1. Articles in category: NDE/NDT

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    1. In-process monitoring in laser grooving with line-shaped femtosecond pulses using optical coherence tomography

      In-process monitoring in laser grooving with line-shaped femtosecond pulses using optical coherence tomography

      A line-shaped beam is useful for increasing the processing speed in laser grooving and scribing. In laser grooving, depth control of the processed structure is important for performing precise processing. In this paper, in-process monitoring of the depth of a structure formed by femtosecond laser processing with a line-shaped beam using swept-source optical coherence tomography (SS-OCT) was demonstrated. In the evaluation of the SS-OCT system, the depth resolution, measurement accuracy, and axial measurable range were 15.8 μm, ±2.5 μm and 5.3 mm, respectively. In laser grooving, the structural shape and the distribution of deposited debris were successfully ...

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    2. Method and device for contactless and non-destructive determination of the layer thicknesses of lacquer layers of vehicle parts

      Method and device for contactless and non-destructive determination of the layer thicknesses of lacquer layers of vehicle parts

      A method for contactless and non-destructive determination of the layer thicknesses of lacquer layers of vehicle parts is disclosed. In addition, the invention relates to a device to determine and measure the lacquer layers of vehicle part, the device constructed for performing optical coherence tomography and includes at least one radiation source for providing electromagnetic radiation and the electromagnetic radiation provides a wavelength (.lamda.)

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    3. Identification of Fungus-infected Tomato Seeds Based on Full-Field Optical Coherence Tomography

      Identification of Fungus-infected Tomato Seeds Based on Full-Field Optical Coherence Tomography

      The morphological changes of anthracnose (fungus) -infected tomato seeds have been studied to identify the infection and characterize its effect. Full-field optical coherence tomography (FF-OCT) has been utilized as a nondestructive but efficient modality for visualizing the effects of fungal infection. The cross-sectional images extracted from a stack of en face FF-OCT images showed significant changes with infection in the seed structure. First of all, the seed coat disappeared with the infection. The thickness of the seed coat of a healthy seed was measured as 28.2 ㎛, with a standard deviation of 1.2 ㎛. However, for infected seeds the gap ...

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    4. Project Team Become Third Place Finalists for the Innovation Award Laser Technology 2022 - OCT process monitoring for on-the-fly laser welding and additive manufacturing impresses the jury

      Project Team Become Third Place Finalists for the Innovation Award Laser Technology 2022 - OCT process monitoring for on-the-fly laser welding and additive manufacturing impresses the jury

      A team from the sister companies Blackbird Robotersysteme GmbH and SCANLAB GmbH submitted a joint solution for the Innovation Award Laser Technology 2022. On May 4, the project team was awarded third place for its innovative scan solution with integrated OCT process monitoring. The system primarily impresses due to its flexibility and high practical suitability for the automotive sector. The ability to synchronize scanner and sensor data developed in-house also enables use in other application areas such as additive manufacturing. The renowned prize is awarded by the associations AKL Arbeitskreis Lasertechnik e.V. and the ELI (European Laser Institute) at ...

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    5. Optical Coherence Tomography Ensures Quality of Thin Films

      Optical Coherence Tomography Ensures Quality of Thin Films

      The Fraunhofer Institute for Production Technology IPT in Aachen, Germany, has developed an interferometric measurement method that can be used to reliably measure whether thin transparent layers of paint have been applied evenly: The possibilities offered by optical coherence tomography (OCT) for measuring such paint layers will be presented at CONTROL 2022 by the Fraunhofer IPT using a prototype.

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    6. Control 2022: Optical coherence tomography ensures the quality of thin films

      Control 2022: Optical coherence tomography ensures the quality of thin films

      From high-gloss brochures to new cars: paint layers that are also supposed to shine in front of customers must be smooth and even to reflect perfect quality. The Fraunhofer Institute for Production Technology IPT in Aachen, Germany, has developed an interferometric measurement method that can be used to reliably measure whether thin transparent layers of paint have been applied evenly: The possibilities offered by optical coherence tomography (OCT) for measuring such paint layers will be presented to the trade fair public by the Fraunhofer IPT using a prototype at Control, the leading international trade fair for quality assurance from May ...

