Variable-Cross-Section Glass Waveguide for Compact Light Delivery

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Solution Overview

Problem

Existing dental light-curing devices using fiber optics require large light guides to deliver sufficient light intensity, which are inconvenient for patients and difficult to maneuver, and existing methods for producing tapered optical fibers are inefficient in maintaining light concentration and ease of handling.

Innovation Solution

The production of tapered optical fibers with a dumbbell-shaped cross-section, featuring two end sections with a larger cross-sectional area and a central section with a smaller area, allowing for continuous cross-sectional change, is achieved through controlled heating and stretching of a glass rod using localized heating and precise velocity profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If large light guides are used to deliver sufficient light intensity, then light delivery capability is improved, but instrument size and maneuverability deteriorate

Engineering Contradiction:
Improvelight delivery capabilityVSAvoidmaneuverability
Core Design Contradiction:
Illumination intensityVSEase of operation

Solution Approach 1:

The optical fiber is segmented into multiple cross-sectional regions along its length, with each section having a different cross-sectional area. The proximal section has a larger cross-section for light coupling, the intermediate section tapers to a smaller cross-section for maneuverability, and the distal section maintains the smaller cross-section for insertion. This segmentation allows the fiber to deliver sufficient light while being easy to maneuver in the oral cavity.

Inventive Principle:
Principle #1Segmentation

2Shape

If tapered optical fibers are produced by conventional heating and stretching, then fiber tapering is achieved, but light concentration and handling ease deteriorate

Engineering Contradiction:
Improvefiber taperingVSAvoidhandling ease
Core Design Contradiction:
ShapeVSEase of operation

Solution Approach 1:

The heating and stretching process is applied locally to specific sections of the glass rod rather than uniformly throughout. The intermediate section is selectively heated and stretched to create the tapered transition, while the proximal and distal sections maintain their original dimensions. This local quality approach creates the desired tapering while preserving handling ease in the uniform sections.

Inventive Principle:
Principle #3Local quality

3Shape

If the glass rod is heated and stretched to form tapered fibers, then fiber shape is improved, but manufacturing precision deteriorates

Engineering Contradiction:
Improvetapered fiber shapeVSAvoidcross-sectional uniformity
Core Design Contradiction:
ShapeVSManufacturing precision

Solution Approach 1:

The glass rod is pre-formed with a specific geometry before the heating and stretching process. The rod includes a proximal section, an intermediate section, and a distal section with predetermined dimensions. This preliminary action ensures that when the intermediate section is heated and stretched, the resulting tapered fiber maintains precise cross-sectional uniformity in the proximal and distal sections while achieving the desired tapering shape.

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 method enhances light concentration and ease of handling, reducing the size and complexity of dental instruments while maintaining effective light delivery, improving maneuverability and hygiene.

Implementation Method 1

a longitudinal section is illuminated by a light source until the glass softens

Methodology Applied
Scientific EffectHeating: Heating

Implementation Method 2

The glass element is produced by drawing. The shape of the glass element is thus achieved by hot forming

Methodology Applied
Scientific EffectInfrared radiation: Infrared Radiation

Implementation Method 3

The glass element has a second, central longitudinal section located between the first longitudinal sections, with a second cross-sectional area that is smaller than the first cross-sectional area

Methodology Applied
Scientific EffectGravity: Gravitation

Data Source

PatentEP3931159B1Glass optical waveguide with variable cross section
Publication Date: 2026.01.14 SCHOTT AG
  • EP3931159B1 patent drawingFigure 1~4
  • EP3931159B1 patent drawingFigure 5
  • EP3931159B1 patent drawingFigure 6

AI summary

The invention relates to a drawn glass element (2) for producing glass optical waveguides (1), comprising - two first length portions (5, 7) which have a first cross-sectional area and which form the two ends of the glass element (2), - a second, central length portion (9) which is situated between the first length portions (5, 7) and which has a second cross-sectional area smaller than the first cross-sectional area of the first length portions (5, 7), and two transition portions (11, 13) in each case between the central length portion (9) and the first length portions (5, 7), wherein the cross-sectional area of the glass element continuously varies, and transitions from the first cross-sectional area into the second cross-sectional area, along the transition portions (11, 13).