Multiplexed MEMS VCL Swept Source for OCT Imaging
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Solution Overview
Problem
Current swept source optical coherence tomography (SS-OCT) systems are limited by mechanical resonance and dynamic properties of single MEMS actuators, restricting imaging rates and wavelength sweep ranges, and lack flexibility in operation.
Innovation Solution
A system comprising multiple MEMS-tunable vertical cavity lasers (VCLs) with different mechanical resonances and wavelength repetition rates, configured to emit multiplexed wavelength-swept radiation, where each VCL is driven over an identical or different wavelength range at varying repetition rates, and selectively turned on/off to achieve bi-directional tuning and extended imaging capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single MEMS-tunable VCL is used as a swept source, then the system achieves single-mode mode-hop-free operation with long coherence lengths, but the imaging rates and wavelength sweep ranges are limited by the mechanical resonance and dynamic properties of the single MEMS actuator
Solution Approach 1:
The patent divides the single laser source into multiple separate VCLs, each operating at different repetition rates. This segmentation allows each laser to operate independently within its optimal performance range while collectively providing extended functionality. The multiple VCLs are combined through optical multiplexing to create a unified swept source system that overcomes the limitations of any single actuator.
Solution Approach 2:
The patent combines multiple VCL outputs into a single multiplexed beam using optical combining techniques. This merging allows the system to integrate the capabilities of multiple lasers with different repetition rates into one unified source, achieving both high-speed imaging capability and extended wavelength sweep range while maintaining the coherence benefits of individual single-mode operations.
2Reliability
If a single MEMS-tunable VCL is used as a swept source, then the system achieves narrow linewidth operation, but the wavelength sweep range is limited by the gain-bandwidth of the single semiconductor gain medium
Solution Approach 1:
The patent segments the wavelength sweep function across multiple VCLs, each tuned to operate within specific wavelength ranges. This allows the system to achieve a cumulative wavelength sweep range that exceeds the gain-bandwidth limitation of any single semiconductor gain medium, while each individual VCL maintains its narrow linewidth characteristics within its operational range.
Solution Approach 2:
The patent creates a multi-functional swept source system where multiple VCLs with different wavelength ranges and repetition rates work together. This universal system can adapt to various imaging requirements by selectively activating appropriate VCLs or combining their outputs, providing both narrow linewidth performance and extended wavelength coverage.
3Use of energy by moving object
If the MEMS-VCSEL is operated at mechanical resonance in a vacuum environment, then low voltage operation is achieved, but the wavelength repetition rate is constrained by the mechanical resonance frequency
Solution Approach 1:
The patent assigns different operational characteristics to different VCLs, with each optimized for specific repetition rates and voltage requirements. This local optimization allows the system to maintain low voltage operation for VCLs operating at mechanical resonance while incorporating other VCLs that operate at higher repetition rates, providing flexibility without sacrificing energy efficiency in critical applications.
Solution Approach 2:
The patent creates a dynamic system where multiple VCLs with different mechanical resonances and repetition rates can be selectively activated. This dynamic configuration allows the system to adapt its repetition rate based on imaging requirements while maintaining the energy-efficient low voltage operation of VCLs operated at their mechanical resonance frequencies.
4Productivity
If multiple VCLs with different repetition rates are used, then imaging speed and wavelength sweep range are enhanced, but the system complexity increases
Solution Approach 1:
The patent combines multiple VCL outputs into a single multiplexed beam using optical combining techniques, which simplifies the overall system architecture despite using multiple lasers. This merging approach allows the system to achieve high imaging speeds and extended wavelength ranges while maintaining a relatively compact and manageable configuration compared to using multiple independent imaging systems.
Solution Approach 2:
The patent creates a universal swept source platform where multiple VCLs with different characteristics can be integrated into a single system. This multi-functional approach allows the system to perform various imaging tasks with different speed and range requirements using a unified configuration, reducing the need for multiple separate systems and simplifying operational complexity.
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 configuration enhances imaging speed, resolution, and flexibility, allowing for superior imaging quality and extended wavelength sweep ranges, enabling more versatile applications such as high-speed and long-range imaging in OCT systems.
Implementation Method 1
an optical detector for detecting an interference signal created by an optical interference between a reflection from the sample and light traversing the reference path
Implementation Method 2
limited by the mechanical resonance and dynamic properties of a single MEMS actuator
Data Source
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AI summary
A system for swept source optical coherence tomography, the system including a light source emitting multiplexed wavelength-swept radiation over a total wavelength range, the light source including N wavelength-swept vertical cavity lasers (VCL) emitting N tunable VCL outputs having N wavelength trajectories, a combiner for combining the N tunable VCL optical outputs into a common optical path to create the multiplexed wavelength-swept radiation, a splitter for splitting the multiplexed wavelength- swept radiation to a sample and a reference path, an optical detector for detecting an interference signal created by an optical interference between a reflection from the sample and light traversing the reference path, and a signal processing system which uses the interference signal to construct an image of the sample, wherein at least one of the N wavelength trajectories differs from another of the N wavelength trajectories with respect to at least one parameter.