Tailored Spatial Coherence iSCAT Microscopy Speckle Suppression
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Solution Overview
Problem
Conventional interferometric scattering microscopy (iSCAT) techniques face challenges in suppressing speckle-like backgrounds, limiting field of view, and achieving high-speed, high-resolution imaging of complex samples such as biological cells.
Innovation Solution
The method employs a tailored spatial coherence (TSC-iSCAT) by using a rotating diffuser mask and adjustable iris to control the spatial coherence of illumination, reducing speckle interference and enhancing imaging resolution and speed while maintaining sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional iSCAT microscopy is used, then imaging sensitivity is achieved, but speckle-like background interference occurs
Solution Approach 1:
A rotating diffuser mask is introduced as an intermediary component in the illumination path. This diffuser mask randomizes the phase of illumination light, acting as a mediator that transforms coherent laser light into partially coherent light, thereby suppressing speckle interference while preserving imaging sensitivity
Solution Approach 2:
The spatial coherence parameter of the illumination light is dynamically changed by rotating the diffuser mask. By controlling the rotation speed and position of the diffuser, the degree of spatial coherence is adjusted, enabling suppression of speckle backgrounds while maintaining the interferometric contrast needed for sensitive detection
2Productivity
If wide-field illumination is used, then imaging speed is improved, but field of view is limited
Solution Approach 1:
The system employs dynamic illumination by rotating the diffuser mask during wide-field scanning. This dynamic approach allows the illumination beam to rapidly sweep across a large field of view while maintaining high temporal resolution, effectively decoupling the field of view size from imaging speed limitations
3Measurement precision
If coherent illumination is used, then imaging resolution is improved, but speckle interference increases
Solution Approach 1:
Instead of using fully coherent or fully incoherent illumination, the system employs partially coherent illumination by adjusting the diffuser mask parameters. This partial coherence provides sufficient interferometric contrast for high-resolution imaging while simultaneously suppressing speckle interference that would occur with fully coherent light
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
TSC-iSCAT achieves speckle-free imaging with high throughput and diffraction-limited resolution, enabling high-speed, large-field-of-view imaging of biological samples with improved axial resolution and dynamic tracking capabilities.
Implementation Method 1
The method employs a tailored spatial coherence (TSC-iSCAT) by using a rotating diffuser mask and adjustable iris to control the spatial coherence of illumination
Implementation Method 2
reducing speckle interference and enhancing imaging resolution and speed
Implementation Method 3
a beam splitting device, a sample receptacle and a detector device
Implementation Method 4
interferometric scattering (iSCAT) microscopy
Implementation Method 5
Interferometric Scattering Microscopy: Seeing Single Nanoparticles and Molecules via Rayleigh Scattering
Data Source
Figure 1~2
Figure 3A~3F
Figure 4A~4D
AI summary
An interferometric scattering microscopy (iSCAT) apparatus 100 for iSCAT-based imaging a sample under investigation, for obtaining a sample image, comprises an optical imaging system with an illumination device 10, an optical relaying device 20 including a beam splitting device 21, a sample receptacle 30 and a detector device 40. The illumination device 10 includes a laser source device 11 being arranged for creating illumination light 2. The optical relaying device 20 is arranged between the laser device 11 and the sample receptacle 30 for relaying the illumination light 2 to the sample receptacle 30. The beam splitting device 21 is arranged for deflecting a first portion 2A of the illumination light 2 towards the sample receptacle 30, deflecting a second portion 2B of the illumination light 2 towards the detector device 40 and for superimposing scattering light 2C scattered at a sample 1 arranged at the sample receptacle 30 with the second portion 2B of the illumination light 2. The detector device 40 is arranged for receiving the superimposed scattering light 2C and second portion 2B of the illumination light 2 in an image plane of the optical imaging system. A coherence setting device 50 is arranged for targeted setting a point spread function of the optical imaging system in the image plane by applying and controlling a spatial degree of coherence of the illumination light 2 output by the laser source device 11. Furthermore, a method of iSCAT microscopy, including iSCAT-based imaging a sample 1, in particular including bioparticles, like protein particles and/or protein molecules, is described, wherein the iSCAT apparatus 100 is employed.