Spectrally Dispersed Illumination OCT for Deep Tissue Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current point-scanning OCT systems in ophthalmology illuminate the eye with less than 10% of the maximum total power due to power limitations, and parallel OCT techniques face image degradation from multiple scattered light, especially when imaging highly scattering samples like the retinal pigment epithelium, leading to challenges in achieving comprehensive sampling and deep tissue imaging.
Innovation Solution
The implementation of spectrally dispersed illumination OCT, where broadband light is distributed as a spectrum onto the sample, allowing each location to be illuminated with a partial bandwidth, and by moving the spectrum, the complete spectral interference information is obtained, enabling full axial resolution and minimizing multiple scattering effects while maintaining confocality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If point-scanning OCT systems are used to illuminate the eye, then the system can maintain confocality and reject out-of-focus light, but the illumination power is limited to less than 10% of the maximum total power
Solution Approach 1:
The broadband light spectrum is segmented into multiple wavelength components that are spatially dispersed across different locations on the sample. Each location receives a partial spectral bandwidth, and by scanning the spectrum across multiple locations, the system achieves both high illumination power and rejection of multiple scattered light through confocal detection.
Solution Approach 2:
The patent introduces spectral dispersion as an additional dimension, spreading the illumination spectrum spatially across multiple locations on the sample. This allows the system to illuminate multiple points simultaneously with different spectral components while maintaining confocality, thereby increasing total illumination power without sacrificing the ability to reject multiple scattered light.
2Illumination intensity
If parallel OCT techniques are used to illuminate multiple locations simultaneously, then higher illumination power can be achieved, but image degradation occurs from multiple scattered light
Solution Approach 1:
The broadband spectrum is segmented into multiple wavelength components that are spatially separated. Each spatial location on the sample is illuminated by a specific spectral component, and the confocal detection scheme ensures that only in-focus light from each location is detected, thereby maintaining image quality while enabling parallel illumination of multiple locations.
Solution Approach 2:
Different spectral components are assigned to different spatial locations on the sample, creating local spectral differentiation. This allows each location to be illuminated with optimized spectral content while the confocal detection maintains local focus rejection, thereby preserving image quality across the entire field of view despite parallel illumination.
3Illumination intensity
If the full broadband spectrum is used for illumination, then maximum illumination power is achieved, but the system cannot maintain confocality and reject multiple scattered light
Solution Approach 1:
The full broadband spectrum is segmented into multiple spectral components that are spatially dispersed to different locations. Each location receives a partial spectrum, and the confocal detection scheme operates independently at each location, maintaining the ability to reject multiple scattered light while utilizing the entire broadband spectrum across the field of view.
Solution Approach 2:
The patent adds spectral dispersion as a spatial dimension, mapping different wavelengths to different locations on the sample. This allows the system to use the full broadband spectrum for illumination while maintaining confocality at each spatial location, as the confocal detection rejects out-of-focus light from each location independently.
4Productivity
If spectral domain OCT is used to recover full depth information from a single exposure, then acquisition speed is improved, but the system requires complex spectral dispersion and detection components
Solution Approach 1:
The spectrometer used in spectral domain OCT serves multiple functions: it disperses the broadband spectrum spatially for confocal detection, enables parallel illumination of multiple locations with different spectral components, and recovers full depth information through Fourier transformation of the spectral interferogram. This multi-functionality achieves high acquisition speed while managing system complexity through a unified optical architecture.
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 allows for higher illumination power within safe limits, achieving high-speed OCT data with full axial resolution and reduced image degradation from multiple scattering, enabling deeper tissue imaging without sacrificing sensitivity.
Implementation Method 1
broadband light is distributed as a spectrum onto the sample
Implementation Method 2
the interfering light is spectrally dispersed by a grating onto a detector array
Implementation Method 3
a Fourier transform is used to recover the depth information
Data Source
AI summary
Systems and methods are presented for acquisition and processing of spectrally dispersed illumination optical coherence tomographic data. Light from a source is distributed spectrally on the sample, and each acquisition simultaneously provides partial spectral interference information from multiple locations in the sample. Thus for a given spatial point, a single observation will be of a partial spectrum A-scan. When multiple partial spectrum A-scan observations are made at the same point by shifting the spectrum of light on to the tissue, the point can be observed by the entire broadband spectrum of the light source, thereby making it possible to create a full axial resolution A-scan.