Wavelength-Swept Optical Tomograph for High-Speed Imaging
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Solution Overview
Problem
Conventional optical tomographs using FD-OCT face challenges in obtaining high-resolution images at high speeds due to limitations in detector arrays and interference data mixing when using multiple light sources with different wavelengths.
Innovation Solution
An optical tomograph design that employs a light source unit emitting multiple light beams with periodically swept wavelengths, each divided into measuring and reference beams, allowing for simultaneous detection of interference signals from each beam without mixing, using separate light dividing and combining means optimized for each wavelength band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a wide band low coherence light beam is used to improve resolution and image quality, then the number of data points increases, but the cost increases and measurement rates deteriorate due to the need for more detector array elements
Solution Approach 1:
The patent divides the wide wavelength band into multiple separate wavelength bands, with each band detected by a dedicated detector element. This segmentation allows the system to achieve high resolution equivalent to having many detector elements while using only a few elements, thereby maintaining high measurement rates without cost increase or productivity deterioration.
Solution Approach 2:
The patent transitions from detecting all wavelengths simultaneously in the spatial domain (requiring many detector elements) to detecting wavelengths sequentially in the temporal domain using a wavelength-swept light source. This dimensional change from spatial to temporal multiplexing allows high resolution with minimal detector elements, improving measurement rates.
2Measurement precision
If multiple light sources with different wavelengths are used to improve resolution, then the wavelength band increases, but interference data mixing occurs making detection difficult
Solution Approach 1:
The patent performs preliminary wavelength selection by dividing the broad spectrum light into multiple wavelength bands before interference measurement using optical filters or prisms. This preliminary spectral separation prevents interference data mixing by ensuring that each detector element receives interference signals from a specific wavelength band only, making detection straightforward.
Solution Approach 2:
The patent introduces wavelength-selective optical elements (filters or prisms) as intermediaries between the light sources and detectors. These intermediaries separate the spectral components and direct each wavelength band to the appropriate detector element, preventing data mixing and simplifying detection.
3Measurement precision
If the number of detector array elements is increased to increase data points, then resolution improves, but cost increases and productivity decreases
Solution Approach 1:
The patent segments the spectral detection task across multiple detector elements, with each element responsible for a specific wavelength band. This segmentation allows the system to achieve high spectral resolution equivalent to having many elements detect all wavelengths simultaneously, while using only a few elements, thereby reducing device complexity and cost.
Solution Approach 2:
The patent changes the detection parameter from spatial position (detector element position) to wavelength (temporal parameter). By using a wavelength-swept light source, the system maps spectral information to temporal sequences, allowing high resolution with minimal detector elements and reducing device 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 design enables high-resolution tomographic images to be obtained at high speeds with improved measurement rates and simplified apparatus structure, reducing costs and increasing detection accuracy.
Implementation Method 1
Reflected light beams of each wavelength are caused to interfere with reference light beams of each wavelength
Implementation Method 2
an SS-OCT optical tomographs utilizes a light source that periodically sweeps the frequency of a laser beam
Implementation Method 3
a circuit that converts photoelectric current from a detector to digital values
Data Source
AI summary
An optical tomograph is equipped with: a light source unit for emitting a plurality of light beams, the wavelengths of which are swept within different predetermined wavelength bands respectively with the same period; light divider which divides each light beam into a measuring light beam and a reference light beam; light beam combiner which combines reflected light beams, which are the measuring light beams reflected by a measurement target when the measuring light beams are irradiated thereon, with a reference light. An interference light detector detects an interference light beam, which is formed by the reflected light beam and the reference light combined by the light beam combiner, for each of the light beams as an interference signal. A tomographic image processor generates a tomographic image of the measurement target employing the plurality of interference signals detected by the interference light detector.