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    7. Differentiating fouling on the membrane and on the spacer in low-pressure reverse-osmosis under high organic load using optical coherence tomography

      Differentiating fouling on the membrane and on the spacer in low-pressure reverse-osmosis under high organic load using optical coherence tomography

      The understanding of fouling mechanisms makes it possible to develop controlling strategies to optimize membrane performance. In this work, optical coherence tomography (OCT) was used for in-situ characterization of biomass occluding the feed channels of low-pressure reverse-osmosis membrane modules used to treat a feed stream with high organic load. A method for differentiating fouling formation on the membrane itself and on the spacer using two parameters ( ME, for the membrane and SP, for the spacer) was developed. Pressure drop along the module and flux were measured at constant inlet pressure and then confronted with ME and SP . Pressure drop increased ...

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    8. Ascertain a Minimum Coating Thickness for Acid Protection of Enteric Coatings by Means of Optical Coherence Tomography

      Ascertain a Minimum Coating Thickness for Acid Protection of Enteric Coatings by Means of Optical Coherence Tomography

      Enteric coatings are designed to protect active pharmaceutical ingredients (APIs) against untimely release in the stomach. Acid protection of such coatings depends on the coating layer thickness and integrity, which must be determined in an accurate and reliable way to ensure the final product's desired performance. Our work addresses the use of optical coherence tomography (OCT) for characterizing the coating thickness and variability of an enteric-coated drug product, linking them to resistance against gastric fluid. In this study, three batches of enteric-coated tablets drawn during the manufacturing process were investigated. An industrial OCT system was used to establish the ...

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    9. Textural Feature Analysis of Optical Coherence Tomography Phantoms

      Textural Feature Analysis of Optical Coherence Tomography Phantoms

      Optical coherence tomography (OCT) is an imaging technique based on interferometry of backscattered lights from materials and biological samples. For the quantitative evaluation of an OCT system, artificial optical samples or phantoms are commonly used. They mimic the structure of biological tissues and can provide a quality standard for comparison within and across devices. Phantoms contain medium matrix and scattering particles within the dimension range of target biological structures such as the retina. The aim was to determine if changes in speckle derived optical texture could be employed to classify the OCT phantoms based on their structural composition. Four groups ...

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    10. Non-Contact Paper Thickness and Quality Monitoring Based on Mid-Infrared Optical Coherence Tomography and THz Time Domain Spectroscopy

      Non-Contact Paper Thickness and Quality Monitoring Based on Mid-Infrared Optical Coherence Tomography and THz Time Domain Spectroscopy

      Abstract: In industrial paper production, online monitoring of a range of quality parameters is essential for ensuring that the performance and appearance of the final product is suitable for a given application. In this article, two optical sensing techniques are investigated for non-destructive, non-contact characterization of paper thickness, surface roughness, and production defects. The first technique is optical coherence tomography based on a mid-infrared supercontinuum laser, which can cover thicknesses from ~20–90 μ m and provide information about the surface finish. Detection of subsurface voids, cuts, and oil contamination was also demonstrated. The second technique is terahertz time domain spectroscopy ...

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    11. Optical Coherence Tomography Improves LMD Process Stability

      Optical Coherence Tomography Improves LMD Process Stability

      Process stability and control are of great importance in laser metal deposition: Ideally, abnormalities and deviations in the process must be immediately addressed without delay to prevent interrupting the process. This is where systems for machine-integrated monitoring are needed – they can check such processes directly on the spot and initiate corrections. Together with its industrial and research partners, the Fraunhofer Institute for Production Technology IPT has, therefore, integrated the imaging inspection method optical coherence tomography (OCT) into a coaxial process for wire-based laser metal deposition, or LMD-w. The new OCT measurement methodology can not only record the welding process in ...

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    12. Optical coherence tomography improves process stability of laser metal deposition

      Optical coherence tomography improves process stability of laser metal deposition

      Process stability and control are of great importance in laser metal deposition: Ideally, abnormalities and deviations in the process must be immediately addressed without delay to prevent interrupting the process. This is where systems for machine-integrated monitoring are needed - they can check such processes directly on the spot and initiate corrections. Together with its industrial and research partners, the Fraunhofer Institute for Production Technology IPT has, therefore, integrated the imaging inspection method optical coherence tomography (OCT) into a coaxial process for wire-based laser metal deposition, or LMD-w. The new OCT measurement methodology can not only record the welding process in ...

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    13. Non-destructive mapping of stress, strain and stiffness of thin elastically deformed materials

      Non-destructive mapping of stress, strain and stiffness of thin elastically deformed materials

      Knowing the stress within a soft material is of fundamental interest to basic research and practical applications, such as soft matter devices, biomaterial engineering, and medical sciences. However, it is challenging to measure stress fields in situ in a non-invasive way. It becomes even more difficult if the mechanical properties of the material are unknown or altered by the stress. Here we present a robust non-destructive technique capable of measuring in situ stress and strain in elastically deformed thin films without the need to know their material properties. The technique is based on measuring elastic wave speeds, and then using ...

