Nano-Sensitive Fourier-Domain OCT System
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Solution Overview
Problem
Current optical coherence tomography (OCT) systems face limitations in achieving nanoscale sensitivity for 3D imaging, particularly in highly scattering media and for structural changes, as they are mostly suited for microscale resolution and are not effective in translating axial spatial frequencies into nano-scale sensitivity.
Innovation Solution
The method involves forming a spectrum of spatial frequencies along the depth direction, calculating local spectra for individual volume elements, translating these spectra into the OCT image domain, and mapping them to provide nano-scale sensitivity, while maintaining micro-scale volume elements, thereby enhancing sensitivity by several orders of magnitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional OCT imaging is used, then microscale structural imaging is achieved, but nanoscale sensitivity is not attained
Solution Approach 1:
The patent transforms axial spatial frequency information (depth dimension) into lateral sensitivity by performing Fourier transformation along the depth direction and mapping the resulting spatial frequency spectra to lateral pixels. This dimensional transformation enables nanoscale sensitivity in the lateral direction using axial scanning data, effectively converting depth-resolution limitations into lateral sensitivity advantages.
Solution Approach 2:
The patent changes the parameter being measured from direct lateral spatial resolution to axial spatial frequency content. By analyzing the spectral content of axial reflections and mapping dominant spatial frequencies to lateral positions, the system achieves nanoscale sensitivity without requiring nanoscale lateral resolution, thus changing the measurement parameter from spatial dimension to frequency domain.
2Measurement precision
If spectral encoding of spatial frequency is applied, then nanoscale sensitivity is achieved, but depth resolved 3D imaging of scattering objects remains problematic
Solution Approach 1:
The patent segments the axial spatial frequency spectrum into multiple frequency bins or bands, analyzing the dominant frequency content in different depth ranges separately. This segmentation allows the system to handle complex scattering objects by processing different depth regions independently, reducing the complexity of depth-resolved 3D imaging while maintaining nanoscale sensitivity.
Solution Approach 2:
The patent introduces spatial frequency spectra as an intermediary representation between the raw axial OCT data and the final 3D image. By transforming axial depth profiles into spatial frequency domains and using dominant frequencies as mediators to determine lateral positions, the system simplifies the complex task of depth-resolved 3D imaging of scattering objects.
3Measurement precision
If phase OCT is used for vibration measurements, then nanoscale sensitivity in weakly scattering media is achieved, but application to highly scattering media like human tissue is excluded
Solution Approach 1:
The patent changes the measurement parameter from phase information (used in phase OCT for weakly scattering media) to axial spatial frequency content. This parameter change makes the technique robust to scattering effects, as spatial frequency analysis of axial reflections remains valid in highly scattering media like human tissue, thereby improving adaptability while maintaining nanoscale sensitivity.
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, termed nano-scale sensitivity OCT (nsOCT), enables the detection of submicron structures and nano-scale alterations within each voxel, offering improved sensitivity for structural changes, as demonstrated by detecting size differences as small as 20 nm and temporal changes less than 30 nm, with potential applications in medical diagnostics and material science.
Implementation Method 1
an interferometer, and a controller adapted to control the emitter and to process received radiation data according to OCT
Implementation Method 2
Light scattering spectroscopy (LSS) was incorporated in OCT for depth resolved nuclear morphology measurements
Data Source
AI summary
An OCT imaging system (100) comprising a radiation emitter (SLD), a radiation receiver CCD), an interferometer (FC, PC, X-Scan, Y-Scan), a controller (COMP) which controls the emitter and processes received radiation data according to OCT to provide an output image. The controller (COMP) forms a spectrum of spatial frequencies along the depth direction. It calculates from the spectrum local spectra of spatial frequencies or periods along the depth direction for individual volume elements along the depth direction. It translates the local spectra of spatial frequencies or periods along the depth direction into the OCT image domain. It maps the local spectra into the volume elements to provide sensitivity on the nano-scale whereas the volume elements are in the micro-scale. The controller calculates information parameters from the translated and mapped local spectra. Thus the system (100) achieves nano-scale sensitivity although the volume elements are at the micro-scale.