Direct SIM Reconstruction Bypassing Frequency Domain Artifacts
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Solution Overview
Problem
Conventional super-resolution microscopy techniques, such as STED and SMLM, are unsuitable for imaging living cells due to high illumination intensity and low temporal resolution, while SIM is prone to artifacts from non-uniform parameters, affecting the quality of super-resolution images.
Innovation Solution
The direct structured illumination microscopy (dSIM) reconstruction method uses structured light with multiple modulation directions and phases to extract high-frequency information, converting incoherent signals into coherent signals through wavelet packet filtering and autocorrelation, bypassing complex frequency domain operations to prevent artifacts and achieve doubled spatial resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SIM method is used to achieve super-resolution imaging, then spatial resolution is improved, but artifacts are generated due to non-uniform parameters affecting image quality
Solution Approach 1:
The patent applies local quality by transitioning from uniform global reconstruction parameters to local adaptive parameters. The system divides the field of view into multiple regions and determines reconstruction parameters (fringe direction, phase, modulation depth) independently for each local region based on actual measured values, rather than applying uniform parameters across the entire field of view. This local adaptation eliminates artifacts caused by parameter non-uniformity while maintaining super-resolution capability.
2Measurement precision
If STED or SMLM is used to achieve high spatial resolution, then measurement precision is improved, but illumination intensity increases and temporal resolution decreases
Solution Approach 1:
The patent changes the illumination parameter regime by using structured illumination with much lower intensity compared to STED or SMLM. Instead of using high-intensity depletion beams (STED) or intense excitation for single-molecule localization (SMLM), the system employs moderate-intensity structured light patterns that enable super-resolution through spatial frequency separation, thereby reducing photodamage and enabling live-cell imaging.
3Productivity
If conventional SIM is used for fast imaging of living cells, then temporal resolution is improved, but artifacts are generated due to parameter sensitivity
Solution Approach 1:
The patent implements feedback by measuring actual reconstruction parameters (fringe direction, phase, modulation depth) in each local region and using these measured values to guide the reconstruction process. This closed-loop approach compensates for parameter variations and eliminates artifacts, maintaining both fast imaging capability and high image quality for live-cell applications.
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
dSIM provides high temporal resolution, multicolor imaging, and reduced artifacts, maintaining image quality and adaptability for live cell imaging, with improved spatial resolution and resistance to parameter errors.
Implementation Method 1
Structured illumination can make high-frequency information of the sample generate frequency shifts and enter an observable optical transfer function (OTF), and make the high-frequency information be moved to a correct position in a frequency domain
Implementation Method 2
for each 3D original image in the original image stack, extracting a first modulation frequency K1, a second modulation frequency K2, and a zero frequency K0 of each pixel by using a wavelet packet frequency separation method
Implementation Method 3
performing interpolation on each image in the first extracted image stack and the second extracted image stack through spatial frequency domain fast Fourier transform (FFT) zero padding to increase a sampling frequency
Implementation Method 4
performing deconvolution on each denoised extracted image in the first and second denoised extracted image stacks through a Richardson-Lucy (RL) algorithm to improve a relative strength of a high-frequency signal
Data Source
AI summary
A direct structured illumination microscopy (dSIM) reconstruction method is provided. First, a time domain modulation signal is extracted through a wavelet. Then, an incoherent signal is converted into a coherent signal. Next, an accumulation amount at each pixel is calculated. Finally, a super-resolution image is generated by using a correlation between signals at different spatial positions. An autocorrelation algorithm of dSIM is insensitive to an error of a reconstruction parameter. dSIM bypasses a complex frequency domain operation in structured illumination microscopy (SIM) image reconstruction, and prevents an artifact caused by the parameter error in the frequency domain operation. The dSIM algorithm has high adaptability and can be used in laboratory SIM, nonlinear SIM imaging systems, or commercial systems.