SPIM Microscope Sinc Filter Light Sheet Design
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Solution Overview
Problem
Existing SPIM microscopes face challenges in achieving a light sheet with minimal expansion in one direction while maintaining wide expansion in the other directions, and current solutions result in excessive light outside the desired plane, potentially damaging specimens.
Innovation Solution
The use of sinc(z) and Mathieu beams, filtered with sinc(z) and sinc(vy) functions, to create an expansion-invariant light distribution, limiting the z component's frequency spectrum and achieving a constant beam profile across a larger area, allowing for larger light sheet expansions with reduced light outside the desired plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If conventional illuminating optical units with cylinder lenses are used, then a light sheet can be generated, but the light sheet has excessive expansion in the y direction with high luminous power above and below the desired plane
Solution Approach 1:
The patent transforms the filter function from the z direction to the y direction using a coordinate transformation. Specifically, a sinc(z) filter function is converted to sinc(vy) where vy = y*cos(α) + z*sin(α), effectively changing the spatial frequency parameters to achieve the desired light sheet profile with reduced expansion in the y direction.
Solution Approach 2:
The patent introduces a complex filter as an intermediary element in the illuminating optical unit. This filter, positioned in a plane perpendicular to the optical axis, modifies the light distribution by applying a transformed sinc function, thereby controlling the light sheet's expansion and reducing unwanted luminous power above and below the desired plane.
2Area of stationary object
If the light sheet expansion in x and z directions is increased, then wider illumination area is achieved, but light intensity outside the desired plane increases causing specimen damage
Solution Approach 1:
The patent applies a coordinate transformation to the filter function parameters, converting from z-direction filtering to y-direction filtering. This parameter change allows the light sheet to maintain wide lateral expansion in x and z directions while simultaneously confining the light intensity in the y direction, preventing specimen damage from out-of-plane light.
3Measurement precision
If a thin light sheet is generated with minimal y-direction expansion, then measurement precision from observation direction is improved, but the light sheet cannot maintain wide expansion in x and z directions
Solution Approach 1:
The patent transforms the filter function from limiting expansion in the z direction to limiting expansion in the y direction through coordinate transformation. This allows the light sheet to achieve thin profile (minimal expansion) in the y direction for improved measurement precision, while simultaneously maintaining wide expansion in the x and z directions for adequate illumination area.
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 light sheets with larger lateral expansions and smaller thickness in one direction, reducing light intensity outside the sheet by at least a factor of 10 compared to previous methods, while maintaining high resolution and minimizing specimen damage.
Implementation Method 1
The illumination means is an illuminating source that emits coherent light
Implementation Method 2
the specimen is illuminated with a light sheet in the focal plane of the imaging objective
Implementation Method 3
an image of said plane of the specimen is obtained in the form of an optical section using an imaging optical unit
Data Source
AI summary
A microscope, in particular according to any of the preceding claims, consisting of an illuminating device, comprising an illumination light source and an illumination beam path for illuminating the specimen with a light sheet, a detection device for detecting light emitted by the specimen, and an imaging optical unit, which images the specimen via an imaging objective in an imaging beam path at least partly onto the detection device, wherein the light sheet is essentially planar at the focus of the imaging objective or in a defined plane in proximity of the geometrical focus of the imaging objective, and wherein the imaging objective has an optical axis, which intersects the plane of the light sheet at an angle that is different from zero, preferably perpendicularly, wherein an amplitude and/or phase filter is provided in the illumination beam path, said filter acting as a sine spatial filter in that it limits the illumination light in at least one spatial direction by filtering the spatial frequencies that occur with a sine function and/or in that the illumination light is limited with regard to the phase and amplitude thereof in at least one spatial direction by a sine filter function, and/or a combined amplitude and phase filter is provided in the illumination beam path, said filter shaping the light sheet by influencing the transmission profile of the illumination light distribution with a sine filter function.