Ophthalmic Imaging Optical Fiber Ejection End Diameter
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Solution Overview
Problem
Conventional ophthalmic imaging apparatuses using swept source optical coherence tomography (SS-OCT) face challenges in reducing noise, particularly due to light scattering by optical fibers, which complicates the generation of high-quality tomographic images with low signal processing load and can lead to coherence revival ghosts, affecting image quality and sensitivity.
Innovation Solution
The apparatus employs optical fibers with enlarged ejection end diameters for both measurement and reference light paths, reducing reflection and interference noise by increasing the light guide portion diameter at the ejection ends, thereby minimizing coherence revival ghosts and enhancing image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical fibers with standard ejection end diameters are used in SS-OCT apparatus, then the device structure is simple and easy to manufacture, but noise appears in tomographic images due to light scattering and coherence revival ghosts
Solution Approach 1:
The optical fiber is designed with non-uniform structure where the ejection end portion has a different diameter than the main body. Specifically, the ejection end diameter is enlarged to reduce light scattering and coherence revival ghosts, while the main body maintains its original structure for easy connection and manufacturing. This local modification approach improves image quality without significantly increasing overall device complexity.
2Reliability
If signal processing is performed to remove noise components from tomographic images, then image quality can be improved, but the signal processing load increases
Solution Approach 1:
The patent applies preliminary action by modifying the optical fiber ejection end structure before light enters the system. The enlarged ejection end diameter pre-reduces light scattering and coherence revival effects at the source, so that less signal processing is needed later to remove noise. This prevents noise generation rather than just removing it afterward, reducing the processing load.
3Object-affected harmful factors
If the ejection end diameter of optical fibers is enlarged, then reflection and interference noise are reduced, but the optical fiber structure becomes more complex
Solution Approach 1:
The optical fiber structure is modified locally only at the ejection end portion where the diameter is enlarged, while the main body remains unchanged. This localized modification targets the specific location where light scattering and interference occur, reducing harmful effects without requiring complex changes throughout the entire fiber structure.
Solution Approach 2:
The diameter parameter of the optical fiber is changed specifically at the ejection end portion. By adjusting this geometric parameter locally, the patent reduces reflection and interference noise without fundamentally changing the fiber's material composition or overall structure, keeping the modification simple and manufacturable.
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 configuration effectively reduces noise in tomographic images, improving image quality and sensitivity, allowing for higher-speed imaging and broader imaging ranges without the need for extensive signal processing to eliminate coherence revival ghosts.
Implementation Method 1
a first optical fiber disposed in an optical path of the reference light and including a light guide portion for guiding the reference light, and a second optical fiber disposed in an optical path of the measurement light and including a light guide portion for guiding the measurement light
Implementation Method 2
measurement light reflected from a measurement object and reference light reflected from a reference mirror interfere with each other, and time dependency or wavenumber dependency of intensity of the interference light is analyzed to obtain a tomographic image
Data Source
AI summary
An ophthalmic imaging apparatus that captures a tomographic image of an subject's eye based on light obtained by combining a return light with a reference light, the return light being from the subject's eye when irradiated with a measurement light, the reference light corresponding to the measurement light includes a first optical fiber disposed in an optical path of the reference light and including a light guide portion for guiding the reference light, and a second optical fiber disposed in an optical path of the measurement light and including a light guide portion for guiding the measurement light, wherein a diameter of each of the light guide portions of ejection ends of the first optical fiber and the second optical fiber is larger than a diameter of a light guide portion in a position different from a position of each of the ejection ends.