted
Solution Approach 1:
The reference plane is pre-established and stored in memory before the actual measurement begins. When distance determination is needed, the system quickly references this pre-stored information rather than requiring a full refocusing procedure. This allows the measurement to continue without interruption while still achieving precise distance determination.
Solution Approach 2:
The system uses feedback from the single autofocus device to continuously monitor and adjust the focus position. By comparing the current focus position with the stored reference plane position, the system can determine distances without interrupting the measurement flow. The autofocus device provides continuous feedback that enables real-time distance determination while maintaining measurement continuity.
3Measurement precision
If triangulation method is used for autofocus, then the z-position of the laser light reflected by the sample can be deduced, but image defects occur during imaging of laser light into planes at different depths and the autofocus quality varies significantly over a given depth-of-focus range
Solution Approach 1:
A beam splitter is introduced as an intermediary component that couples the autofocus beam path into the microscope beam path. This allows the autofocus laser to be reflected into the pupil plane of the objective without interfering with the main imaging beam path. The beam splitter mediates between the autofocus and imaging functions, enabling consistent autofocus quality across different depths by maintaining proper optical coupling without introducing image defects.
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 precise and efficient determination of the focal plane and object tracking within the sample volume, reducing optical complexity and measurement interruptions, while maintaining high precision and adaptability to different sample types and interfaces.
Implementation Method 1
an autofocus device, which is coupled into the microscope beam path by reflection on a beam splitter
Data Source
AI summary
A microscope including an objective, which images a sample along a microscope beam path, and an autofocus device, which is coupled into the microscope beam path via a beam splitter at a location behind the objective. A light modulator for generating a two-dimensional, intensity-modulated modulation object, is located in the autofocus beam path in a plane conjugated to the focal plane of the objective or intersects the latter and is imaged into the focal plane of the objective. A camera records a two-dimensional image onto which the modulation object's image is imaged. The image plane of the camera intersects a plane that is conjugated to the modulation object or is located in the plane and the camera detecting the contrast of the modulation object's image located in the sample.