Bivortex Phase Mask for Hybrid STED Axial Resolution
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Solution Overview
Problem
Conventional STED microscopy techniques require multiple phase masks for hybrid operation, leading to alignment issues and compromised resolution and signal quality due to misalignments and aberrations, with 2D and 3D modes lacking isotropic shrinkage of the fluorescent source.
Innovation Solution
A single phase mask with a bivortex mathematical function is used to generate a coherent hybrid STED (CH-STED) mode, providing improved axial performance and resolution without the need for multiple masks, through a phase plate or spatial light modulator device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple phase masks are used for hybrid STED operation, then isotropic shrinkage of fluorescent source is improved, but alignment precision and resolution deteriorate due to misalignments and aberrations
Solution Approach 1:
The patent combines the functions of multiple phase masks into a single phase mask with a bivortex profile. This single mask integrates both 2D and 3D depletion capabilities, eliminating the need for separate masks and their associated alignment issues. The bivortex profile is mathematically designed to produce the desired hybrid depletion pattern that achieves isotropic shrinkage while maintaining precise alignment through a single optical element.
2Manufacturing precision
If conventional 2D STED mode is used, then lateral resolution is improved, but axial resolution and optical sectioning deteriorate
Solution Approach 1:
The patent extends the conventional 2D STED approach by introducing a bivortex phase profile that adds axial depletion capability. The mathematical function incorporates both radial and azimuthal phase variations, creating a three-dimensional depletion pattern that simultaneously improves lateral and axial resolution. This dimensional extension transforms the 2D depletion pattern into a 3D pattern with superior isotropic resolution.
3Measurement precision
If conventional 3D STED mode is used, then axial resolution is improved, but lateral resolution and signal efficiency deteriorate
Solution Approach 1:
The bivortex phase mask implements local quality by creating different depletion characteristics in different spatial regions. The phase function is designed to provide strong radial depletion for lateral resolution improvement while simultaneously providing axial depletion for axial resolution enhancement. Each region of the phase mask contributes differently to the overall depletion pattern, optimizing both lateral and axial performance locally and globally.
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
CH-STED achieves more isotropic shrinkage of the fluorescent source, enhancing resolution and signal level while minimizing alignment complexities, and improving optical sectioning performance.
Implementation Method 1
The phase plate or spatial light modulator device comprises a bi vortex profile resulting from the imprinting of a bivortex mathematical function on a single phase mask
Implementation Method 2
This depletion is achieved by the process of stimulated emission and is usually implemented by hitting the sample with a so-called 'STED beam'
Implementation Method 3
Conventional 2D STED uses a helical ramp phase mask to create a doughnut-shaped beam featuring an intensity null along the optical axis with a higher intensity ring around this axis
Implementation Method 4
Only the central part of the excited spot will survive the action of the STED depletion beam and thus eventually fluoresce
Data Source
Figure 1a~2
Figure 3~4c
AI summary
The present invention is concerned with a single phase mask comprising a bivortex pattern for use in STED or RESOLFT microscopy. The phase mask is generated either by using a phase plate or an SLM. The bivortex pattern allows some freedom in shaping the STED beam to improve the microscope's axial performance and optical sectioning capacity. The disclosed phase masks and methods of STED and RESOLFT microscopy may advantageously be applied to provide a hybrid 2D/3D STED regime but one with a significant reduction in the degrees of freedom for alignment relative to what is found in incoherent beam superpositions, thus providing an improvement in beam quality, namely a minimized central intensity and lower sensitivity to aberrations, resulting in an increased signal level and axial performance.