1-Micron Microcomb OCT Axial Resolution via Silicon Nitride Resonators
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Solution Overview
Problem
Current optical coherence tomography (OCT) systems using laser frequency microcombs are limited in axial resolution, which is insufficient for imaging intricate body tissues, as they typically operate with light sources generating images with axial resolutions of around 20 μm, whereas more detailed resolutions are required for complex tissue imaging.
Innovation Solution
The use of 1-μm laser frequency microcombs generated by silicon nitride microresonators, optimized for spectral domain OCT, which includes a microresonator structure capable of producing microcombs with specific free spectral ranges and bandwidths, coupled with advanced processing techniques like noise reduction and phase correction, to achieve improved axial resolution and imaging depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional laser sources are used in OCT systems, then the system is simpler and easier to manufacture, but the axial resolution is limited to around 20 μm which is insufficient for imaging intricate body tissues
Solution Approach 1:
The patent changes the fundamental parameter of the light source from conventional lasers to frequency-comb lasers with specific spectral characteristics. This parameter change enables axial resolution of 5.6±1.7 μm, dramatically improving measurement precision while the system architecture remains based on standard OCT components
Solution Approach 2:
The frequency-comb laser source segments the spectrum into discrete frequency lines, allowing precise control over the spectral content. This segmentation enables improved axial resolution by providing well-defined frequency components that enhance the coherence properties needed for high-resolution imaging
2Measurement precision
If higher axial resolution is achieved through improved light sources, then imaging detail is enhanced, but power exposure to the sample increases
Solution Approach 1:
The frequency-comb laser provides periodic spectral lines that can be synchronized with the OCT measurement process. This periodic structure allows for reduced peak power exposure while maintaining sufficient coherence for high-resolution imaging, as the energy is distributed across multiple discrete frequency components rather than a continuous spectrum
3Measurement precision
If conventional OCT systems are used, then the acquisition speed is moderate, but the imaging depth is limited and resolution is insufficient for complex tissues
Solution Approach 1:
The frequency-comb laser source provides multiple functional benefits simultaneously: high axial resolution, extended imaging depth, and maintained acquisition speed. The discrete frequency lines enable precise spectral analysis for deep tissue imaging while preserving the speed advantages of conventional OCT systems
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 system achieves axial resolutions of 5.6±1.7 μm, significantly exceeding commercial OCT systems, providing detailed cross-sectional images of biological tissues with enhanced imaging depth and reduced power exposure, while maintaining improved sensitivity and acquisition speed.
Implementation Method 1
a microresonator configured to receive the amplified laser beam and couple the received laser beam into the microresonator to generate a microcomb laser
Implementation Method 2
generate a microcomb laser with a desired free spectral range and bandwidth
Implementation Method 3
a grating configured to filter the generated microcomb laser
Implementation Method 4
an interferometer configured to split the generated microcomb laser into a sample arm and a reference arm
Implementation Method 5
a collimator configured to collect and transmit an interferogram of the sample arm laser reflected off the target interfering with the reference arm
Implementation Method 6
a transmission grating configured to diffract the interferogram onto a set of one or more imaging lens
Implementation Method 7
a set of one or more imaging lens configured to project the pattern of the interferogram onto a line scan camera
Data Source
AI summary
Systems and methods for performing optical coherence tomography (OCT) on a target using microcomb lasers in accordance with embodiments of the invention are illustrated. One embodiment includes an OCT system that includes a laser generator configured to generate a laser beam, and an optical amplifier configured to amplify the laser beam, a microresonator configured to receive the amplified laser beam and couple the received laser beam into the microresonator to generate a microcomb laser, a grating configured to filter the generated microcomb laser, an interferometer configured to split the generated microcomb laser into a sample arm and a reference arm, an OCT probe configured to generate tomograms of a target using the sample arm, and a spectrometer configured to obtain depth information from the interferogram and generate cross-sectional images of the target based on the obtained depth information.