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    14. Comparing different methods to measure biofilm thickness: the techniques are: optical coherence tomography, confocal laser scanning microscopy and low load compression test (Thesis)

      Comparing different methods to measure biofilm thickness: the techniques are: optical coherence tomography, confocal laser scanning microscopy and low load compression test (Thesis)

      Biofilm formation remains a serious concern in industry and in the medical field. They are responsible for huge economical losses in many industrial sectors and for serious infections associated with biomaterial implants and medical devices. These infections are hard to treat because bacteria within the biofilm are more resistant to antibiotics and to the host immune system. Therefore, studying biofilm properties and mechanisms is of utmost relevance to develop efficient approaches to deal with this drawback. Biofilm thickness is an important parameter in biofilm characterization. The main purpose of this thesis was to assess the suitability of Optical Coherence Tomography ...

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    15. Non-destructive morphological observation of anatomical growth process in Haemaphysalis Longicornis tick specimens using optical coherence tomography

      Non-destructive morphological observation of anatomical growth process in Haemaphysalis Longicornis tick specimens using optical coherence tomography

      Background: Ticks are known as the representatives of hematophagous arachnids. They cause various tick-borne diseases, such as severe fever with thrombocytopenia syndrome (SFTS) and Lyme disease. To understand the mechanism of virus infection caused by ticks, morphology for the anatomical characteristics of crucial organs has been widely studied in acarological fields. The conventional methods used for tick observation have inevitable limitations. Dissection is the standard method to obtain the morphological information, and complex microscopy methods were utilized alternatively. Objective: The study goal is to obtain the morphological information of ticks in different growth stages non-invasively. Methods: Optical coherence tomography (OCT ...

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    16. Biophysical properties at patch scale shape the metabolism of biofilm landscapes

      Biophysical properties at patch scale shape the metabolism of biofilm landscapes

      Phototrophic biofilms form complex spatial patterns in streams and rivers, yet, how community patchiness, structure and function are coupled and contribute to larger-scale metabolism remains unkown. Here, we combined optical coherence tomography with automated O 2 microprofiling and amplicon sequencing in a flume experiment to show how distinct community patches interact with the hydraulic environment and how this affects the internal distribution of oxygen. We used numerical simulations to derive rates of community photosynthetic activity and respiration at the patch scale and use the obtained parameter to upscale from individual patches to the larger biofilm landscape. Our biofilm landscape approach ...

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    17. How Do You Drill a Million Holes?

      How Do You Drill a Million Holes?

      Drilling was performed “on-the-fly,” i.e. with a constant feed rate of the optical system relative to the workpiece. Using the optimized process parameters, the institute was able to machine a 2 meter long 3D-molded demonstrator of an aircraft wing on a 6-axis system. At a speed of 200 holes per second, about 2 million holes per square meter were drilled on an area of about 2 m² in less than three hours. The diameter of the holes was 80 µm. It was also important to precisely control the distance between the optical systems and the workpiece. Optical coherence tomography ...

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    18. Biospeckle Optical Coherence Tomography (bOCT) in the Speedy Assessment of the Responses of the Seeds of Raphanus sativus L. (Kaiware Daikon) to Acid Mine Drainage (AMD)

      Biospeckle Optical Coherence Tomography (bOCT) in the Speedy Assessment of the Responses of the Seeds of Raphanus sativus L. (Kaiware Daikon) to Acid Mine Drainage (AMD)

      The extraction of mineral resources from mines plays a vital role in global socio-economic development. However, acid mine drainage (AMD) has been one of the major pollutants, and a vast area of the agricultural fields has been polluted. Therefore, techniques for monitoring the response of plants to AMD that arise during mineral extraction are necessary. In addition, such a technique becomes especially valuable to understand how the plants could play a role in the phytoremediation of AMD. We propose the use of biospeckle Optical Coherence Tomography (bOCT) to investigate the response of Kaiware daikon seeds under the exposure to simulated ...

