Photo-acoustic Tomography Defect Testing System
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Solution Overview
Problem
Existing non-destructive testing methods for detecting sub-surface defects in parts using photo-acoustic tomography are complex, expensive, and time-consuming, requiring substantial setup and processing time.
Innovation Solution
A part defect testing method utilizing a system that generates a hammer beam and a read-out beam using laser light of different wavelengths, directing the hammer beam to induce surface movement and using the read-out beam with an areal camera to produce an interferogram, which is then processed to detect defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional photo-acoustic tomography testing systems are used, then defect detection capability is achieved, but system complexity and operational cost increase substantially
Solution Approach 1:
The patent extracts and eliminates the complex Michelson interferometer component from the traditional photo-acoustic tomography system. By removing this intricate interferometric setup, the system achieves simplified architecture while maintaining defect detection capability through alternative optical measurement approaches
Solution Approach 2:
The patent replaces the mechanical interferometric measurement system with a simplified optical detection system. Instead of using mechanical interferometers to measure surface oscillations, the system employs direct optical detection methods that reduce mechanical complexity while preserving measurement functionality
2Measurement precision
If traditional photo-acoustic tomography testing systems are used, then defect detection capability is achieved, but operational cost increases substantially
Solution Approach 1:
The patent employs inexpensive optical components and simplified detection mechanisms替代 expensive interferometric equipment. By using affordable optical sensors and straightforward measurement systems, the operational cost is substantially reduced while maintaining adequate defect detection precision
3Measurement precision
If traditional photo-acoustic tomography testing systems are used, then defect detection capability is achieved, but scanning time increases substantially
Solution Approach 1:
The patent enables continuous optical measurement across the part surface without interruption. By maintaining continuous optical detection during the scanning process, the system eliminates idle time between measurements and substantially reduces total scanning time while preserving defect detection accuracy
Solution Approach 2:
The patent employs periodic optical pulsing synchronized with acoustic wave detection cycles. This periodic measurement approach allows efficient data collection at optimal moments during acoustic wave propagation, reducing overall scanning time while maintaining measurement precision
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 method allows for efficient and accurate detection of sub-surface defects in parts by reducing complexity and cost, while also significantly reducing the time required for scanning and defect analysis.
Implementation Method 1
A short pulse laser (i.e. a hammer or ping pulse) is directed incident onto the surface of the PUT to locally heat the surface of the PUT during the pulse width of the laser pulse. This launches an acoustic pulse into the PUT as a result of differential heating, plasma generation or local expansion
Implementation Method 2
The acoustic response is launched, causing the surfaces of the PUT to minutely move. This motion causes a phase modulation on the read-out beam which can be detected by taking the reflection of the read-out beam and processing it through a Michelson interferometer
Data Source
Figure 1A~1B
Figure 1C
Figure 1D
AI summary
A part defect testing system includes a hammer beam system that provides laser light having a first wavelength. A read-out beam system provides laser light having a second wavelength. A control system is used to direct the generated hammer beam laser light toward a first position on a part to provide an acoustic hammer pulse that induces surface movement of the part. An areal camera is arranged to produce an interferogram derived from reading surface movement of the part using the read-out beam directed to a second position on the part.