Microscopic Illumination With Phase-Based Speckle Suppression
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Solution Overview
Problem
Existing methods for microscopic illumination, such as those using spatial light modulators, often result in speckle patterns due to spatial coherence, requiring complex techniques like sequential pattern display or diffusing plates to achieve homogeneous illumination, which are cumbersome.
Innovation Solution
The apparatus and method utilize a phase device in the illumination beam path to partially cancel spatial coherence by decomposing the illumination beam into incoherent component beams, using a single component like a glass plate or stepped glass plate to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a spatial light modulator is used to generate desired illumination patterns, then illumination accuracy is improved, but speckle patterns appear due to spatial coherence
Solution Approach 1:
The laser beam is divided into multiple component beams that propagate in different directions through the use of a diffuser and optical elements. This segmentation of the coherent beam into multiple incoherent components eliminates the speckle patterns while maintaining the desired illumination pattern accuracy through subsequent recombination at the sample plane.
Solution Approach 2:
A diffuser is introduced as an intermediary element in the illumination beam path between the laser and the spatial light modulator. This diffuser destroys the spatial coherence of the laser light, preventing speckle formation, while still allowing the spatial light modulator to shape the illumination pattern accurately.
2Object-generated harmful factors
If sequential display of multiple control patterns is used to suppress speckles, then speckle patterns are reduced, but device complexity and operation time increase
Solution Approach 1:
Instead of sequentially displaying multiple control patterns, the system segments the laser beam into multiple spatial components simultaneously using a diffuser and optical elements. These incoherent components are then recombined to form the desired illumination pattern in a single exposure, eliminating speckles without requiring sequential operation or multiple images.
Solution Approach 2:
The patent employs a stationary diffuser that continuously scatters light in a randomized manner, creating a time-averaged homogeneous illumination pattern. This continuous periodic scattering action suppresses speckles without requiring active modulation or sequential pattern display, simplifying the operation.
3Object-generated harmful factors
If diffusing plates are used to remove bright/dark modulations, then speckle patterns are suppressed, but device complexity increases
Solution Approach 1:
The patent combines the speckle suppression function with the illumination pattern shaping function by integrating a diffuser into the existing spatial light modulator-based illumination system. The diffuser and spatial light modulator work together in a unified optical path, eliminating the need for separate speckle suppression components and reducing overall device complexity.
Solution Approach 2:
A diffuser is positioned as an intermediary element in the illumination beam path, where it destroys spatial coherence to suppress speckles. This single intermediary component achieves speckle reduction without requiring complex optical arrangements or multiple separate devices, simplifying the overall system.
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 achieves accurate and homogeneous illumination with simpler means, reducing the complexity of existing methods and maintaining high resolution without lattice structures.
Implementation Method 1
The optical path length difference between different parts of the glass plate is then dimensioned such that the component laser beams are no longer coherent with one another
Implementation Method 2
Diffusing plates are glass plates with a roughened surface. The unevenness of the surface leads to a small amount of scattering of the transmitted laser light
Data Source
AI summary
The invention relates to an apparatus for microscopic illumination of a sample, having a laser for transmitting illumination light, having an illumination beam path with a microscope objective for guiding the illumination light into a sample plane on or in the sample, the illumination beam path comprising at least one spatial light modulator for manipulating the illumination light, and having a control unit for controlling at least the spatial light modulator. According to the invention, the apparatus is characterized in that the illumination beam path comprises a phase device for at least partial cancellation of a spatial coherence of the illumination light. The invention also relates to a method for microscopic illumination of a sample, a microscope and a microscopy method.