Broadband Discrete Spectrum Light Source for OCT Depth Resolution
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Solution Overview
Problem
Current Optical Coherence Tomography (OCT) systems, particularly Spectral Domain (SD)-OCT, face limitations in image sensitivity and speed due to low power density from broadband light sources like Super Luminescent Diodes (SLDs), requiring longer integration times and resulting in uncomfortable imaging times for patients.
Innovation Solution
A broadband discrete spectrum light source is configured with a gain medium in a feedback cavity, featuring reflectors with raised-edge reflectivity profiles and post-detection signal processing to enhance bandwidth, output power, and sensitivity, allowing for faster and more sensitive imaging without reaching lasing thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If broadband light sources like Super Luminescent Diodes (SLDs) are used in SD-OCT systems, then the system can achieve spectral domain imaging capability, but the power density is low resulting in low image sensitivity
Solution Approach 1:
The patent segments the broadband spectrum into multiple discrete spectral lines using a Fabry-Perot cavity with specific reflectors. This segmentation allows concentration of power into distinct wavelength components while maintaining broadband coverage, resolving the contradiction between low power density and low sensitivity by redistributing power across segmented spectral channels.
Solution Approach 2:
The patent changes the spectral parameters of the light source by using a Fabry-Perot cavity with controlled reflectivity profiles to generate discrete spectral lines from a broadband source. This parameter transformation converts continuous broadband emission into discrete high-power spectral components, simultaneously improving power density and maintaining spectral domain imaging capability.
2Measurement precision
If longer signal integration time is used at the detector array to improve image sensitivity, then sensitivity increases, but imaging speed decreases
Solution Approach 1:
The patent performs preliminary action by pre-shaping the spectral output of the light source to produce discrete high-power lines before detection. This preliminary spectral conditioning ensures that sufficient power is available at the detector array, allowing for shorter integration times while maintaining sensitivity, thus resolving the speed-sensitivity tradeoff.
3Measurement precision
If the bandwidth of the light source is increased to improve depth resolution, then depth resolution improves, but the power density at each spectral component decreases
Solution Approach 1:
The patent applies local quality by creating discrete spectral lines with high power density at specific wavelength positions while maintaining overall broadband coverage. The Fabry-Perot cavity introduces localized high-reflectivity regions at specific wavelengths, concentrating power locally at these spectral positions while preserving global bandwidth for high depth resolution.
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
The solution significantly improves the bandwidth, depth resolution, and imaging speed of SD-OCT systems, enabling higher resolution and faster acquisition of high-quality 3D images while maintaining safety and reducing patient discomfort.
Implementation Method 1
A broadband discrete spectrum light source is configured with a gain medium in a feedback cavity
Implementation Method 2
reflectors with raised-edge reflectivity profiles
Implementation Method 3
gain medium in a feedback cavity
Data Source
AI summary
A new broadband discrete spectrum light source comprising a gain medium placed in a feedback cavity is disclosed. A design for a feedback cavity including reflectors having raised-edge reflectivity is presented. Bandwidth enhancement is achieved by selectively enhancing the intensity of the discrete emission lines near the band edges of the gain medium spectrum. The bandwidth of a broadband discrete spectrum light source is further enhanced by digitally applying a spectral correction to each detected signal according to a predetermined correction profile. A combined effect of using a broadband discrete spectrum light source and applying spectral correction to the detected signal in an imaging system such as a Spectral Domain Optical Coherence Tomography (SD-OCT) imaging system, results in a desired spectral profile and a bandwidth necessary to achieve higher depth resolution for obtaining high quality diagnostic images.