Relay Lens Offset for Recessed APC Connector Inspection

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Solution Overview

Problem

Inspecting angled-polished optical-fiber connectors with deeply recessed endfaces is challenging due to the difficulty in aligning the imaging axis of optical-fiber inspection microscopes, leading to obstruction of illumination light and limited numerical aperture and illumination quality.

Innovation Solution

An adapter tip with a relay lens system that offsets the lens axis relative to the optical-fiber endface to deviate light towards the connector axis, allowing it to exit the connector adapter and be captured by the microscope probe, while maintaining parallel alignment with the connector, reducing interference and improving manufacturing ease.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the imaging axis of the inspection microscope is aligned perpendicularly to the inspected endface, then the illumination light is appropriately captured, but the alignment becomes impractical when inspecting deeply recessed APC connector endfaces

Engineering Contradiction:
Improveimaging qualityVSAvoidalignment practicality
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

A relay lens system is introduced as an intermediary optical component between the angled endface and the microscope objective. The relay lens receives illumination light from the objective and redirects it toward the angled endface, enabling proper illumination capture without requiring the microscope axis to be physically aligned perpendicular to the recessed endface. This mediator resolves the contradiction by decoupling the microscope's fixed alignment from the angled inspection surface.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Illumination intensity

If the lens axis of the relay lens is offset relative to the optical-fiber axis to deviate light, then light obstruction by adapter walls is reduced, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvelight capture efficiencyVSAvoidlens alignment tolerance
Core Design Contradiction:
Illumination intensityVSManufacturing precision

Solution Approach 1:

The relay lens is designed with a specific offset parameter relative to the optical-fiber axis, transforming the optical path geometry to match the angled endface configuration. By carefully selecting and implementing this offset parameter during manufacturing, the design converts a potential precision challenge into a defined geometric relationship that can be consistently reproduced. The offset parameter enables light to bypass adapter walls while the precise definition of this parameter allows for controlled manufacturing.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If the microscope probe is tilted relative to the connector adapter to image the recessed endface, then the endface can be imaged, but the probe interferes with neighboring connectors in high-density patch panels

Engineering Contradiction:
Improveendface imaging capabilityVSAvoidinterference with neighboring connectors
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The relay lens system acts as an optical intermediary that enables the microscope probe to remain in a standard, non-tilted position relative to the connector adapter. The relay lens handles the angular redirection of light, allowing the microscope objective to maintain a straight-on approach that does not interfere with adjacent connectors in high-density configurations. This preserves both imaging capability and spatial compatibility.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Productivity

If a relay lens system with offset lens axis is used, then the object beam is not obstructed by adapter walls, but the device complexity increases

Engineering Contradiction:
Improveinspection efficiencyVSAvoidadapter tip structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The relay lens system is nested within the existing adapter tip structure, integrating the additional optical functionality into the conventional connector interface. The relay lens is housed within the adapter tip's mechanical envelope, allowing the enhanced imaging capability to be added without substantially increasing the overall device footprint or structural complexity. This nested integration enables improved productivity while minimizing the impact on device simplicity.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 solution enables effective imaging of angled-polished optical-fiber connectors by reducing light obstruction, improving alignment, and minimizing manufacturing complexity, thus enhancing the quality and efficiency of optical-fiber connector inspections.

Implementation Method 1

The relay lens system or objective lens receives illumination light reflected from the optical-fiber endface during inspection, the lens axis of each relay lens being offset relative to the optical-fiber endface so as to deviate light reflected from the optical-fiber endface

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3096124B1Adapter tip and microscope system for inspection of fiber-optic connector endface
Publication Date: 2018.09.05 EXFO
  • EP3096124B1 patent drawingFigure 1
  • EP3096124B1 patent drawingFigure 2
  • EP3096124B1 patent drawingFigure 3

AI summary

There is provided an adapter tip to be employed with an optical-fiber inspection microscope probe and an optical-fiber inspection microscope system suitable for imaging the optical-fiber endface of an angled-polished optical-fiber connector deeply recessed within a connector adapter. The adapter tip or microscope system comprises a relay lens system having at least a first relay lens which is disposed so as to directly receive light reflected from the optical-fiber endface during inspection, the lens axis of the first relay lens being offset relative to the optical-fiber endface so as to deviate light reflected from the optical-fiber endface towards the optical-fiber axis of the connector.