Decentred Autofocus Aperture Stop for Microscope Triangulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing autofocus systems in microscopy face limitations due to fixed aperture stops, which restrict their ability to handle large defocus and are prone to disruptive first-order reflections, especially when dealing with samples that reflect poorly, such as the interface between cover glass and aqueous solutions.
Innovation Solution
The implementation of a decentred autofocus aperture stop with a diaphragm opening positioned off-center relative to the optical axis, limiting the measuring beam's cross-section and reducing first-order reflections by preventing the beam from passing through the optical axis region, thereby enhancing signal-to-noise ratios and allowing for precise focus adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed aperture stop is used in the autofocus system, then the device structure is simple, but the capture range for focus adjustments is limited and first-order reflections occur
Solution Approach 1:
The patent applies asymmetry by positioning the aperture stop off-center (decentred) relative to the optical axis. This asymmetric placement allows the measuring beam to traverse only a portion of the optical path, avoiding first-order reflections while expanding the capture range for focus adjustments. The aperture stop is located at a distance from the optical axis such that the beam pencil does not pass through the central region where reflections occur.
2Productivity
If the measuring beam passes through the optical axis region, then the beam path is straightforward, but disruptive first-order reflections occur
Solution Approach 1:
The patent extracts or removes the problematic central region from the beam path by positioning the aperture stop off-center. This causes the measuring beam to traverse only the peripheral regions of the optical system, effectively taking out the optical axis region that generates first-order reflections. The result is improved signal-to-noise ratio by eliminating reflective interference.
3Measurement precision
If a decentred aperture stop is used, then first-order reflections are reduced, but the beam cross-section must be precisely limited
Solution Approach 1:
The patent applies local quality by creating a localized beam path that traverses only specific regions of the optical system. The aperture stop is positioned to allow light through only a defined portion of the beam cross-section, ensuring that the measuring beam interacts with specific local regions of the sample while avoiding areas that produce reflections. This localized approach improves focus detection accuracy.
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 larger capture range for focus adjustments, reduces the impact of scattered light, and enables accurate autofocusing on samples with low reflection surfaces, improving the precision and stability of focus holding, even at low reflection levels.
Implementation Method 1
the aperture stop comprises at least one diaphragm opening with which a measuring beam pencil extending in the direction of the optical axis of the autofocusing device can be limited in its cross section
Implementation Method 2
autofocusing optical means, in order to generate a measuring pattern on an object by means of the autofocus measuring beam using an objective of the microscope
Implementation Method 3
The deflected beam 30 is deflected or diffracted by the objective 10 so as to strike the object plane 16 at a reflection point C at a diagonal or sloping angle
Implementation Method 4
The deflected beam 32 then illuminates the detector 28, e.g. a position-sensitive detector (PSD), the output signal of which is dependent on the location where the beam 32 strikes or makes contact, so that the location is determined in this way
Data Source
AI summary
The present invention relates to an autofocus aperture stop (5, 6) in a triangulating autofocusing device (21) for a microscope (40), wherein the autofocus aperture stop (5, 6) comprises at least one diaphragm opening (3, 4) with which a measuring beam pencil (34) used for the autofocusing and running in the direction of the optical axis (18) of the autofocusing device (21) can be limited in its cross section, wherein the diaphragm opening (3, 4) of the autofocus aperture stop (5, 6) is arranged in a decentred position at a spacing from the optical axis (18) of the autofocusing device (21), wherein a decentred autofocus measuring beam (36) can be generated by the diaphragm opening (3, 4) in one half of the cross section (17) of the measuring beam pencil (34).