Fluorescence Surface Inspection via Free-Flying Object Motion

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Solution Overview

Problem

Existing surface testing methods require complex handling and positioning of test objects, which is inefficient and labor-intensive, especially when testing products with low intrinsic fluorescence and high-speed movement.

Innovation Solution

A method where the test object flies freely on an object test track, allowing for illumination and detection of fluorescence from multiple spatial directions using a high-intensity lighting unit and sensitive detection system, enabling efficient analysis of coating thickness and contamination distribution without the need for complex handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the test object is illuminated with high light intensity to excite low autofluorescence, then detection sensitivity is improved, but the object moves quickly making it difficult to capture sufficient fluorescence signal

Engineering Contradiction:
Improvedetection sensitivityVSAvoidobject movement speed
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The patent employs pulsed illumination instead of continuous illumination to excite fluorescence. The illumination unit emits light in periodic pulses synchronized with the object's movement, allowing accumulation of fluorescence signals over multiple pulses while maintaining high detection sensitivity. This periodic action resolves the contradiction by enabling sufficient signal accumulation despite the object's high speed movement.

Inventive Principle:
Principle #19Periodic action

2Measurement precision

If the test object is inspected from multiple sides, then measurement completeness is improved, but handling and positioning complexity increases

Engineering Contradiction:
Improvemeasurement completenessVSAvoidhandling complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of moving the illumination and detection units to inspect the object from multiple sides, the patent inverts the approach by keeping the illumination and detection units stationary and allowing the test object to move freely past them. The object passes through the inspection zone multiple times from different orientations, enabling complete multi-sided inspection without complex handling mechanisms.

Inventive Principle:
Principle #13The other way round (Inversion)

3Measurement precision

If short exposure times are used to capture moving objects, then spatial resolution is improved, but the integration time for detecting fluorescence radiation becomes insufficient

Engineering Contradiction:
Improvespatial resolutionVSAvoidintegration time
Core Design Contradiction:
Measurement precisionVSDuration of action of moving object

Solution Approach 1:

The system performs preliminary synchronization between the pulsed illumination and the camera exposure timing. The illumination pulses are timed to coincide with the object's position in the inspection zone, and the camera exposure is pre-synchronized to capture fluorescence during these pulses. This preliminary coordination allows sufficient integration time for fluorescence detection while maintaining short effective exposure times for high spatial resolution.

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

Enables rapid, efficient testing of test objects from multiple sides with high spatial resolution, reducing handling efforts and improving detection sensitivity and accuracy, even for products with low intrinsic fluorescence and high-speed movement.

Implementation Method 1

the autofluorescence of a desired or undesired substance on a test object's surface is first excited using UV light

Methodology Applied
Scientific EffectFluorescence excitation: Fluorescence

Implementation Method 2

the emitted fluorescence radiation is then visualized

Methodology Applied
Scientific EffectFluorescence emission: Fluorescence

Data Source

PatentEP3640628B1Method for testing the surface of an object
Publication Date: 2024.03.06 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP3640628B1 patent drawingFigure 1
  • EP3640628B1 patent drawingFigure 2
  • EP3640628B1 patent drawingFigure 3

AI summary

The present invention relates to a system for inspecting the surface of a test object, comprising: an object inspection section, an object illumination unit configured and arranged such that, during operation of the system, it illuminates the test object on the object inspection section with electromagnetic excitation radiation of a first wavelength, and an object detection unit configured and arranged such that, during operation of the system, it detects electromagnetic luminescence radiation emitted by the test object with a second wavelength different from the first, generates object data, and outputs it. It is an object of the present invention to provide such a system which does not require complex handling for positioning the test object.To solve this problem, it is proposed that in the system described above, the object illumination unit is set up and arranged in such a way that it illuminates the test object from a plurality of spatial directions, the object detection unit is set up and arranged in such a way that it detects the luminescence radiation from the test object in a plurality of spatial directions, and the object test path is a flight path, wherein the system is set up and arranged in such a way that the test object flies along the object test path during the operation of the system.