Oscillating Light Pulse Distance Measurement for Ocular Tissue

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Solution Overview

Problem

Current methods for measuring distances within the eye are complex, imprecise, and risk injury, making it difficult to obtain accurate axial length measurements between the cornea and retina.

Innovation Solution

A method using light pulses reflected on the eye's tissue surfaces to measure distance by oscillating a circuit, where the frequency of subsequent light pulses is measured to calculate the distance, with adjustments for component delays and varying light intensities to differentiate reflections from different tissue surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct transit time measurement of light pulses is used, then distance measurement is achieved, but measurement errors are high and results are not usable

Engineering Contradiction:
Improvedistance measurement precisionVSAvoidmeasurement result usability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent employs periodic light pulse emission where each pulse is triggered by the detection of the previous pulse's reflection. This creates a self-sustaining oscillating circuit that generates regularly spaced light pulses, allowing frequency measurement instead of direct transit time measurement. The periodic nature enables stable, repeatable measurements that can be processed to achieve high precision and reliability.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent replaces direct mechanical/time-based measurement with frequency-based measurement. Instead of measuring the transit time of individual light pulses directly, the system measures the frequency of the oscillating circuit formed by periodic pulse emission and detection. This substitution transforms an imprecise direct measurement into a precise frequency measurement that can be easily processed.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Object-affected harmful factors

If complex measuring methods are used to avoid eye injury, then safety is improved, but measurement precision deteriorates

Engineering Contradiction:
Improveeye injury riskVSAvoiddistance measurement precision
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent uses optical measurement with light pulses instead of physical contact methods, eliminating the risk of mechanical injury to the eye. The frequency-based measurement approach provides high precision without requiring complex mechanical or contact-based systems that could potentially harm the eye.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If simple means are used for measurement, then device complexity is reduced, but measurement precision deteriorates

Engineering Contradiction:
Improvemeasurement device complexityVSAvoiddistance measurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces complex direct transit time measurement systems with a simple frequency measurement approach. The oscillating circuit formed by the light source, detector, and trigger mechanism generates pulses whose frequency can be measured with simple equipment. This substitution dramatically reduces device complexity while maintaining or improving measurement precision.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If frequency measurement is used instead of direct transit time measurement, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvedistance measurement precisionVSAvoidoscillating circuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the light source, detector, and trigger mechanism into a single integrated oscillating circuit system. The detector's output directly triggers the light source, which in turn generates the signal detected by the detector, creating a self-sustaining loop. This merging eliminates the need for separate complex timing and control systems, reducing overall device complexity while enabling precise frequency measurement.

Inventive Principle:
Principle #5Merging (Combining)

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 quick, precise distance measurements between tissue surfaces within the eye, reducing measurement errors and allowing for the determination of axial length and height profiles without causing harm.

Implementation Method 1

Since the light pulse and the light pulse reflected on the tissue surface (reflector light pulse) propagate at the speed of light, i.e. very quickly

Methodology Applied
Scientific EffectSpeed of light: Light

Implementation Method 2

light pulses, which are reflected on the corresponding tissue surface

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP1797814B1Method and device for determining the distance to a measuring point on a tissue surface of the eye
Publication Date: 2013.03.13 OCULUS OPTIKGERAETE GMBH
  • EP1797814B1 patent drawingFigure 1
  • EP1797814B1 patent drawingFigure 2
  • EP1797814B1 patent drawingFigure 3

AI summary

The method involves producing a series of light impulse by an impulse light source (3) in dependence of a detection of a reflector light impulse (11). The impulse light source is oscillated with a frequency, where the frequency is measured directly or indirectly. The length (X) of an optical path through a measuring point to a light sensor (4) is derived from the measured value of the frequency and the specific light speed on the basis of the impulse light source. An independent claim is also included for a device for determining a distance of a measuring point from a tissue surface of an eye.