Bessel Optics Light Sheet Microscope Axial Resolution
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Solution Overview
Problem
Existing Selective Plane Illumination Microscopy (SPIM) technologies face limitations in achieving high axial resolution and large image field size due to the generation of light sheets with beam divergence, and suffer from shadowing issues caused by uneven illumination, which complicates the setup and increases costs.
Innovation Solution
The use of Bessel optics to generate a light sheet by interfering at least two plane waves with acute angles, producing a light sheet with increased depth of field and reduced shadowing, eliminating the need for multiple light sources or complex illumination arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light sheet is generated at the focus of a cylindrical lens, then axial resolution is improved, but the observable image field size is limited due to beam divergence
Solution Approach 1:
The light sheet is segmented into multiple plane waves that are spatially separated and then recombined. The illumination beam is divided into at least two plane waves with different propagation directions, which are then superimposed to form an extended light sheet with improved depth of field and reduced beam divergence.
Solution Approach 2:
The invention extends the light sheet in the illumination direction (X-axis) by introducing a temporal dimension through the superposition of plane waves with different propagation angles. This creates an extended region of constructive interference that increases the usable depth of field without compromising axial resolution.
2Measurement precision
If a rigid light sheet with fixed thickness is used, then axial resolution is maintained, but shadowing occurs in regions with high absorption or scattering
Solution Approach 1:
The light sheet becomes dynamic in nature through the superposition of multiple plane waves with different propagation directions. This creates a flexible illumination pattern that can adapt to sample characteristics, reducing shadowing effects while maintaining axial resolution through constructive interference in the focal plane.
Solution Approach 2:
The invention changes the parameter of light sheet thickness along the illumination direction by superimposing plane waves with different propagation angles. This creates a variable depth of field that extends the usable range and reduces shadowing while maintaining axial resolution in the focal plane.
3Illumination intensity
If multiple light sources or moving optical elements are used to reduce shadowing, then illumination uniformity is improved, but device complexity increases
Solution Approach 1:
Multiple plane waves with different propagation directions are merged into a single illumination path through constructive interference. This combines the benefits of multi-directional illumination (reduced shadowing) with a simple single-source setup, avoiding the complexity of multiple light sources or moving optical elements.
Solution Approach 2:
The invention introduces an intermediary optical system that transforms a single light beam into multiple plane waves with different propagation directions. This intermediary transformation enables multi-directional illumination effects without requiring multiple light sources or complex moving parts.
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 enhances the depth of focus and reduces shadowing, allowing for a larger usable image field with improved brightness and simplified setup, overcoming the limitations of conventional SPIM technologies.
Implementation Method 1
the plane waves interfere constructively in the focal plane, thereby producing a sheet of light
Implementation Method 2
Bessel optics to generate a light sheet by interfering at least two plane waves
Data Source
Figure 1~2b
Figure 3a~4
AI summary
The invention relates to a microscope comprising an imaging objective (4) for imaging a sample (3) onto a detector and means for illuminating the sample (3) with a light sheet (7) in the focal plane of the imaging objective (4), comprising a coherent light-emitting illumination source (1). In such a microscope, the illumination means comprise a Bessel optic which generates at least two plane waves (6) from the light beam (5) and defines propagation directions for the plane waves (6), wherein the propagation direction of each of the plane waves (6) forms an acute angle with the focal plane, the magnitude of which is the same for each of the plane waves (6), so that the plane waves (6) constructively interfere in the focal plane, thereby generating a light sheet (7).