Optical Gear Measurement Light Source for Stable Confocal Accuracy

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Solution Overview

Problem

Optical measurement of gear teeth is challenging due to their geometry, high reflectivity, and environmental factors like contamination, vibrations, and temperature fluctuations, which complicate achieving optimal probing angles and affect measurement accuracy and reproducibility.

Innovation Solution

A coordinate measuring machine equipped with an optical distance sensor and a light source that includes a broadband light-emitting material, active temperature control, and active light intensity control, combined with a light guide and optics, to provide a stable and spectrally homogeneous light source for improved gear measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If optical measurement systems are used for gear metrology, then measurement time is reduced compared to tactile systems, but measurement accuracy and reproducibility deteriorate due to gear geometry, surface reflectivity, and environmental factors

Engineering Contradiction:
Improvemeasurement speedVSAvoidmeasurement accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent changes the spectral parameters of the light source by using a broadband light source (400-700nm) instead of conventional narrowband sources. This parameter change enables better differentiation of optical path differences and improves measurement accuracy while maintaining fast measurement speeds through the optical confocal sensor system

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements active temperature control of the light source to dynamically compensate for thermal effects during measurement. This dynamic stabilization maintains consistent optical properties despite environmental temperature variations, improving both accuracy and reproducibility across different measurement conditions

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If conventional light sources are used in optical measurement systems, then device complexity is low, but measurement accuracy deteriorates due to insufficient spectral homogeneity and intensity stability

Engineering Contradiction:
Improveoptical measurement accuracyVSAvoidlight source complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces a light guide as an intermediary component to deliver the broadband light from the source to the optical confocal sensor. This intermediary enables precise light delivery and coupling, improving measurement accuracy while allowing the light source to be positioned separately from the sensor head

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent implements active feedback control systems for both temperature and light intensity. The temperature control unit continuously monitors and adjusts the light source temperature, while the intensity control unit maintains stable output. These feedback mechanisms improve measurement consistency and accuracy despite the increased device complexity

Inventive Principle:
Principle #23Feedback

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

The solution achieves improved measurement accuracy and reproducibility in optical gear measurement by ensuring a stable, broadband, and spectrally homogeneous light source, enhancing the measurement speed and quality.

Implementation Method 1

a light source applied to a carrier board, which light source comprises a material that emits broadband light when excited, such as phosphor or the like, a laser for exciting the light source by means of laser light

Methodology Applied
Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

an optic and a light guide, wherein the optic is configured to focus the source light into the light guide

Methodology Applied
Scientific EffectOptical focusing: Focusing

Implementation Method 3

the light guide is coupled to the optical distance sensor

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP4365539B1Coordinate measuring machine and method for operating said coordinate measuring machine
Publication Date: 2026.05.20 KLINGELNBERG GMBH
  • EP4365539B1 patent drawingFigure 1
  • EP4365539B1 patent drawingFigure 2

AI summary

Coordinate measuring machine, with two or more linear axes (x, y, z), with at least one rotational axis (C), with an optical distance sensor (4) for detecting measuring points on a workpiece (6) to be measured, and with a light source (10), wherein the linear axes (x, y, z) and the rotational axis (C) are configured to perform relative movements between the workpiece (6) to be measured and the optical distance sensor (4), wherein the light source (10) is configured to provide source light (11) for the optical distance sensor (4), and wherein the light source (10) comprises: a light source (14) mounted on a carrier board (12), which has a material that emits broadband light when excited, such as phosphor or the like, a laser (18) for exciting the light source (14) by means of laser light (20), and a device (22) for actively controlling the luminous intensity of the source light (11) generated by the light source (10).a device (24) for actively controlling a temperature within the light source (10), an optic (26) and an optical fiber (28), wherein the optic (26) is configured to focus the source light (11) into the optical fiber (28) and wherein the optical fiber (28) is coupled to the optical distance sensor (4).