Autofocus Device for Fluorescence Microscope Using Guide Beam
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Solution Overview
Problem
Fluorescence microscopes face challenges in maintaining focus over time due to photobleaching and the small depth of field caused by high numerical aperture objective lenses, leading to potential defocusing from minor changes in the distance between the objective lens and the sample.
Innovation Solution
An autofocus device with a guide beam generation unit and sample focus measurement unit that uses a guide beam independent of excitation light to measure and control the distance between the objective lens and the sample plane, minimizing photobleaching and maintaining accurate focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If excitation light is used for focusing in fluorescence microscopes, then the sample can be focused and imaged, but photobleaching occurs during focusing
Solution Approach 1:
The patent divides the light function into two separate systems: excitation light for fluorescence imaging and guide beam light for focusing. This segmentation allows the focusing function to be performed independently without using excitation light, thereby preventing photobleaching while maintaining focus accuracy.
Solution Approach 2:
The patent introduces a guide beam as an intermediary element that serves as a reference for focusing. The guide beam reflects off the sample surface and provides positional information to the detection unit, enabling focus control without directly illuminating the fluorescent sample for imaging.
2Quantity of substance
If high numerical aperture objective lens is used to collect fluorescent light, then fluorescence signal collection is improved, but depth of field becomes very small causing easy defocusing
Solution Approach 1:
The patent implements a feedback control system where the detection unit continuously monitors the position of the guide beam reflected from the sample. When the objective lens moves due to thermal changes or vibrations, the guide beam position changes, and the system automatically adjusts the lens position to maintain focus, providing stable imaging despite small depth of field.
Solution Approach 2:
The guide beam system automatically detects and compensates for focus drift caused by thermal expansion, contraction, or vibrations. The system self-regulates the objective lens position based on real-time guide beam position feedback, eliminating the need for manual refocusing and maintaining stable focus continuously.
3Ease of operation
If manual focus adjustment is used in conventional optical microscopes, then focus can be maintained, but automatic focus maintenance is not available
Solution Approach 1:
The patent employs a closed-loop feedback control system where the detection unit continuously monitors guide beam position and automatically adjusts the objective lens position via the drive unit. This automated feedback mechanism replaces manual focus adjustment while maintaining ease of operation through automatic compensation for environmental changes.
4Measurement precision
If the distance between objective lens and sample changes due to thermal shrinkage or expansion, then focus is maintained initially, but defocusing occurs over time
Solution Approach 1:
The patent implements continuous monitoring and adjustment of the objective lens position through the guide beam feedback system. Unlike initial manual focusing, the system continuously detects guide beam position changes and makes real-time adjustments, maintaining focus accuracy throughout extended observation periods despite thermal fluctuations.
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
The autofocus device effectively reduces photobleaching and accurately maintains focus over a wider range of distances, enhancing the precision and accuracy of fluorescence microscopy observations.
Implementation Method 1
a sample focus measurement unit measuring the guide beam reflected from the sample plane to detect a change in distance between the sample plane and an objective lens
Data Source
AI summary
The present invention relates to an autofocus device for an optical microscope that can accurately maintain the focus of an optical microscope, which is used to observe a sample using light, for a long period of time and a method for maintaining the focus. The autofocus device of the present invention includes a guide beam generation unit installed in a light source part of a fluorescence microscope to supply a guide beam in a direction towards a sample plane and a sample focus measurement unit measuring the guide beam reflected from the sample plane to detect a change in distance between the sample plane and an objective lens.