Terahertz Characterization of Layered Materials Using Machine Learning
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Solution Overview
Problem
Current methods for measuring the thickness and other properties of layered coatings using terahertz radiation face challenges such as requiring contact, limited resolution, inability to measure individual layers, and the need for calibration, which are time-consuming and prone to errors, especially when dealing with varying materials.
Innovation Solution
A method utilizing machine learning algorithms to process terahertz-reflected signals from layered materials, allowing for contactless measurement of thickness and other parameters like adherence without the need for calibration, using a measuring system with a terahertz emitter and detector integrated with a control unit and optical system for focused beam guidance, enabling compact and efficient characterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional terahertz measurement methods are used, then thickness measurement is achieved, but calibration steps are required which are time-consuming and prone to errors
Solution Approach 1:
The system performs preliminary calibration by storing reference terahertz signals from known reference layers in a database before actual measurement. This pre-stored reference data eliminates the need for time-consuming calibration steps during operation, as the system directly compares measured signals against the pre-established reference library.
Solution Approach 2:
The invention creates a digital copy of reference layer characteristics by storing terahertz signals from known reference layers in a database. This digital replica allows direct comparison with measured signals without requiring physical calibration standards or repeated calibration procedures.
2Ease of operation
If terahertz waves are used for thickness measurement, then contactless measurement is achieved, but reflected pulses show significant overlap when layers are very thin making time difference measurement challenging
Solution Approach 1:
The system introduces an intermediary reference layer with known characteristics between the measurement process and the target sample. By comparing the terahertz signal reflections from the sample against the pre-stored reference signal, the system indirectly determines layer thickness without needing to directly resolve overlapping reflection pulses from thin layers.
Solution Approach 2:
The invention transforms the measurement approach by changing from direct time-domain analysis of overlapping pulses to a database-matching approach where the entire signal waveform (including overlapping components) is compared against reference signals. This parameter transformation allows accurate thickness measurement even when individual pulse components cannot be clearly distinguished.
3Reliability
If emitter and detector are positioned away from each other with inclined axes, then reflected THz beam can be received, but the measuring system becomes bulky and inconvenient to use
Solution Approach 1:
The invention merges the emitter and detector into a single integrated measuring head unit. This combined design eliminates the need for separate positioning of emitter and detector with inclined axes, significantly reducing system size and complexity while maintaining the capability to receive reflected THz beams through the integrated architecture.
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 approach provides reliable, efficient, and robust characterization of layered materials, reducing measurement time and experimental errors, and accommodating variations in material composition and construction, enhancing manufacturing flexibility.
Implementation Method 1
A portable device for measuring the thickness of a coating on a substrate comprises a portable terahertz emitter arranged to emit a pulse of terahertz radiation towards the coating
Implementation Method 2
As a pulse of THz waves travels through the layers, reflections (or echoes) will be generated at the interfaces between different index of refraction
Implementation Method 3
reflections are a function of both structural and chemical properties of the material such as changes in the index of refraction in the different layers
Implementation Method 4
a portable terahertz detector arranged to detect at least part of the reflected pulse of terahertz radiation from the coating
Data Source
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AI summary
A method for characterising a material with a layered structure using terahertz A method for characterising a material with a layered structure using terahertz radiation comprising determining characterising information of the material with layered structure by implementing a machine learning approach and a measuring system for obtaining characterising information of such material with a layered structure, the measuring system comprising a terahertz emitter associated with a laser light source and adapted to generate a THz-emitted beam to be irradiated on the material, a terahertz detector associated with the laser light source and adapted to detect a THz-reflected beam from the material, and an optical system designed to guide and focus the THz-emitted beam on the material and to guide and collect the THz-reflected beam from the material.