Multiple Reference Arm SD-OCT for Depth Sensitivity Decay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional spectral domain optical coherence tomography (SD-OCT) systems suffer from depth-dependent sensitivity decay, particularly when imaging tissues with irregular surface topologies or large luminal organs, due to limited spectral resolution and the ambiguity between negative and positive image depths, which reduces the effective imaging depth range and sensitivity.
Innovation Solution
The implementation of multiple reference arm SD-OCT systems, where the optical delay between reference arms is adjusted to set the most sensitive region near the sample surface, and the use of a fiber delay line to temporally delay interferograms, allowing for the combination of images from multiple reference arm delays to reduce sensitivity roll-off and extend the imaging depth range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the zero delay is set at or outside the tissue surface to avoid mirror image ambiguity, then it is easier to generate images of the tissue, but the depth sensitivity is reduced as the empty space is sampled at high resolution while tissue further from the surface is sampled at lower resolution
Solution Approach 1:
The imaging depth range is divided into multiple segments, with each reference arm optimized for a specific depth range. The first reference arm images the surface region, while the second reference arm images the deeper tissue region, allowing each segment to be optimized for its specific depth range without compromise
Solution Approach 2:
Different reference arms are configured with different optical path lengths to provide locally optimized sensitivity for different depth regions. The first reference arm provides high sensitivity for surface imaging, while the second reference arm provides high sensitivity for deep tissue imaging, allowing each region to have the quality appropriate for its specific imaging needs
2Length of stationary object
If the spectral resolution is increased to extend imaging depth range, then the effective imaging depth range can be increased, but the device complexity increases due to the finite size and number of pixels in the linear detection array
Solution Approach 1:
The spectral detection task is segmented across multiple reference arms, each capturing spectral information optimized for a specific depth range. This allows the system to achieve extended imaging depth range without requiring a single high-resolution spectrometer, thereby reducing device complexity
Solution Approach 2:
The system transitions from a single-dimension spectral resolution approach to a multi-dimensional approach by using multiple reference arms with different optical path lengths. This allows depth range extension through temporal/multipath dimension rather than solely through spectral resolution, reducing the burden on spectrometer complexity
3Measurement precision
If multiple reference arm delays are used to reduce sensitivity roll-off, then the sensitivity and depth penetration are improved, but the device complexity increases due to the need to combine images from multiple reference arm delays
Solution Approach 1:
Images from multiple reference arms with different optical path lengths are merged to produce a composite image with reduced sensitivity roll-off. The processing system combines the spectral data from both reference arms, allowing the benefits of multiple delays to be realized while managing system complexity through integrated processing
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 results in a maximum sensitivity of >105 dB and a minimum sensitivity of 95 dB over a 6-mm ranging depth, enabling clearer visualization of tissue at the edges of the imaging range, with improved sensitivity and depth penetration compared to conventional SD-OCT systems.
Implementation Method 1
combining images obtained from multiple reference arm delays
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
In some embodiments, systems, methods, and media for multiple reference arm spectral domain optical coherence tomography are provided which, in some embodiments, includes: a sample arm coupled to a light source; a first reference arm having a first path length; a second reference arm having a longer second path length; a first optical coupler that combines light from the sample arm and the first reference arm; a second coupler that combines light from the sample arm and the second reference arm; and an optical switch comprising: a first input port coupled to the first optical coupler; a second input coupled to the second coupler via an optical waveguide that induces a delay at least equal to an acquisition time of an image sensor; and an output coupled to the image sensor.