Multiple Depth OCT System Dispersion Encoding
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Solution Overview
Problem
Current Fourier domain optical coherence tomography (FD-OCT) systems face limitations such as a sample-independent limited depth range due to complex conjugate ambiguity and sensitivity fall-off, which restricts usable imaging depth to less than 2 mm, making it inadequate for imaging the full axial length of the human eye, typically requiring multiple scans for ophthalmic examinations.
Innovation Solution
A multiple depth OCT system is developed that uses a dispersive medium to separate and encode return light from different depth positions within a sample, allowing for the use of matched reference arms to decode dispersion differences, enabling simultaneous imaging at multiple depths by separating components of the spectral interferogram based on their dispersion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional FD-OCT is used, then imaging speed and signal to noise ratio are improved, but usable imaging depth is limited to less than 2mm due to complex conjugate ambiguity and sensitivity fall-off
Solution Approach 1:
The invention divides the single reference arm into multiple reference arms (first reference arm and second reference arm), each configured to match dispersion characteristics of different depth positions in the sample. This segmentation allows simultaneous imaging at multiple depth positions while maintaining the speed advantages of FD-OCT.
Solution Approach 2:
Each reference arm is tailored with specific dispersion characteristics matched to its corresponding depth position in the sample. The first reference arm matches the dispersion of the first depth position, while the second reference arm matches the dispersion of the second depth position, enabling optimized imaging at each depth range.
2Length of stationary object
If full range OCT techniques are used to eliminate complex conjugate artifacts, then measurement range is doubled to about 4mm, but this is still insufficient for imaging the full axial length of the human eye (24mm)
Solution Approach 1:
The invention segments the imaging task into multiple depth ranges by using multiple reference arms, each optimized for a specific depth position. This allows the system to achieve comprehensive coverage of the entire eye (up to 24mm axial length) by combining images from multiple depth positions, rather than attempting to image the entire range with a single reference arm.
Solution Approach 2:
The multiple depth OCT system provides universal imaging capability across the entire axial length of the human eye by integrating multiple reference arms. Each reference arm handles a specific depth range, and together they provide comprehensive imaging coverage for anterior eye structures, retina, and axial length measurement in a single scan.
3Loss of information
If multiple separate OCT measurements are used to image retina, anterior eye, and axial length, then comprehensive ophthalmic data is obtained, but imaging time and procedure complexity increase
Solution Approach 1:
The invention merges multiple imaging functions (anterior eye imaging, retinal imaging, and axial length measurement) into a single OCT scan by combining multiple reference arms. This allows comprehensive ophthalmic data to be obtained in one scan, eliminating the need for multiple separate measurements and reducing imaging time and procedure complexity.
Solution Approach 2:
The multiple depth OCT system achieves multi-functionality by enabling anterior eye imaging, retinal imaging, and axial length measurement simultaneously through a single integrated system with multiple reference arms, providing comprehensive ophthalmic diagnostics in one procedure.
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 effectively doubles the usable imaging depth, allowing for comprehensive imaging of the eye, including both the anterior chamber and retina in a single scan, overcoming the limitations of conventional FD-OCT systems and improving ophthalmic diagnostics.
Implementation Method 1
A multiple depth OCT system in which OCT return light from different depth positions separated by a dispersive medium in a sample have different dispersions
Implementation Method 2
An OCT detector is configured to measure a spectral interferogram based on the combined beams
Data Source
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AI summary
An OCT system for imaging multiple depth positions includes a light source, a sample arm and two or more reference arms. The sample arm propagates light to the object and directs object return light having a first return light beam from a first position and a second return light beam from a second position, the second return light having a dispersion level higher than the first return light beam by a dispersion difference amount. The first and second reference arms produce light beams having substantially the same dispersion as the first and second return light beams, respectively. The optical pathway combines all of the object return light and the reference light beams. An OCT detector measures the resulting interferogram. Imaging information is obtained for both the first position and the second position based on the dispersion difference amount.