Common-Path Handheld OCT Probe for Noise-Free Imaging
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Solution Overview
Problem
Conventional parallel optical coherence tomography (OCT) apparatuses using optical fibers suffer from noise due to phase differences in light interference when the optical fiber cables are moved or wobbled, limiting their applicability, especially in handheld devices where stability and accuracy of tomographic images are crucial.
Innovation Solution
A common-path optical fiber-based handheld OCT apparatus is designed with flexible optical fiber cables and a probe that includes a broadband light source, spectrometer, optical fiber circulator, collimator, diffraction grating, relay lens, galvanometer scanner, and interferer, allowing for stable light interference and image capture without the need for fixed optical fiber cables, enabling flexible handling and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If optical fiber cables are used to transfer light in parallel OCT apparatus, then the device can be made handheld and flexible, but noise occurs due to phase difference changes when the cables are moved or wobbled
Solution Approach 1:
The patent merges the reference light path and measurement light path into a single common optical path. Both lights travel through the same optical fiber cable, so any movement or wobble affects both paths equally, maintaining their phase relationship and eliminating noise in the tomographic image while preserving handheld flexibility.
Solution Approach 2:
The patent introduces a circulator as an intermediary device that directs light through a common fiber optic path. The circulator ensures that reference light and measurement light share the same transmission medium, acting as a mediator that equalizes the optical paths and prevents phase difference variations caused by cable movement.
2Reliability
If a two-arm type interferometer is used with stationary paths, then stable light interference can be achieved, but the device complexity increases and fixed positioning is required
Solution Approach 1:
The patent combines two separate optical paths (reference arm and measurement arm) into a single common path through the use of a circulator. This merging approach maintains the stability of light interference while significantly simplifying the optical configuration and eliminating the need for complex fixed positioning mechanisms.
Solution Approach 2:
Instead of using the conventional two-arm configuration where reference and measurement lights travel through separate stationary paths, the patent inverts the approach by having both lights travel through a single moving path. This inversion maintains interference stability while reducing mechanical complexity.
3Adaptability or versatility
If optical fiber cables are wobbled during image capture, then handheld operation becomes possible, but noise is generated due to phase difference changes
Solution Approach 1:
The patent merges reference light and measurement light into a common optical path through the circulator. When the optical fiber cable is wobbled during handheld operation, both light paths experience identical phase changes, which cancel out in the interference measurement, thereby maintaining tomographic image accuracy while enabling handheld operation.
Solution Approach 2:
The patent converts the harmful effect of cable wobble into a beneficial common-mode signal. By having both reference and measurement lights travel through the same cable, the wobble-induced phase changes affect both paths equally, allowing the system to reject this disturbance and maintain measurement precision during handheld operation.
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
The solution provides a stable and accurate tomographic image acquisition, even when the optical fiber cables are wobbled, enhancing the usability of the OCT apparatus in handheld forms and allowing for the application of a small-sized probe in endoscopes, with improved image quality and reduced noise compared to traditional two-arm OCT systems.
Implementation Method 1
a first optical fiber cable configured to connect the broadband light source and the optical fiber circulator, and formed of a flexible material, a second optical fiber cable configured to connect the probe and the optical fiber circulator
Implementation Method 2
a diffraction grating configured to diffract the light having passed through the collimator
Implementation Method 3
an objective lens configured to concentrate the reflected light on a focal point
Implementation Method 4
an interferer configured to acquire an interfered light by reflecting at least a portion of the light having passed through the objective lens
Data Source
AI summary
Provided is a common-path optical fiber-based handheld parallel optical coherence tomography (OCT) apparatus, including a probe configured to receive the light from a broadband light source and illuminate a measurement target, wherein the probe may include an inner space through which the light passes, a collimator configured to collimate the light incident to the inner space, a diffraction grating configured to diffract the light having passed through the collimator, a galvanometer scanner configured to reflect the light having passed through the diffraction grating, an objective lens configured to concentrate the reflected light on a focal point, and an interferer configured to acquire an interfered light by reflecting at least a portion of the light having passed through the objective lens.