Light Microscope Depth Resolution via Tapered Illumination
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Solution Overview
Problem
Conventional light microscopes are limited in their ability to utilize all available information from the specimen, as they typically filter out non-confocal portions of the specimen light, restricting the acquisition of both confocal and wide-field images and requiring mechanical movements for scanning.
Innovation Solution
A light microscope design that allows the detection of both confocal and non-confocal portions of the specimen light using a structured element and a beam splitter, enabling the creation of wide-field images without mechanical scanning, and utilizing longitudinal chromatic aberration for depth resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If confocal microscopy is used to achieve depth resolution and topography measurement, then measurement precision is improved, but the system requires complex mechanical scanning in z-direction and highly accurate mechanical adjusting elements
Solution Approach 1:
The patent replaces mechanical z-scanning with optical sectioning using a tapered illumination beam. The beam is focused to a small spot at a specific depth and gradually expanded to illuminate deeper regions, eliminating the need for mechanical movement in the z-direction while maintaining depth resolution through optical means.
Solution Approach 2:
The patent changes the illumination parameters by using a tapered beam that varies in cross-section along the propagation direction. The beam is focused to a minimum spot size at a reference depth and then expanded, creating different illumination cones at different depths. This parameter change enables depth-selective imaging without mechanical scanning.
2Loss of information
If x-y scanning is performed to achieve complete specimen coverage, then information content is improved, but measurement time is increased
Solution Approach 1:
The patent performs preliminary wide-field imaging to capture the entire specimen area in a single exposure, obtaining overview information and identifying regions of interest. This preliminary action reduces the need for extensive subsequent scanning, as the main structural information is already captured.
Solution Approach 2:
The patent segments the imaging process into two stages: a wide-field overview scan to capture all specimen regions, and then selective confocal scanning only of identified regions of interest. This segmentation reduces total measurement time by avoiding redundant scanning of areas that do not require high-resolution confocal imaging.
3Measurement precision
If mechanical adjusting elements with high accuracy are used to improve height measurement precision, then measurement precision is improved, but device complexity and cost are increased
Solution Approach 1:
The patent replaces mechanical z-position adjustment with optical focusing. The height measurement is achieved by detecting the focal position of the tapered illumination beam through image analysis, eliminating the need for precision mechanical stages and piezo actuators while maintaining measurement accuracy.
Solution Approach 2:
The patent introduces image processing algorithms as an intermediary between the optical system and height measurement. The focal position is determined by analyzing image sharpness and contrast variations, using computational methods to achieve precise height measurement without direct mechanical positioning.
4Measurement precision
If structured illumination is used to produce confocal cross-sectional images, then depth resolution is improved, but the system requires fixed elements with defined pixel size or hole size limiting flexibility
Solution Approach 1:
The patent uses a dynamically adjustable tapered illumination beam instead of fixed structured illumination elements. The beam waist position and size can be varied continuously by changing the focus position and aperture settings, allowing adaptation to different field of view sizes and depths without requiring physical replacement of fixed components like Nipkow discs or microlens arrays.
Solution Approach 2:
The tapered illumination beam system serves multiple functions: it can be focused to different depths, adjusted to different spot sizes, and repositioned along the optical axis. This single optical element replaces multiple fixed components, providing universal applicability across different imaging conditions and specimen types.
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 the acquisition of a large information content, including both confocal and wide-field images, with reduced or eliminated mechanical movements, improving measurement efficiency and resolution without the need for mechanical adjustments.
Implementation Method 1
a beam splitter to separate specimen light into a confocal portion and a non-confocal portion
Implementation Method 2
focussing means to focus illuminating light onto the specimen, wherein the focussing means have a longitudinal chromatic aberration to produce a depth resolution
Data Source
AI summary
The invention relates to a light microscope comprising a polychromatic light source for emitting illumination light in the direction of a sample, focussing means for focussing illumination light onto the sample, wherein the focussing means, for generating a depth resolution, have a longitudinal chromatic aberration, and a detection device, which comprises a two-dimensional array of detector elements, for detecting sample light coming from the sample. According to the invention, the light microscope is characterized in that, for detecting both confocal portions and non-confocal portions of the sample light, a beam path from the sample to the detection device is free of elements for completely masking out non-confocal portions. In addition, the invention relates to a method for image recording using a light microscope.