Handheld probes and galvanometer scanning for optical coherence tomography

Duma, Virgil-Florin; Dobre, George; Demian, Dorin; Cernat, Ramona; Sinescu, Cosmin; Topală, Florin; Negruțiu, Meda Lavinia; Hutiu, Gh.; Bradu, Adrian; Rolland, Jannick P.; Podoleanu, Adrian Gh.

doi:10.1117/12.2191130

Cited by 23 publications

(32 citation statements)

References 32 publications

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“…The former aspect has not been exploited in the present study; it is subject of future work to perform in situ investigations, of different damaged parts, made of different materials (including light alloys), using an OCT mobile unit and handheld scanning probes that we have been developing [21,22]-including for forensic assessments.…”

Section: Discussionmentioning

confidence: 99%

Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

Huţiu

Duma

Demian

et al. 2018

Metals

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Some forensic in situ investigations, such as those needed in transportation (for aviation, maritime, road, or rail accidents) or for parts working under harsh conditions (e.g., pipes or turbines) would benefit from a method/technique that distinguishes ductile from brittle fractures of metals-as material defects are one of the potential causes of incidents. Nowadays, the gold standard in material studies is represented by scanning electron microscopy (SEM). However, SEM instruments are large, expensive, time-consuming, and lab-based; hence, in situ measurements are impossible. To tackle these issues, we propose as an alternative, lower-cost, sufficiently high-resolution technique, Optical Coherence Tomography (OCT) to perform fracture analysis by obtaining the topography of metallic surfaces. Several metals have been considered in this study: low soft carbon steels, lamellar graphite cast iron, an antifriction alloy, high-quality rolled steel, stainless steel, and ductile cast iron. An in-house developed Swept Source (SS) OCT system, Master-Slave (MS) enhanced is used, and height profiles of the samples' surfaces were generated. Two configurations were used: one where the dimension of the voxel was 1000 µm 3 and a second one of 160 µm 3 -with a 10 µm and a 4 µm transversal resolution, respectively. These height profiles allowed for concluding that the carbon steel samples were subject to ductile fracture, while the cast iron and antifriction alloy samples were subjected to brittle fracture. The validation of OCT images has been made with SEM images obtained with a 4 nm resolution. Although the OCT images are of a much lower resolution than the SEM ones, we demonstrate that they are sufficiently good to obtain clear images of the grains of the metallic materials and thus to distinguish between ductile and brittle fractures-especially with the higher resolution MS/SS-OCT system. The investigation is finally extended to the most useful case of fatigue fracture of metals, and we demonstrate that OCT is able to replace SEM for such investigations as well.

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Section: Discussionmentioning

confidence: 99%

Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

Huţiu

Duma

Demian

et al. 2018

Metals

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“…The advantages, as well as the limitations/complementarities of OCT in relationship to other investigation methods have been reported in respect to imaging teeth [25][26][27] or different types of dental constructs [28][29][30][31][32][33]. Relevant to non-destructive testing, targeted here, the impact of the OCT light source, of its central wavelength, as well as of specular reflection, have already been considered [23].…”

Section: Introductionmentioning

confidence: 99%

Effects of Temperature Variations during Sintering of Metal Ceramic Tooth Prostheses Investigated Non-Destructively with Optical Coherence Tomography

et al. 2017

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Calibration loss of ovens used in sintering metal ceramic prostheses leads to stress and cracks in the material of the prostheses fabricated, and ultimately to failure of the dental treatment. Periodic calibration may not be sufficient to prevent such consequences. Evaluation methods based on firing supplemental control samples are subjective, time-consuming, and rely entirely on the technician's skills. The aim of this study was to propose an alternative procedure for such evaluations. Fifty prostheses were sintered in a ceramic oven at a temperature lower, equal to or larger than the temperature prescribed by the manufacturer. A non-destructive imaging method, swept source (SS) optical coherence tomography (OCT) was used to evaluate comparatively the internal structure of prostheses so fabricated. A quantitative assessment procedure is proposed, based on en-face OCT images acquired at similar depths inside the samples. Differences in granulation and reflectivity depending on the oven temperature are used to establish rules-of-thumb on judging the correct calibration of the oven. OCT evaluations made on a regular basis allow an easy and objective monitoring of correct settings in the sintering process. This method can serve rapid identification of the need to recalibrate the oven and avoid producing prostheses with defects.

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“…The present study demonstrates that OCT can replace the SEM in the analysis of metallic surfaces broken in both a ductile and a brittle manner. 3) Another advantage of the OCT method as compared to the SEM is that the former can generate the image of the entire sample surface through consecutive scanning operations using an OCT mobile unit and handheld scanning probes [15,16]. These scanning operations do not destroy the metallic parts, which is an essential issue in the case of aviation, maritime, road or rail accidents, etc.…”

Section: Discussionmentioning

confidence: 99%

“…A steel sample subjected to ductile fracture is considered as an example in the present paper. The tests carried out have been demonstrated that the OCT method is capable to replace the gold standard in this field, i.e., the SEM method, that has much higher resolutions, but also higher cost, and it is labor and time consuming; it is also strictly lab-based, in comparison with OCT, which can work as mobile units equipped with handheld scanning probes with galvoscanners [15,16] or Micro-Electro-Mechanical Systems (MEMS) [18], in order to perform in situ, industrial or forensic investigations.…”

Section: Introductionmentioning

confidence: 99%

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Analysis of the fractures of metallic materials using optical coherence tomography

et al. 2017

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Forensic in situ investigations, for example for aviation, maritime, road, or rail accidents would benefit from a method that may allow to distinguish ductile from brittle fractures of metals -as material defects are one of the potential causes of such accidents. Currently, the gold standard in material studies is represented by scanning electron microscopy (SEM). However, SEM are large, lab-based systems, therefore in situ measurements are excluded. In addition, they are expensive and time-consuming. We have approached this problem and propose the use of Optical Coherence Tomography (OCT) in such investigations in order to overcome these disadvantages of SEM. In this respect, we demonstrate the capability to perform such fracture analysis by obtaining the topography of metallic surfaces using OCT. Different materials have been analyzed; in this presentation a sample of low soft carbon steel with the chemical composition of C 0.2%, Mn 1.15%, S 0.04%, P 0.05 % and Fe for the rest has been considered. An in-house developed Swept Source (SS) OCT system has been used, and height profiles have been generated for the sample surface. This profile allowed for concluding that the carbon steel sample was subjected to a ductile fracture. A validation of the OCT images obtained with a 10 microns resolution has been made with SEM images obtained with a 4 nm resolution. Although the OCT resolution is much lower than the one of SEM, we thus demonstrate that it is sufficient in order to obtain clear images of the grains of the metallic materials and thus to distinguish between ductile and brittle fractures. This study analysis opens avenues for a range of applications, including: (i) to determine the causes that have generated pipe ruptures, or structural failures of metallic bridges and buildings, as well as damages of machinery parts; (ii) to optimize the design of various machinery; (iii) to obtain data regarding the structure of metallic alloys); (iv) to improve the manufacturing technologies of metallic parts.

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Handheld probes and galvanometer scanning for optical coherence tomography

Cited by 23 publications

References 32 publications

Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

Effects of Temperature Variations during Sintering of Metal Ceramic Tooth Prostheses Investigated Non-Destructively with Optical Coherence Tomography

Analysis of the fractures of metallic materials using optical coherence tomography

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