Meso-Optical Elements for High Rayleigh Length Light Sheets
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Solution Overview
Problem
Conventional light sheet microscopy and STED microscopy face limitations due to low Rayleigh lengths of Gaussian beams, leading to broadened optical sections and reduced resolution, especially when using Gaussian beams for two-photon excitation in near-infrared ranges.
Innovation Solution
The use of interconnected meso-optical elements, such as Powell lenses or Axicons, in conjunction with a phase-shifting element like an aspherical lens, generates non-Gaussian beams that eliminate secondary maxima through interference, resulting in high Rayleigh length light sheets or beams with a flattened transverse intensity profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional Gaussian beams are used for light sheet microscopy, then the setup is simple and easy to implement, but the Rayleigh length is short causing the light sheet to broaden quickly and reducing resolution
Solution Approach 1:
The patent changes the beam parameter from Gaussian to non-Gaussian (Bessel-like) beams by introducing meso-optical elements (axicons or Powell lenses). This transformation fundamentally alters the beam's propagation characteristics, enabling a long Rayleigh length and maintaining a thin light sheet profile over extended distances, thereby achieving high axial resolution without sacrificing ease of implementation.
Solution Approach 2:
The patent employs a composite optical system combining meso-optical elements (axicons or Powell lenses) with conventional optical components. This composite approach integrates the beam-shaping capabilities of specialized optical elements with standard microscopy components, achieving both long Rayleigh length and practical ease of operation in a unified system.
2Measurement precision
If Bessel beams are used to achieve long Rayleigh length, then the axial resolution is improved, but secondary maxima in the form of coaxial rings generate disturbing background
Solution Approach 1:
The patent extracts and eliminates the harmful secondary maxima from the Bessel beam profile while retaining the useful long Rayleigh length characteristic. By using two meso-optical elements with specific geometric parameters, the system suppresses the formation of intense coaxial rings that cause disturbing background, thereby improving optical sectioning quality without sacrificing axial resolution.
Solution Approach 2:
The patent converts the potentially harmful secondary maxima into a beneficial pattern by carefully controlling their interference. The two meso-optical elements are configured so that secondary maxima from each element interfere destructively with each other, eliminating the disturbing background while the central maximum is reinforced constructively, transforming a harmful effect into a useful feature for high-resolution imaging.
3Length of stationary object
If a single meso-optical element is used to generate non-Gaussian beams, then the Rayleigh length is increased, but secondary maxima are generated that broaden the effective thickness
Solution Approach 1:
The patent merges the beam profiles generated by two meso-optical elements in such a way that the secondary maxima from each element overlap and eliminate each other through destructive interference. The central beams overlap constructively, reinforcing the main maximum. This merging approach produces a single beam with high Rayleigh length and a clean intensity profile free from disturbing secondary maxima.
4Ease of operation
If Gaussian beams are used for two-photon excitation in near-infrared range, then the setup is straightforward, but the focus length is very small making it impracticable for large specimens
Solution Approach 1:
The patent changes the beam parameter from Gaussian to non-Gaussian (Bessel-like) beams by introducing meso-optical elements. This fundamental parameter change transforms the beam's propagation characteristics, extending the effective focus length from millimeters to centimeters or meters, making two-photon excitation practical for large specimens while maintaining the straightforward setup of conventional optics.
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 approach enables the generation of thin, high Rayleigh length light sheets or beams, enhancing resolution in light sheet microscopy and allowing for the combination of STED and light sheet microscopy, while maintaining a focused excitation cross-section even at distances from the focus, reducing scattering effects in large or scattering specimens.
Implementation Method 1
the non-Gaussian beams generated by the meso-optical elements overlap in such a way that the disturbing secondary maxima disappear through interference
Implementation Method 2
the disturbing secondary maxima, as a result of a phase shift, can overlap destructively and thus be eliminated. The central beams overlap constructively
Implementation Method 3
in particular one phase-shifting element, especially an aspherical lens, placed there between prevents the generation in the beam path of beam enlarging secondary maxima
Implementation Method 4
the transparent fluorescent preparation is irradiated from the side with a thin light sheet, whereby an 'optical section' is generated. The optical section results from the optical excitation of the fluorescence specifically in the plane of the light sheet
Data Source
AI summary
The present application relates to devices and methods for generating light sheets and thin light beams with high Rayleigh lengths by using at least two interconnected meso-optical elements.