Microscopic Transmitted-Light Contrast Using Asymmetric Pupils
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Solution Overview
Problem
Existing microscopic transmitted-light contrasting methods face challenges such as sample-induced pupil aberrations, polarization-induced birefringence, and the need for coherent light sources, which limit their applicability and efficiency, especially in compound microscopes with interchangeable objectives.
Innovation Solution
A method using asymmetric illumination and detection pupils rotated relative to each other, allowing partial overlap in angular space, enabling simultaneous acquisition of bright-field and dark-field components, and reconstructing a complex transmission function to generate high-contrast images without requiring full illumination of the objective pupil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complete illumination of the objective pupil is used to avoid phase transfer function issues, then image quality improves, but device complexity and cost increase significantly
Solution Approach 1:
The illumination pupil is segmented into multiple discrete regions (first and second illumination pupils) that can be independently controlled. This segmentation allows selective illumination of specific angular spaces without requiring complete pupil illumination, thereby maintaining image quality while reducing system complexity and cost.
Solution Approach 2:
Instead of completely illuminating the objective pupil, the invention uses partial illumination with asymmetric pupils that cover only the necessary angular spaces. This partial action approach avoids the need for complex illumination systems while still achieving the required image quality by strategically illuminating only the relevant portions of the sample.
2Loss of information
If sequential image acquisition at different defoci is used for transport-of-intensity imaging, then phase information is obtained, but image acquisition rate decreases and artifacts may occur
Solution Approach 1:
The invention employs periodic switching between different asymmetric illumination configurations (first and second illumination pupils) to capture multiple images. This periodic action allows phase information to be extracted through computational processing of sequentially acquired images, maintaining acceptable acquisition rates while avoiding the artifacts associated with continuous focusing changes.
Solution Approach 2:
The invention replaces the mechanical focusing system (changing defoci continuously) with an optical modulation system that switches between discrete asymmetric illumination pupils. This substitution uses optical switching instead of mechanical focusing, thereby maintaining higher image acquisition rates while still enabling phase information recovery through computational methods.
3Productivity
If asymmetric illumination pupils are used for partial overlap in angular space, then bright-field and dark-field components are simultaneously acquired, but pupil alignment precision is challenged
Solution Approach 1:
The invention deliberately uses asymmetric illumination pupils with specific rotational orientations relative to each other. This asymmetry creates distinct angular space coverage patterns that enable simultaneous acquisition of both bright-field and dark-field components. The asymmetric design, while challenging alignment, provides robust contrast mechanisms that are less sensitive to minor misalignments compared to symmetric configurations.
Solution Approach 2:
The invention changes the orientation parameter of the illumination pupils relative to each other (rotational angle) to optimize the overlap in angular space. By adjusting this parameter, the system achieves the desired balance between bright-field and dark-field component acquisition while managing alignment requirements through computational optimization.
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 high-contrast imaging across the full magnification and aperture range of a compound microscope, utilizing incoherent light sources, and allowing dynamic samples to be imaged without artifacts, while maintaining resolution and cost-effectiveness.
Implementation Method 1
These two partial beams are superimposed and interfered with on the objective side by another Wollaston prism
Implementation Method 2
the illuminating light is split by a Wollaston prism into two coherent partial beams that are laterally offset from one another in the sample
Implementation Method 3
This polarization-induced splitting of the two partial beams in the DIC method results in birefringence
Data Source
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AI summary
A microscopic transmitted light contrasting method is disclosed, in which a sample (16) is illuminated, at least in part, by an asymmetric first illumination pupil (38), the sample (16) is imaged, at least in part, by an asymmetric first detection pupil (40) in order to produce a first partial image (54a), the first illumination pupil (38) and the first detection pupil (40) being twisted and disposed relative to one another with partial overlap in a projection on a plane that is located perpendicular to an optical axis, in such a way that at least one first region of the angular space is located in a bright field and a second region of the angular space, which differs from the first region, is located in a dark field, and the first partial image (54a) has a first bright field component and a first dark field component, the sample (16) is illuminated, at least in part, by an asymmetric second illumination pupil, the sample (16) is imaged, at least in part, by an asymmetric second detection pupil in order to produce a second partial image (54b), the second illumination pupil and the second detection pupil being twisted and disposed relative to one another with partial overlap in a projection on the plane that is located perpendicular to the optical axis, in such a way that at least one third region of the angular space is located in a bright field and a fourth region of the angular space, which differs from the third region, is located in a dark field, and the second partial image has a second bright field component and a second dark field component, and an image of the sample is produced from the first partial image (54a) and the second partial image (54b).