Dispersion-Compensated Optical Coherence Tomography Signal Processing
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Solution Overview
Problem
Optical coherence tomography (OCT) systems face resolution loss due to dispersion, which blurs boundary surfaces and structures, especially at increasing measuring depths, making it difficult to accurately separate closely adjacent surfaces, and existing dispersion compensation methods are either limited to single depths or require multiple expensive measurements.
Innovation Solution
A device that uses a computer arrangement to detect interference signals, apply dispersion compensation through layer-by-layer phase correction, and perform Fourier transformations to achieve high axial resolution by adapting association instructions for each depth, allowing for section-by-section numeric dispersion compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dispersion compensation is applied for a single predefined depth, then axial resolution is improved at that specific depth, but the method cannot compensate for dispersion at multiple different depths simultaneously
Solution Approach 1:
The patent divides the imaging depth range into multiple depth ranges, with each range requiring separate dispersion compensation. The system processes different depth segments independently, applying appropriate dispersion compensation to each segment to maintain high axial resolution across the entire imaging range.
Solution Approach 2:
The patent implements dynamic dispersion compensation by adjusting compensation parameters according to the specific depth range being processed. The system adapts the dispersion compensation strategy based on the depth position, allowing optimal resolution at each depth rather than using a fixed compensation approach.
2Adaptability or versatility
If multiple separate measurements with changed optical compensation are performed for different depths, then dispersion compensation for multiple depths is achieved, but the inherent accuracy of boundary surface position is lost due to multiple measurements
Solution Approach 1:
The patent performs dispersion compensation calculations in advance for multiple depth ranges before actual imaging. By pre-calculating and storing the appropriate compensation parameters for each depth range, the system can quickly apply the correct compensation during imaging without requiring multiple separate measurements, thus maintaining boundary surface position accuracy.
3Measurement precision
If equivalent optical path lengths are generated by introducing identical media in object arm and reference arm, then dispersion compensation is achieved for a single depth, but the system becomes more complex and cannot adapt to different depths
Solution Approach 1:
The patent replaces complex optical dispersion compensation mechanisms (introducing physical media in optical paths) with digital signal processing methods. The system uses computer arrangements to calculate and apply dispersion compensation to the interferometric signal, eliminating the need for complex optical components while achieving effective dispersion compensation across multiple depth ranges.
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
Enables the detection of boundary surfaces and structures at different depths with high resolution by compensating dispersion specifically for each depth range, resulting in a theoretically highest possible axial resolution in OCT images.
Implementation Method 1
The light scattered back from the object is then superposed by a coherent light beam from a reference arm for obtaining an interference signal
Implementation Method 2
The object reflects or scatters the light of the light beam into different measuring depths
Implementation Method 3
The computer arrangement is designed to determine a plurality of intermediate signals in a spatial frequency range from the interference signal, whereby each of the intermediate signals is dispersion-compensated for a different depth of the object
Implementation Method 4
The computer arrangement is furthermore designed to determine a locally resolved image signal for each of the intermediate signals by applying a Fourier transformation on the particular intermediate signal
Data Source
AI summary
In certain embodiments, a device for optical coherence tomography (OCT) includes a signal detection device and a computer arrangement. The signal detection device is designed to detect an interference signal (G(ω)) for an object to be imaged in an optical frequency range (ω). The computer arrangement is designed to determine intermediate signals (G1(k), G2(k)) in a spatial frequency range (k) from the intermediate interference signal (G(ω)), whereby each of the intermediate signals (G1(k), G2(k)) is dispersion-compensated for a different depth (z1, z2) of the object. A locally resolved image signal (FFT1, FFT2) is determined for each of the intermediate signals (G1(k), G2(k)) by applying a Fourier transformation to the particular intermediate signal (G1(k), G2(k)). A tomography signal (G(z)) is determined from the image signals (FFT1, FFT2).