Swept-Source OCT Spectral Bandwidth Control
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Solution Overview
Problem
Current optical coherence tomography (OCT) systems, particularly swept-source OCT, face limitations in varying measurement depth and axial resolution due to fixed opto-mechanical constraints, making it difficult to image different regions of an object with varying resolutions and depths simultaneously.
Innovation Solution
An apparatus and method for swept-source OCT that employs a spectrally tunable light source and a control device to alter the spectral measurement bandwidth and number of sampling points, allowing for adjustable measurement depth and axial resolution by controlling the light source and detector during the spectral sweep, enabling switching between predefined operating modes with different resolution settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the spectral bandwidth is increased to improve measurement depth, then the axial resolution deteriorates
Solution Approach 1:
The patent implements dynamic adjustment of the spectral measurement bandwidth by controlling the light source to sweep across different spectral ranges. The system can vary the bandwidth Δλ_M dynamically based on the desired measurement depth, allowing adaptive optimization between measurement depth and axial resolution without fixed mechanical constraints
Solution Approach 2:
The system changes the spectral bandwidth parameter Δλ_M as a control variable to adjust the measurement depth z_max. By modifying this parameter along with the number of sampling points N, the system achieves variable measurement depths while maintaining appropriate axial resolution through coordinated parameter adjustment
2Measurement precision
If the spectral bandwidth is decreased to improve axial resolution, then the measurement depth deteriorates
Solution Approach 1:
The system dynamically adjusts the spectral measurement bandwidth downward when high axial resolution is required for detailed imaging of specific structures. This dynamic control allows the system to optimize for fine detail visualization while compensating for reduced measurement depth through selective imaging of relevant regions
Solution Approach 2:
The patent applies local quality by using high-resolution imaging (narrower bandwidth) only for specific regions of interest within the object, rather than uniformly across the entire measurement depth. This allows detailed examination of critical areas while maintaining overall system flexibility
3Length of stationary object
If the number of sampling points is increased to improve measurement depth, then the acquisition time increases
Solution Approach 1:
The system applies partial action by acquiring intensity measurements over only a portion of the total spectral sweep bandwidth (Δλ_M ≤ Δλ). This selective sampling approach obtains sufficient data for the required measurement depth without performing excessive measurements across the entire available spectrum, thereby reducing acquisition time
Solution Approach 2:
The system dynamically adjusts the number of sampling points N and spectral bandwidth Δλ_M based on real-time imaging requirements. When deep imaging is needed, the system increases N and Δλ_M; when shallower imaging suffices, it reduces these parameters, creating an adaptive balance between measurement depth and acquisition time
4Adaptability or versatility
If the system is designed to accommodate variable measurement depths, then the device complexity increases
Solution Approach 1:
The patent achieves variable measurement depth capability using a universal swept-source light source and detector system that can operate across multiple spectral bandwidths. Rather than requiring separate fixed-depth imaging systems, this multi-functional approach uses software control to adapt the same hardware for different measurement depths, reducing overall system complexity
Solution Approach 2:
The system replaces complex mechanical adjustment mechanisms with electronic/software control of the light source sweeping parameters. The control device programmatically adjusts the spectral bandwidth and sampling points without requiring physical reconfiguration, thereby reducing mechanical complexity while maintaining adaptability
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
Enables flexible imaging of varying object regions with differing longitudinal resolutions and measurement depths, enhancing the capability to display detailed sections of the eye or other objects with specific resolution requirements, such as during eye surgery, by varying the spectral bandwidth and number of measurements.
Implementation Method 1
OCT is an imaging method based on the superposition of reference radiation and backscattered (remitted) radiation. It acquires the intensity of the interference signal, i.e. the superposed radiation fields of the reference radiation and of the remitted radiation
Implementation Method 2
SS-OCT typically uses a light source that is spectrally tuneable... as well as a detector such as a single photodiode or a 'balanced detector' with two photodiodes. The interferogram is acquired chronologically over the wavelength λ or the wave number k of the detected light
Data Source
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AI summary
An apparatus for optical swept-source coherence tomography comprises a spectrally tuneable source for emitting coherent light, and a detector for acquiring the intensity of remitted light backscattered from an object irradiated with the coherent light of the source. Further, the apparatus comprises a control device, which is set up to control the light source and the detector in such a way that the detector performs intensity acquisitions in accordance with a defined number of measurements, while the light source is tuned, the control device further being set up, for the purpose of altering the measurement depth or/and the axial resolution of the tomography, to alter the defined number of measurements or/and a spectral measurement bandwidth, within which the detector performs the intensity acquisitions.