Surface Contamination Detection via Laser Desorption

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Solution Overview

Problem

Existing methods fail to effectively detect and differentiate release agent residues on fiber-reinforced plastics, particularly due to their low concentrations and small layer thickness, which can contaminate surfaces and affect structural bonding processes.

Innovation Solution

A device and method using a radiation source to convert non-volatile substances into gas for detection, with a measuring bell and detector unit to quantify contaminants, and a process monitoring unit to control temperature and prevent thermal damage, allowing for the detection of low-volatility substances and their decomposition products.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct measurement of contamination is performed on the surface, then the contamination layer can be examined, but the measurement is problematic due to the very small layer thickness

Engineering Contradiction:
Improvecontamination detection capabilityVSAvoidmeasurement difficulty due to small layer thickness
Core Design Contradiction:
Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies phase transition by heating the sample surface to convert non-volatile contamination substances from solid/liquid state into gas phase. This phase change enables the contaminants to be desorbed from the surface and detected by gas-phase sensors, overcoming the limitation of direct surface measurement for extremely thin contamination layers.

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The patent introduces a measuring bell as an intermediary component that creates a controlled measurement volume between the sample surface and the detector. This intermediary structure allows the desorbed gas-phase contaminants to be collected and concentrated before detection, enhancing the measurement capability for trace contamination.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If laser-induced plasma spectroscopy is used to detect silicone contamination, then chemical element detection is possible, but it cannot distinguish between silicones and silicates

Engineering Contradiction:
Improvechemical element detection capabilityVSAvoidinability to distinguish between silicones and silicates
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The patent changes the detection parameter from elemental composition (which cannot distinguish silicones from silicates) to molecular structure information. By using FTIR spectroscopy to detect the infrared absorption spectra of the desorbed gases, the system can identify specific molecular bonds and functional groups, enabling differentiation between silicone compounds and silicate compounds based on their unique spectral fingerprints.

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If FTIR spectrometer is used for analysis, then molecular structure detection is possible, but the technique cannot detect release agent residues due to low concentrations

Engineering Contradiction:
Improvemolecular structure detection capabilityVSAvoiddetectability at low concentrations
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent applies preliminary action by heating the sample surface before FTIR detection to desorb the contamination substances from the surface into the gas phase. This pre-concentration step in the measuring bell volume increases the effective concentration of analytes reaching the FTIR detector, enabling detection of release agent residues that would otherwise be below the detection limit.

Inventive Principle:
Principle #10Preliminary action

4Measurement precision

If surface heating is applied to desorb contaminants for detection, then gas-phase detection sensitivity is improved, but thermal damage to the sample surface may occur

Engineering Contradiction:
Improvegas-phase detection sensitivityVSAvoidthermal damage risk to sample surface
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent implements feedback control by continuously monitoring the temperature at the sample surface during the heating process. The temperature information is fed back to the control system, which adjusts the heating power in real-time to maintain the temperature within a safe range that enables contaminant desorption without causing thermal damage to the fiber-reinforced plastic sample.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent applies periodic action by using pulsed or cyclic heating instead of continuous heating. This allows the sample surface to be heated to desorption temperatures for short intervals, followed by cooling periods, thereby achieving effective contaminant release while limiting the total thermal exposure and preventing cumulative thermal damage to the sample.

Inventive Principle:
Principle #19Periodic 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 the detection of non-volatile contaminants, including release agent residues, in a material-friendly manner, even at low concentrations, improving the assessment of component surfaces for processing suitability and allowing for simultaneous surface cleaning and activation.

Implementation Method 1

a radiation source which is set up to at least partially convert at least one non-volatile substance into gas by irradiating a sample surface

Methodology Applied
Scientific EffectIrradiation-induced phase conversion: Laser Ablation

Implementation Method 2

a detector unit which is set up to qualitatively and/or quantitatively detect the at least one substance that has been converted into gas

Methodology Applied
Scientific EffectGas phase detection: Absorption Spectroscopy

Implementation Method 3

a process monitoring unit which is set up to detect a temperature prevailing on the sample surface

Methodology Applied
Scientific EffectTemperature monitoring: Thermography

Implementation Method 4

the radiation source includes a controller which is set up to compare the detected temperature with a predetermined threshold value, which implies a risk of thermal damage to the sample surface and to end the irradiation or to reduce the intensity if the temperature exceeds the threshold value

Methodology Applied
Scientific EffectThermal protection control: Thermal Shock

Implementation Method 5

The radiation source is set up to remove any material removed from the fiber-reinforced plastic component from the sample surface

Methodology Applied
Scientific EffectMaterial removal through irradiation: Ablation

Data Source

PatentEP3093644B1Investigation of the surfaces of components
Publication Date: 2019.09.18 AIRBUS DEFENCE & SPACE GMBH
  • EP3093644B1 patent drawingFigure 1~2

AI summary

A device (1) according to the invention is used for surface testing of components. It comprises: a radiation source (12) configured to convert at least one semi-volatile substance (22a) at least partially into a gas by irradiating a sample area (100) of a component (20); and a detector unit (15) configured to qualitatively and/or quantitatively detect the at least one substance (22b, 22c, 23) converted into a gas. A method according to the invention is used for surface testing of components. It comprises irradiating a sample area (100) of a component (20) with a radiation source (12) configured to convert at least one semi-volatile substance (22a) at least partially into a gas; and qualitatively and/or quantitatively detecting the at least one substance (22b, 22c, 23) converted into a gas by means of a detector unit (15).