Autofocus Control Using Electrically Tunable Lens
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Solution Overview
Problem
Conventional autofocus systems in microscopy face limitations such as restricted application range, slow response time, and mechanical adjustments, which are costly and complex, especially when dealing with biological samples or non-biological materials under microscopic control.
Innovation Solution
An autofocus device utilizing an electrically tunable lens (ETL) coupled with a monitoring beam source and detector, enabling feedback-controlled focal position adjustment without mechanical lens translations, using a feedback loop to adjust the ETL based on detected objective distance variations and calibration data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If image analysis based autofocus systems are used to detect focal position drift, then the focal position can be adjusted to compensate for drift, but the system cannot be applied with microscopy modes that do not collect images continuously and has slow response time due to time-consuming image analysis
Solution Approach 1:
The patent replaces mechanical image analysis with an optical monitoring beam system. The monitoring beam passes through the imaging system and sample, and its position on a detector directly indicates focal position, eliminating the need for time-consuming image capture and analysis while enabling continuous autofocus control in all microscopy modes
Solution Approach 2:
The patent introduces a monitoring beam as an intermediary to detect focal position drift. The beam's position on the detector serves as a direct indicator of focus status, providing real-time feedback without requiring image analysis, thus resolving the contradiction between measurement precision and response speed
2Measurement precision
If mechanical objective actuators are used to adjust the microscope objective to maintain focus, then the focal position can be corrected, but the system becomes mechanically complex and costly
Solution Approach 1:
The patent replaces mechanical objective actuators with an electrically tunable lens (ETL) that adjusts focal position through electrical control of lens curvature. The ETL is optically coupled to the microscope objective and modifies the effective focal distance electrically, eliminating complex mechanical translation systems while maintaining precise focal control
Solution Approach 2:
The patent changes the control parameter from mechanical position to electrical voltage. The ETL's focal length is adjusted by changing the voltage applied to its deformable membrane, which changes the lens curvature. This parameter change from mechanical to electrical control simplifies the system while maintaining precision
3Reliability
If conventional autofocus systems with mechanical lens translations are used, then focus can be maintained, but the system is costly and complex
Solution Approach 1:
The patent replaces mechanical lens translation with an electrically tunable lens that maintains focus by electrically adjusting lens power. The ETL compensates for focal drift through voltage-controlled curvature changes, providing reliable focus maintenance without mechanical moving parts
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 solution provides a fast, cost-effective, and reliable all-optical autofocus system capable of maintaining focus without mechanical movements, suitable for various microscopy modes and sample types, with improved precision and extended application range.
Implementation Method 1
a monitoring beam source (110) arranged for creating a monitoring beam (111) and for directing the monitoring beam (111) via the imaging system (220) to the sample (1) and back from the sample (1) via the imaging system (220) to a detector device (120)
Implementation Method 2
an electrically tunable lens (ETL) being configured for coupling with the microscope objective (221), wherein the focal position of the imaging system (220) can be set by adjusting the ETL (140)
Data Source
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AI summary
A microscope-autofocus device (100) for feedback-controlling a focal position of an imaging system (220) of a microscope apparatus (200), wherein the imaging system (220) includes a microscope objective (221), comprises a monitoring beam source (110) for creating a monitoring beam (111), a detector device (120) for detecting a drift variation of an axial objective distance between the microscope objective (221) and a sample (1) by sensing the monitoring beam (111) directed through the imaging system (220) to the sample (1) and reflected by the sample (1), and a feedback loop device (130) for controlling the imaging system (220) in dependency on the detected objective distance variation of the microscope objective (221), wherein the microscope-autofocus device(100) includes an electrically tunable lens (140) being configured to be coupled with the microscope objective (221) and being capable of adjusting the focal position of the imaging system (220) by varying a lens control input of the electrically tunable lens (140), and the feedback loop device (130)is arranged for controlling the focal position of the imaging system (220) by controlling the lens control input of the electrically tunable lens (140) on the basis of a varying set-point value being determined by actual values of the detected objective distance variation and the lens control input and by calibration data assigning detector device output values to objective distance variation values and lens control input values,wherein the calibration data are stored in a calibration data storage coupled with the feedback loop device(130). Furthermore, a microscope apparatus (200) including the microscope-autofocus device (100), an autofocus-control method for operating the microscope apparatus and a microscopy method are described..