Optical Fiber Alignment via Side Image Correlation

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Solution Overview

Problem

Existing alignment apparatuses for optical fibers face challenges in efficiently aligning multi-core fibers, particularly in fields where active alignment is not feasible, and struggle to accurately connect each core due to the complexity of optical systems and unclear influence of hole markers on connection characteristics.

Innovation Solution

An alignment apparatus that includes a control unit, photographing unit, and grippers to rotate and align multi-core optical fibers by calculating correlation coefficients from side images, allowing for precise rotation angle adjustment to maximize light power transfer and minimize connection losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If active alignment is used to align rotation angle, then alignment precision is improved, but device complexity and power requirements increase making it unsuitable for field work

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

Solution Approach 1:

The patent replaces the mechanical/optical active alignment system with a passive image-processing-based alignment system. The photographing unit captures images of the optical fiber side, and the control unit calculates correlation coefficients to determine rotation angle, eliminating the need for complex active alignment mechanisms and power monitoring equipment.

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

Solution Approach 2:

The patent uses optical copying by photographing the side image of the optical fiber containing the hole marker. The control unit processes this copied visual information through correlation coefficient calculation to determine alignment parameters, replacing direct mechanical/optical measurement methods.

Inventive Principle:
Principle #26Copying

2Measurement precision

If alignment is performed by observing end face with complicated optical system, then core positioning precision is improved, but device complexity increases

Engineering Contradiction:
Improvecore positioning precisionVSAvoidoptical system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transitions from observing the end face (one-dimensional cross-section view) to observing the side of the optical fiber (lateral view). This dimensional change allows use of simpler optical systems while maintaining alignment precision through side image correlation analysis.

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

Solution Approach 2:

The patent replaces complex optical measurement systems with an image processing system. By photographing the side image and calculating correlation coefficients, the system achieves core positioning without requiring complicated optical components such as mirrors and specialized end-face observation systems.

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

3Adaptability or versatility

If two types of different hole markers are used for side observation, then alignment capability is improved, but connection characteristics become uncertain and device complexity increases

Engineering Contradiction:
Improvealignment capabilityVSAvoidconnection characteristics
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent uses a single type of hole marker instead of two different types. The uniform hole marker simplifies the alignment system while the control unit compensates for any limitations through correlation coefficient calculation, ensuring both alignment capability and connection reliability.

Inventive Principle:
Principle #33Homogeneity

Solution Approach 2:

The single hole marker serves multiple functions: it provides reference for rotation angle alignment and enables correlation coefficient calculation. The control unit processes the side image containing this universal marker to achieve both rotational and positional alignment without requiring multiple specialized markers.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Productivity

If rotation alignment is applied to multi-core optical fiber, then alignment speed is improved, but core identification precision deteriorates

Engineering Contradiction:
Improvealignment speedVSAvoidcore identification precision
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent segments the alignment process into two independent stages: first determining rotation angle through side image correlation, then determining core position through end face image analysis. This segmentation allows rotation alignment to proceed quickly while maintaining precise core identification in the subsequent stage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary rotation angle alignment using side image correlation before proceeding to core identification. This preliminary action positions the optical fibers at the correct rotation angle, making subsequent core identification easier and more accurate while maintaining overall alignment speed.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3379307B9Alignment device and alignment method
Publication Date: 2021.10.27 NIPPON TELEGRAPH & TELEPHONE CORP
  • EP3379307B9 patent drawingFigure 1~2
  • EP3379307B9 patent drawingFigure 3
  • EP3379307B9 patent drawingFigure 4

AI summary

An alignment apparatus that can efficiently align an optical fiber, and an alignment method will be provided. According to the embodiments, the alignment apparatus that aligns an optical fiber comprises an acquisition unit, a calculation unit, and a rotation processing unit. The acquisition unit acquires one or more side images of the optical fiber. The calculation unit calculates correlation coefficients between the luminances of the one or more side images and those of one or more reference side images. The rotation processing unit rotates the optical fiber in the axis direction of the optical fiber so that the correlation coefficients peak.