Nondestructive thermographic detection of internal defects using pixel-pattern based laser excitation and photothermal super resolution reconstruction

Lecompagnon, Julien; Hirsch, Philipp Daniel; Rupprecht, Christian; Ziegler, Mathias

doi:10.1038/s41598-023-30494-2

Cited by 8 publications

(2 citation statements)

References 25 publications

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“…In 23 , a DMD projector (optical output power = 85 W) was used to perform thermal super-resolution measurements through 2D projected patterns on metal specimens, enabling precise feature detection. However, this method was time-consuming.…”

Section: Fundamentals Of Signal Formation and Structured Heatingmentioning

confidence: 99%

Lateral heat flux reduction using a lock-in thermography compensation method

Rittmann,

Kreutzbruck

2023

Sci Rep

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The naturally diffusive heat flow in solids often results in differences in surface temperatures. Active thermography (AT) exploits such differences to gain information on the internal structure, morphology, or geometry of technical components or biological specimens. In contrast to sound or light waves, thermal waves are lossy; consequently, it is difficult to interpret measured 2D temperature fields. Most AT evaluation methods are based on 1D approaches, and measured 3D heat fluxes are frequently not considered, which is why edges, small features, or gradients are often blurred. Herein, we present a method for reducing the local temperature gradients at feature areas and minimizing the induced lateral heat flux in optical lock-in thermography (LT) measurements through spatial- and temporal-structured heating. The vanishing lateral gradients convert the problem into a 1D problem, which can be adequately solved by the LT approach. The proposed compensation method can bypass the blind frequency of LT and make the inspection largely independent of the excitation frequency. Furthermore, the edge sharpness and separability of features are improved, ultimately improving the feature-detection efficiency.

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Section: Fundamentals Of Signal Formation and Structured Heatingmentioning

confidence: 99%

Lateral heat flux reduction using a lock-in thermography compensation method

Rittmann,

Kreutzbruck

2023

Sci Rep

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“…As a first demonstration, we show its ability to measure the cross-plane thermal conductivity of microscope glass slides. Owing to the flexibility that comes with pixelated heating, beyond measuring thermal conductivity, the same setup can be integrated with other DLP-projector based techniques to include functionalities like non-destructive testing [6] .…”

Section: Introductionmentioning

confidence: 99%

Structured illumination with infrared imaging for measuring thermal conductivity

Bhat,

Dames

2024

J. Phys.: Conf. Ser.

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With developments in advanced manufacturing and materials by design comes the need for high-throughput thermal characterization and inspection. Towards this end, Structured Illumination with Thermal Imaging (SITI) is an all-optical pump-probe thermal characterization technique recently developed by our group. In the first generation [Zheng et al., Appl. Phys. Rev. 9, 021411 (2022)] SITI uses an LED with a digital micromirror device (DMD) to “structurally illuminate” and heat the sample with dynamic patterns, a visible light camera for thermoreflectance based “thermal imaging” [leveraging a Microsanj MTIR120], and the resultant temperature response was fit with a thermal model to characterize the sample’s thermal properties. This represents a novel approach to dynamic and flexible spatial mapping of thermal properties by virtue of being a non-contact technique and having a simpler scanning means (computer control only) than conventional pump-probe laser methods. SITI also can tolerate rough samples with diffuse reflections. This talk presents the second generation of SITI. The pumping is now based on a lower cost off-the-shelf digital projector. The thermometry is now performed using an infrared (IR) camera, which we find is a more flexible and accessible hardware approach compared to the thermoreflectance microscopy used previously. With these updates the setup can deliver higher heating power and a broader range of frequencies, allowing an extended range of samples that can be studied. We have demonstrated SITI’s ability to measure the thermal conductivity of a microscope glass slide.

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One-dimensional N-layer thermal modelling for effective machine learning training data generation for nondestructive testing of composite parts with infrared thermography

Yagdjian,

Gurka

2025

Composites Part B: Engineering

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Nondestructive thermographic detection of internal defects using pixel-pattern based laser excitation and photothermal super resolution reconstruction

Cited by 8 publications

References 25 publications

Lateral heat flux reduction using a lock-in thermography compensation method

Lateral heat flux reduction using a lock-in thermography compensation method

Structured illumination with infrared imaging for measuring thermal conductivity

One-dimensional N-layer thermal modelling for effective machine learning training data generation for nondestructive testing of composite parts with infrared thermography

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