SS-OCT Depth Profile Extraction via Compressed Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The axial resolution in Optical Coherence Tomography (OCT) systems is limited by the wavelength range of the light source used, leading to difficulties in distinguishing multiple scattering peaks with similar depths due to strong side-lobes in the depth profiles obtained, especially when using multiple wavelength-tunable light sources.
Innovation Solution
The use of compressed sensing techniques, combined with optimization of wavelength ranges for multiple wavelength-tunable light sources, to extract high axial-resolution depth profiles, reducing side-lobes and enhancing the accuracy of depth profile extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple wavelength-tunable light sources with varying wavelength ranges are used to enhance axial resolution, then the axial resolution is improved, but strong side-lobes appear in the depth profiles making it difficult to distinguish multiple scattering peaks
Solution Approach 1:
The patent divides the wavelength tuning process into multiple discrete sampling points across the wavelength range. Instead of continuous tuning, the spectrum is segmented into N discrete wavelength points that are sequentially sampled, which allows for controlled acquisition of spectral data while managing the side-lobe issue through structured sampling.
Solution Approach 2:
The patent employs periodic modulation of the reference arm optical path length during spectral acquisition. By periodically varying the reference path length in synchronization with the wavelength tuning, the system encodes depth information in a periodic manner that enables separation of overlapping scattering peaks and reduction of side-lobe artifacts through Fourier transformation.
2Device complexity
If a single wavelength-tunable light source is used, then the device complexity is reduced, but the axial resolution is limited by the wavelength range
Solution Approach 1:
The patent uses a dynamically tunable single light source that can sweep through a wide wavelength range. The wavelength-tunable laser is controlled to sequentially emit at different wavelengths across the spectrum, effectively replacing multiple fixed-wavelength sources with one dynamic source that provides the same spectral coverage through time-varying operation.
Solution Approach 2:
The patent transitions from spatial multiplexing of multiple light sources to temporal multiplexing with a single tunable source. By adding the time dimension to the wavelength dimension, the system acquires spectral data sequentially over time rather than simultaneously in space, reducing hardware complexity while maintaining spectral coverage.
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 allows for the acquisition of high axial-resolution tomographic images with reduced side-lobes, improving the detection of multiple peaks and reliability of depth profiles in OCT systems.
Implementation Method 1
The sample optical signal illuminates a sample and the light backscattered from the sample is collected. This backscattered light is subsequently combined with the reference optical signal, which interferes with the collected backscatter light to produce an interference signal.
Implementation Method 2
By sweeping the wavelength of the wavelength-tunable light source, the interference signal is measured over a finite wavelength range. By taking the Fourier Transform of the interference signal, a scattering profile of the sample in the axial direction of the sample light, henceforth referred to as the depth profile of the sample, is able to be extracted.
Data Source
AI summary
A swept-source optical coherence tomography (SS-OCT) apparatus includes a plurality of wavelength-tunable light sources. The SS-OCT apparatus includes a first optical coupler configured to receive an output from each of the plurality of wavelength-tunable light sources. The optical coupler is configured to split the received output from the plurality of wavelength-tunable light sources into a reference optical path and a sample optical path. The sample optical path is configured to illuminate a sample. The SS-OCT apparatus includes a second optical coupler configured to receive return optical signals from the reference optical path and the sample optical path, and to output an optical interference signal. The SS-OCT apparatus includes a detector configured to detect the optical interference signal; and a controller configured to receive an electrical signal based on the detected optical interference signal. The controller is configured to generate a depth profile of the sample using compressed sensing.