Line-field OCT K-space Calibration via Resampling
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Solution Overview
Problem
Swept source optical coherence tomography (SS-OCT) systems face challenges in achieving linear wavelength tuning due to non-linearities in the swept laser source, leading to distortions and artifacts in the reconstructed images.
Innovation Solution
The system employs a line-field sensor to track the sweep linearity of the swept laser source, using a frequency reference to monitor the instantaneous wavenumber and calculate a resampling curve to achieve k-linearization, thereby correcting non-linearities in the wavelength tuning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a swept laser source is used to achieve high imaging speed in SS-OCT, then imaging speed is improved, but non-linear wavelength tuning occurs causing distortions and artifacts in reconstructed images
Solution Approach 1:
The system performs k-linearization by resampling the spectral data before Fourier transformation to correct non-linear wavelength tuning. A calibration process is executed beforehand to determine the relationship between detector pixel positions and wavenumber, creating a mapping function that pre-compensates for non-linearities in subsequent imaging operations
Solution Approach 2:
The system uses a frequency reference (such as an etalon or atomic fountain) to monitor the instantaneous wavenumber during laser sweeping. The detected reference signal provides feedback to verify and correct the wavelength tuning linearity, ensuring accurate k-space sampling throughout the imaging process
2Productivity
If spectral data is not evenly distributed in wavenumber space, then Fourier transform reconstruction can be performed, but axial resolution decreases and artifacts appear in the image
Solution Approach 1:
The system transforms the spectral data from non-uniform pixel space to uniform wavenumber space through resampling. By changing the sampling parameter distribution to be evenly spaced in k-space, the Fourier transform achieves optimal axial resolution without artifacts while maintaining reconstruction capability
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 improves the axial resolution and image quality of SS-OCT systems by ensuring that the spectral data is evenly distributed in wavenumber space, reducing artifacts and enhancing the accuracy of depth measurements.
Implementation Method 1
Optical coherence tomography (OCT) is a cross-sectional, non-invasive imaging modality
Implementation Method 2
The spectral information discrimination in FD-OCT is accomplished either by using a dispersive spectrometer in the detection arm (spectral domain or SD-OCT) or rapidly scanning swept laser source (swept-source OCT or SS-OCT)
Implementation Method 3
A line-field sensor, arranged to receive interference signals corresponding to light scattered from a sample and reference light
Implementation Method 4
using a frequency reference to monitor the instantaneous wavenumber and calculate a resampling curve to achieve k-linearization
Data Source
AI summary
A line-field optical coherence tomography (OCT) system and method provide enhanced imaging accuracy through k-linearization of interference data. The system includes a swept laser source, a line-field sensor, and a single board computer (SBC) with processing capabilities. The system uses a frequency reference to produce a periodic reference pattern, which is detected by a subset of pixels in the line-field sensor. The SBC determines a resampling curve based on the reference pattern to correct non-linearities in the wavelength tuning of the laser. The resampling curve is applied to k-linearize the interference data, enabling the generation of high resolution transform-limited depth profiles through inverse Fourier transform. Methods are disclosed for recalculating the resampling curve periodically, continuously, or adaptively based on a linearity threshold. The system can further update the laser's tuning function dynamically to ensure consistent performance. These advancements enable precise and efficient OCT imaging for applications such as ophthalmology, angiography, and other diagnostic uses.