Nondestructive testing by using long-wave infrared interferometric techniques with CO2 lasers and microbolometer...

Area of Science:

• Optical Engineering
• Materials Science
• Non-Destructive Testing

Background:

• Interferometric techniques are crucial for high-sensitivity measurements.
• Long-wave infrared (LWIR) radiation offers unique material penetration and thermal imaging capabilities.
• Microbolometer arrays provide sensitive detection for infrared applications.

Purpose of the Study:

• To investigate and compare three interferometric methods using LWIR radiation for non-destructive testing (NDT).
• To demonstrate the application of electronic speckle pattern interferometry, digital holographic interferometry, and digital shearography in NDT.
• To evaluate the advantages and disadvantages of each technique for practical NDT applications.

Main Methods:

• Utilized a CO(2) laser to generate long-wave infrared radiation.
• Employed three distinct interferometric techniques: electronic speckle pattern interferometry (ESPI), digital holographic interferometry (DHI), and digital shearography.
• Recorded infrared radiation using a microbolometer array for data acquisition.

Main Results:

• Experimental results demonstrated the feasibility of using LWIR-based ESPI, DHI, and shearography for non-destructive testing.
• The techniques successfully identified surface and subsurface defects through interferometric analysis of thermal deformation.
• Comparative analysis highlighted the specific strengths and limitations of each method in different NDT scenarios.

Conclusions:

• LWIR-based interferometric techniques offer a viable approach for non-destructive testing.
• The choice of technique (ESPI, DHI, shearography) depends on the specific NDT requirements, such as defect type and material.
• Further development can enhance the sensitivity and applicability of these infrared interferometric methods for industrial inspection.