Terahertz Coating Microstructure Inspection via Oblique Pulse Reflection
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Solution Overview
Problem
Existing methods for determining the microstructure of thermal barrier coatings are time-consuming and expensive, and they struggle to efficiently assess the microstructure of coatings on substrates without causing damage.
Innovation Solution
A non-destructive inspection system using terahertz frequency electromagnetic pulses directed at an oblique angle to the coating surface, which measures the time delay between reflections from the coating and substrate surfaces to assess the coating's microstructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods are used to determine coating microstructure, then measurement precision is achieved, but inspection time and cost increase significantly
Solution Approach 1:
The patent replaces conventional mechanical inspection methods with terahertz electromagnetic wave-based non-contact inspection. The system uses a terahertz time-domain reflectometer to send electromagnetic pulses through the coating and detect reflections from the substrate interface, enabling rapid microstructure assessment without physical contact or destructive sampling.
Solution Approach 2:
The patent utilizes the frequency-dependent penetration depth of terahertz waves as a key parameter. By analyzing how different frequency components of the electromagnetic pulse penetrate and reflect from the coating-substrate interface, the system can rapidly determine coating thickness and microstructure characteristics without time-consuming physical measurement.
2Measurement precision
If conventional inspection methods are applied, then coating microstructure can be assessed, but the coating may be damaged or scratched
Solution Approach 1:
The patent replaces mechanical inspection methods with non-contact electromagnetic wave-based inspection. The terahertz time-domain reflectometer sends electromagnetic pulses through the coating and detects reflections from the substrate interface, enabling rapid microstructure assessment without physical contact or destructive sampling.
Solution Approach 2:
The patent uses terahertz electromagnetic waves as an intermediary to transmit information about the coating microstructure without direct physical contact. The electromagnetic waves penetrate the coating and interact with the substrate interface, providing measurement data while leaving the coating undamaged.
3Measurement precision
If multiple coating layers are inspected, then comprehensive microstructure assessment is achieved, but detection complexity increases
Solution Approach 1:
The patent segments the electromagnetic pulse into different frequency components, each with distinct penetration depths. By analyzing the reflection characteristics of these segmented frequency components from different coating layers, the system can resolve and assess multiple coating layers individually without requiring complex multi-frequency instrumentation.
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 system enables fast, efficient, and non-destructive assessment of coating microstructures, distinguishing between anisotropic and isotropic microstructures, and can be used for real-time monitoring of coating conditions.
Implementation Method 1
a terahertz light source to emit a train of electromagnetic pulses towards the sample
Implementation Method 2
measuring a time delay between the electromagnetic pulses and reflected electromagnetic pulses from the sample
Implementation Method 3
a fast rotating translational platform. The terahertz QWP can rapidly detect the THz radiation generated from a pulsed electrically pumped terahertz quantum cascade laser
Implementation Method 4
directing the electromagnetic pulses at an oblique angle relative to a surface of the coating
Data Source
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Figure 3
Figure 4~5
AI summary
A system (100) for inspecting a coating (112) on a substrate (110), the system (100) including a platform (102) that receives a sample (108) including the substrate (110) having the coating (112), and a light source (104) that directs a plurality of electromagnetic pulses (114) towards a scanning location (116) on the coating (112), wherein the light source (104) is oriented to direct the plurality of electromagnetic pulses (114) at an oblique angle (θ) relative to a surface (118) of the coating (112). A light detector (106) receives electromagnetic pulses (114) reflected from the sample (108), wherein a first portion (142) of each electromagnetic pulse (114) is reflected from the surface (118) of the coating (112), and a second portion (144) of each electromagnetic pulse (114) is reflected from a surface (118) of the substrate (110). An actuator (124) is coupled to the platform (102) and/or the light source (104), wherein the actuator (124) moves the platform (102) and the light source (104) relative to each other such that the plurality of electromagnetic pulses (114) are directable towards the scanning location (116) from different rotational positions.