Fundus Imaging Parallel Focus and Optical Path Adjustment

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Solution Overview

Problem

Current fundus photographing apparatuses require a lengthy standby period for focus adjustment before performing optical path length adjustment, causing stress for examiners and burdening examinees.

Innovation Solution

A fundus photographing apparatus that includes an interference optical system, a focus detection unit, a focus adjustment unit, and an optical path length adjustment unit, where the optical path length adjustment is performed in parallel with focus detection, allowing for simultaneous adjustment and acquisition of tomographic images without the need for completing focus adjustment first.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If focus adjustment is performed before optical path length adjustment, then measurement precision is improved, but loss of time increases

Engineering Contradiction:
Improvefocus adjustment precisionVSAvoidstandby time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary focus detection and optical path length detection simultaneously before actual photographing, so that when photographing begins, both focus and optical path length are already optimized, eliminating the need for sequential adjustment and standby time

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements continuous detection of focus state and optical path length state during the adjustment process, allowing the system to maintain optimal conditions throughout the photographing sequence rather than requiring discrete adjustment steps with standby periods between them

Inventive Principle:
Principle #20Continuity of useful 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

Enables the acquisition of fundus tomographic images while adjusting photographing conditions efficiently, reducing the standby time and stress for both examiners and examinees.

Implementation Method 1

an interference optical system configured to split a light flux output from a light source into measurement light and reference light, and configured to detect an interference state of the measurement light reflected by the fundus of the examinee's eye and the reference light

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP2638849B1Fundus photographing apparatus
Publication Date: 2018.11.21 NIDEK CO LTD
  • EP2638849B1 patent drawingFigure 1
  • EP2638849B1 patent drawingFigure 2~3
  • EP2638849B1 patent drawingFigure 4~5

AI summary

A fundus photographing apparatus (I) is provided with: a detector (83) that detects an interference state between light reflected from the fundus and reference light; an optical scanner (23) that scans the fundus of an examinee's eye (E) with the measurement light; a focus detection means (300) that detects a focus position with respect to the fundus of the examinee's eye based on an output signal from a light receiving element (68) that receives the light reflected from the fundus; a focus adjustment means (24a) that corrects the diopter scale with respect to the examinee fundus by moving a first optical member (24) to the focus position; a second optical member (31) disposed in the optical path of the measurement light or the reference light; and an optical path length adjustment means (50) that adjusts an optical path length difference between the measurement light and the reference light.