Fundus Imaging Motion Correction via Cross-Scan Interferometry
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Solution Overview
Problem
Conventional optical image measuring devices fail to correct image distortion caused by movement of living bodies during light beam scanning, leading to inaccurate images, especially when applied to living subjects like the eyes.
Innovation Solution
An optical image measuring device and program that utilize a scanning mechanism to cross-scans the light beam in both main and sub-scanning directions, generating interference light for image formation and processing, allowing for the correction of displacement in formed tomographic images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light beam scans an object to measure surface and internal morphology, then image formation is achieved, but image distortion occurs when the object moves during scanning
Solution Approach 1:
The patent uses a reference mirror to generate reference light that travels a known path and returns to the detector. By comparing the phase and position of the returned signal light with the reference light, the system detects object movement in real-time and applies corrective transformations to the tomographic images, forming a feedback loop that compensates for motion-induced distortion
Solution Approach 2:
The patent introduces a reference mirror as an intermediary element that creates a stable reference light path. This reference mirror serves as a mediator between the light source and the moving object, providing a baseline for comparison that enables the system to distinguish between intentional scanning movements and unintended object motion
2Measurement precision
If scanning time is extended to improve image quality, then measurement accuracy increases, but object movement during scanning causes distortion
Solution Approach 1:
The patent performs preliminary measurements by capturing tomographic images at multiple incident positions before the object moves significantly. By acquiring data at discrete positions in advance and then using reference light comparison to detect and correct movements that occur during the complete scanning cycle, the system ensures high-quality images without requiring the object to remain perfectly stationary throughout the entire scanning duration
3Device complexity
If a single-direction scanning method is used, then device complexity is reduced, but only 2-dimensional tomographic images can be formed
Solution Approach 1:
The patent extends the scanning capability from one dimension to two dimensions by introducing a second scanning mirror that deflects the light beam in a direction perpendicular to the first mirror's scanning direction. This allows the system to illuminate and capture images at multiple incident positions across a two-dimensional surface, transforming the output from 2-dimensional cross-sectional images to three-dimensional volumetric images of the object's internal structure
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
Enables the formation of highly accurate images even when the object moves during scanning by correcting displacement in both perpendicular and depth directions, improving image quality and accuracy.
Implementation Method 1
generating an interference light by overlaying the signal light that has passed through the object to be measured and the reference light that has passed through the reference object
Data Source
AI summary
An optical image measuring device which can form a highly reliable image even if an object moves during scanning of a signal light is provided. An optical image forming device 1 comprises: an interferometer that splits a low coherence light L0 into a signal light LS and a reference light LR and generates an interference light LC by overlaying the signal light LS reflected by a fundus oculi with the reference light LR reflected by a reference mirror 14; a CCD 34 which receives the interference light LC and outputs a detection signal; Galvanometer mirrors 22 and 23 to scan the signal light LS in a main scanning direction and a sub-scanning direction; and a computer 40 forming tomographic images G1 to Gm along the main scanning direction at different positions of the sub-scanning direction. The Galvanometer mirrors 22 and 23 scan the signal light LS in a given direction crossing the main scanning direction, and the computer 40 forms a tomographic image for correction GR along the given direction to correct displacement of each topographic image Gi based on the tomographic image for correction GR.