Chromatic Confocal Sensor Fiber Interface Aperture

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Solution Overview

Problem

Existing chromatic point sensor (CPS) optical pens for confocal range sensing require recalibration and factory servicing when the optical fiber is replaced, making them inconvenient and expensive to maintain.

Innovation Solution

A fiber optic interface configuration with a fixed aperture element inclined at an angle, allowing standard optical fiber connectors to be used without altering performance, enabling easier interchangeability and control of aperture properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the end of the optical fiber is tapered to provide a smaller detector aperture, then measurement resolution is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvemeasurement resolutionVSAvoidfiber processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention separates the fiber coupling function from the aperture function by introducing a distinct aperture plate component. The optical fiber maintains its standard diameter for easy coupling, while the aperture is defined by a separate plate with a precisely controlled opening, eliminating the need to taper the fiber itself.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

An aperture plate is introduced as an intermediary component between the optical fiber and the measurement system. This plate with a defined aperture opening allows the fiber to maintain its standard diameter while still achieving the desired aperture effect for high-resolution measurements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of repair

If the optical fiber is replaced, then maintenance is enabled, but recalibration and factory servicing are required

Engineering Contradiction:
Improvefiber replaceabilityVSAvoidmeasurement consistency
Core Design Contradiction:
Ease of repairVSReliability

Solution Approach 1:

The aperture plate is designed as a universal component that works with standard diameter optical fibers. This allows different fibers to be interchangeably coupled to the same aperture plate assembly, maintaining measurement consistency without requiring recalibration or specialized servicing.

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

Solution Approach 2:

The invention changes the critical aperture-defining parameter from fiber diameter (which varies with tapering) to aperture plate opening size (which can be precisely controlled and replicated). This parameter change enables consistent performance across multiple fibers while allowing easy fiber replacement.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If a smaller detector aperture is used, then measurement resolution is improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improvemeasurement resolutionVSAvoidaperture fabrication precision
Core Design Contradiction:
Measurement precisionVSManufacturing precision

Solution Approach 1:

The aperture function is extracted from the optical fiber and placed in a separate aperture plate. This allows the aperture to be fabricated with high precision using appropriate techniques for the plate material, while the fiber itself can be handled with standard tolerances, separating the precision requirements from the fiber assembly process.

Inventive Principle:
Principle #2Taking out (Extraction)

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 configuration maintains measurement resolution without tapering the fiber, simplifies assembly, and reduces performance variations between devices, allowing for interchangeable optical fibers without recalibration.

Implementation Method 1

an optical element portion that provides longitudinal chromatic dispersion for radiation emitted from the chromatic point sensor optical pen, and that receives radiation reflected from the surface

Methodology Applied
Scientific EffectLongitudinal chromatic dispersion: Dispersion (of waves)

Implementation Method 2

an aperture element that is fixed relative to the mounting element such that a surface of the aperture element is inclined at an angle T1 relative to a plane that is normal to an axis of the hole, the aperture element providing an aperture fixed at an aperture operating position relative to the optical element portion

Methodology Applied
Scientific EffectGeometric optics aperture constraint:

Data Source

PatentEP1975551B1Chromatic confocal sensor fiber interface
Publication Date: 2010.11.03 MITUTOYO CORP
  • EP1975551B1 patent drawingFigure 1
  • EP1975551B1 patent drawingFigure 2
  • EP1975551B1 patent drawingFigure 3

AI summary

A fiber interface configuration (100) for a chromatic point sensor optical pen is provided wherein a detector aperture element (190) provides an aperture that is smaller than the light-transmitting core diameter of an optical fiber (112) that is connected to the optical pen. The detector aperture element (190) is fixed relative to the chromatically dispersive optics of the optical pen, the optical fiber (112) abuts the aperture element, and the optical fiber core is aligned to the aperture. The aperture element (190) and the end of the fiber (112) may be inclined relative to the axis of the fiber, to deflect spurious reflections away from the optical signal path. The configuration provides high measuring resolution without using a tapered optical fiber, and provides interchangeability of the optical fiber connected to the optical pen.