Swept-Wavelength Interferometry Dual-Laser Segmentation
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Solution Overview
Problem
Current OCT and OFDR systems are limited by the slow scan rate of tunable lasers, which restricts spatial resolution and measurement time due to the narrow wavelength range they can scan.
Innovation Solution
Implementing a swept electromagnetic radiation system that uses two spectrally separated wavelength ranges, allowing for faster scan rates and increased spatial resolution by discretely switching between these ranges with minimal transition time, using electronically tunable lasers or multiple sources to generate electromagnetic radiation over wider effective scan ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single tunable laser scans a wide wavelength range to improve spatial resolution, then measurement time increases and scan speed decreases
Solution Approach 1:
The patent divides the wavelength scanning task into multiple segments by using multiple tunable lasers, each responsible for a specific wavelength range. For example, one laser scans 1520-1620 nm while another scans 1280-1380 nm. This segmentation allows parallel acquisition of different wavelength regions, improving spatial resolution through wide effective scan range while reducing total measurement time compared to sequential scanning of a single laser covering the entire range.
Solution Approach 2:
The patent merges the output signals from multiple tunable lasers that scan different wavelength ranges. The controller combines the interferometer signals from each laser to create a composite signal that represents the full wavelength range. This merging approach enables the system to achieve the spatial resolution benefits of wide wavelength scanning while maintaining fast scan rates through parallel operation of multiple lasers.
2Measurement precision
If a single tunable laser scans a wide wavelength range to improve spatial resolution, then scan speed decreases
Solution Approach 1:
The patent segments the total wavelength range into multiple smaller ranges, each handled by a dedicated tunable laser. Each laser only needs to scan its assigned narrow range at high speed, rather than one laser attempting to scan the entire wide range. This segmentation maintains high scan rates for each individual laser while achieving wide effective spectral coverage through combination of multiple lasers.
Solution Approach 2:
The system merges the high-speed scan outputs from multiple lasers operating in parallel. By combining the fast-scanned wavelength regions from multiple sources, the system achieves both high scan rate (inherited from individual laser performance) and wide effective scan range (sum of all laser ranges), thereby improving spatial resolution without sacrificing scan speed.
3Device complexity
If a single tunable laser is used to limit device complexity, then the effective scan range is limited and spatial resolution decreases
Solution Approach 1:
The patent segments the wavelength coverage task across multiple tunable lasers, each handling a portion of the total spectral range. This segmentation increases the effective scan range beyond what a single laser can provide, thereby improving spatial resolution. The added complexity of multiple lasers is offset by the performance gains in resolution and scan speed.
Solution Approach 2:
The patent employs multiple tunable lasers that can be configured to scan different wavelength ranges, making the system universally capable of covering a broad spectral range. Each laser serves multiple functions: it provides high-speed scanning capability, covers a specific wavelength region, and contributes to the overall wide spectral coverage when combined with other lasers, thereby achieving high spatial resolution without excessive complexity.
4Loss of time
If a single tunable laser scans continuously to reduce measurement time, then spatial resolution is limited by the maximum scan range
Solution Approach 1:
The patent merges the scanning capabilities of multiple tunable lasers operating in parallel to achieve both wide effective scan range and fast measurement speed. By combining the outputs of multiple lasers that each scan their assigned wavelength ranges simultaneously, the system achieves wide spectral coverage (improving spatial resolution) while maintaining short measurement times through parallel operation, avoiding the trade-off present in single-laser 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
This approach significantly reduces measurement time and enhances spatial resolution by leveraging the wide wavelength separation between measurement regions, achieving higher resolution than traditional systems while minimizing signal processing burden.
Implementation Method 1
at least one electromagnetic radiation source operable to generate electromagnetic radiation through a first range of wavelengths and a second range of wavelengths, wherein the first range of wavelengths and the second range of wavelengths are spectrally separated
Implementation Method 2
an interferometer coupled to the at least one electromagnetic radiation source, wherein the interferometer includes a reference path and a sample path
Implementation Method 3
a detector for receiving electromagnetic radiation returned from the reference path and the sample path, wherein the detector generates output signals corresponding to the received electromagnetic radiation
Data Source
AI summary
A system and method for measuring an interferometric signal from a swept-wavelength interferometer by scanning a tunable laser source over two wavelength ranges, whose centers are separated substantially more than the length of wavelength ranges. The spatial resolution of the measurement is determined by the inverse of the wavelength separation between a first and second wavelength region, as well as by the wavelength range of the first and second regions. An electronically tunable laser may be utilized to produce two wavelength ranges that are widely separated in wavelength. Such a system and method has wide applications to the fields of optical frequency domain reflectometry (OFDR) and swept-wavelength optical coherence tomography (OCT), for example.