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    19. Characterization of Biofilm Structure and Properties via Processing of 2D Optical Coherence Tomography Images in BISCAP

      Characterization of Biofilm Structure and Properties via Processing of 2D Optical Coherence Tomography Images in BISCAP

      Motivation: Processing of Optical Coherence Tomography (OCT) biofilm images is currently restricted to a set of custom-made MATLAB scripts. None of the tools currently available for biofilm image processing (including those developed for Confocal Laser Scanning Microscopy-CLSM) enable a fully automatic processing of 2D OCT images. Results: A novel software tool entitled BISCAP (Biofilm Imaging and Structure Classification Automatic Processor) is presented. It was developed specifically for the automatic processing of 2D OCT biofilm images. The proposed approach makes use of some of the key principles used in CLSM image processing, and introduces a novel thresholding algorithm and substratum detection ...

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    20. Unraveling the Kinetics and Mechanism of Surfactant-Induced Wetting in Membrane Distillation: An In Situ Observation with Optical Coherence Tomography

      Unraveling the Kinetics and Mechanism of Surfactant-Induced Wetting in Membrane Distillation: An In Situ Observation with Optical Coherence Tomography

      In this study, we performed a direct contact membrane distillation and successfully demonstrated the non-invasive imaging of surfactant-induced wetting using optical coherence tomography. This method enabled us to investigate the wetting kinetics, which was found to follow a "three-region" relationship between the wetting rate and surfactant concentration: the (i) nonwetted region, (ii) concentration-dependent region, and (iii) concentration-independent region at low, intermediate, and high surfactant concentrations, respectively. This wetting behavior was explained by the "autophilic effect", i.e., the wetting was caused by the transfer of surfactants from the water-vapor interface to the unwetted membrane and rendered this membrane hydrophilic, and ...

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    21. Real-Time Monitoring and Quantitative Evaluation of Resin In-Filtrant Repairing Enamel White Spot Lesions Based on Optical Coherence Tomography

      Real-Time Monitoring and Quantitative Evaluation of Resin In-Filtrant Repairing Enamel White Spot Lesions Based on Optical Coherence Tomography

      The aim of the present study was to explore the feasibility of real-time monitoring and quantitative guiding the repair of enamel white spot lesions (WSLs) with resin infiltration by optical coherence tomography (OCT). Seven New Zealand rabbits were treated with 37% phosphoric acid etchant for 15 min to establish the model of enamel demineralization chalk spots of upper incisors, which were repaired by Icon resin infiltrant. OCT, stereo microscope (SM) imaging, scanning electron microscope (SEM) imaging and hematoxylin eosin (HE) staining were used to image each operation step. The changes of WSLs of enamel before and in the process of ...

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    22. Metrological performance analysis of optical coherent tomography

      Metrological performance analysis of optical coherent tomography

      A spectral-domain optical coherence tomography (SD-OCT) system with 1555nm center wavelength is tested for stability and accuracy from the micron level to the sub-micron level. The energy centrobaric correction method is used to extract the sub-axial-resolution information as the optical path difference, i.e., the topographic height. We compared the used algorithm with the widely applied phase slope method. The stability of a point scanning OCT system in Michelson style is experimentally compared with that of a system in Fizeau style. Several simple and complicated samples are measured and compared. Finally, we compare the topographic performance of the OCT system ...

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    23. Use of optical coherence tomography (OCT) as a metrological tool measuring the volume of HepG2 tumor cell spheroids

      Use of optical coherence tomography (OCT) as a  metrological tool measuring the volume of HepG2 tumor  cell spheroids

      The advent of the use of cellular spheroids in biomedical research witnessed in recent years has continuously demonstrated the advantageous potential of their use in laboratory experiments . Added to such advances, the necessity to apply reliable methods of quality control of this type of cell culture grows simultaneously within this progress. In a scenario where centuries - old techniques to control quantitative parameters such as diameter and volume are still used, with emphasis on microscopy modalities, capable of providing images from unidirectinonal projections, optical coherence tomography (O C T) has been considered as an alternative so such methodologies. Indeed, in recent ...

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    24. Measurement of refractive index spectrum of optical material by phase detection with optical coherence tomography

      Measurement of refractive index spectrum of optical material by phase detection with optical coherence tomography

      Refractive index (RI) is a fundamental parameter of optical material, and RI spectrum (RIS) is essential for many fields. Current RI measurement is only for some discrete spectral lines, and has extremely high requirements on measurement operation and accuracy. A measurement method of continuous RIS distribution in a wide spectral range was proposed in this work. A swept-source optical coherence tomography using a Mach-Zehnder configuration was used to detect interference spectrum signal, which phase was obtained by using Hilbert transform. By detecting the sample-induced phase and using the proposed equations, RIS of a sample could be obtained. Five measurements on ...

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