Optical Image Measuring Device for Corneo-Retinal Distance

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Solution Overview

Problem

Conventional optical image measuring devices face challenges in accurately measuring physical quantities across multiple OCT images, particularly in dynamic subjects like the living eye, due to difficulties in synchronizing image acquisition and maintaining high precision over broader measurement ranges.

Innovation Solution

The optical image measuring device employs a configuration with a beam splitter and multiple reference lights with distinct optical paths to generate interference light, allowing for the analysis of multiple tomographic images and calculation of physical quantities such as corneo-retinal distance and magnification, using ocular optical information and alignment processes to ensure accurate measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single reference light path is used in conventional OCT devices, then the device complexity is low, but the measurement precision across multiple sites and broader ranges deteriorates

Engineering Contradiction:
Improvemeasurement precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The reference light is divided into multiple reference lights (first reference light and second reference light) that propagate through different optical paths with different optical path lengths. This segmentation allows simultaneous measurement of multiple sites (e.g., cornea and retina) with different depths, thereby improving measurement precision across broader ranges without requiring sequential scanning

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention extends the measurement capability from a single depth plane to multiple depth planes by introducing multiple reference lights with different optical path lengths. This adds a dimensional aspect to the measurement, enabling simultaneous acquisition of tomographic images at different depths (corneal site and retinal site) in one measurement process

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If multiple tomographic images are acquired sequentially for broader measurement ranges, then the measurement range increases, but the loss of time increases due to sequential acquisition

Engineering Contradiction:
Improvemeasurement rangeVSAvoidtime loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of time

Solution Approach 1:

The invention enables continuous simultaneous measurement of multiple sites by using multiple reference lights that interfere with the signal light at different optical path lengths. This allows the acquisition of multiple tomographic images (corneal image and retinal image) in one continuous measurement process rather than sequentially, thereby reducing time loss while maintaining versatility

Inventive Principle:
Principle #20Continuity of useful action

3Reliability

If conventional single-reference-light OCT is used on dynamic subjects like living eyes, then the device simplicity is maintained, but the reliability of measurements deteriorates due to difficulty in synchronizing image acquisition

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

By segmenting the reference light into multiple reference lights with different optical path lengths, the system can simultaneously capture images of multiple sites (anterior segment and posterior segment) in one measurement instance. This eliminates timing synchronization issues between sequential measurements on dynamic subjects like living eyes, thereby improving reliability

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The optical paths of the multiple reference lights are predetermined and configured with specific optical path length differences before measurement. This preliminary configuration ensures that when the signal light is radiated, the reflected lights from different sites will interfere with the appropriate reference lights simultaneously, ensuring reliable measurements without real-time synchronization adjustments

Inventive Principle:
Principle #10Preliminary action

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 enables high-accuracy measurement of physical quantities across multiple sites of a measured object, improving precision and reliability, especially in dynamic subjects like the living eye, by forming multiple tomographic images and analyzing them to derive accurate corneo-retinal distances and ocular magnifications.

Implementation Method 1

makes the reference light and the signal light interfere with each other to generate an interference light

Methodology Applied
Scientific EffectInterference: Interference

Implementation Method 2

splits the reference light into a plurality of reference lights propagating through a plurality of optical paths

Methodology Applied
Scientific EffectOptical splitting:

Implementation Method 3

acquires the spectral intensity distribution of the interference light to execute Fourier transform

Methodology Applied
Scientific EffectFourier transform:

Data Source

PatentEP2301423B1Optical image measuring device
Publication Date: 2017.05.31 TOPCON CORPORATION
  • EP2301423B1 patent drawingFigure 1
  • EP2301423B1 patent drawingFigure 2A~2B
  • EP2301423B1 patent drawingFigure 3A~3B

AI summary

An optical image measuring device 1 splits low-coherence light L0 into signal light LS and reference light LR, and splits an optical path of the reference light LR into two optical paths having different optical path lengths to split the reference light LR into two reference lights LRa, LRb. Furthermore, the optical image measuring device 1 makes the reference lights LRa, LRb interfere with the signal light LS propagated through an eye E, generates an interference light LC reflecting a morphology in each of two depth positions (fundus oculi Ef and cornea Ec) of an eye E, and detects the interference light LC to generate a detection signal. Then, the optical image measuring device 1 forms a fundus oculi tomographic image and a cornea tomographic image based on the detection signals, and analyzes the tomographic images to obtain a distance between the cornea and retina of the eye E.