scholarly journals Spectroscopic Optical Coherence Tomography for Thin Layer and Foil Measurements

Sensors ◽  
2020 ◽  
Vol 20 (19) ◽  
pp. 5653
Author(s):  
Aleksandra M. Kamińska ◽  
Marcin R. Strąkowski ◽  
Jerzy Pluciński
Keyword(s):  
Optical Coherence Tomography ◽  
Thin Layer ◽  
Michelson Interferometer ◽  
High Sensitivity ◽  
Thin Foil ◽  
Thin Layers ◽  
Optical Coherence ◽  
Minimum Value ◽  
Proposed Model ◽  
Fabry Perot

The main goal of this research was to assess if it is possible to evaluate the thickness of thin layers (both thin films on the surface and thin layers below the surface of the tested object) and foils using optical coherence tomography (OCT) for thickness assessment under the resolution of the standard commercially available OCT measurement system. In the proposed solution, light backscattered from the evaluated thin layer has been expressed as a multiple beam interference. Therefore, the OCT system was modeled as a two-beam interferometer (e.g., Michelson), in which one beam propagates from the reference arm and the other comes from a Fabry–Pérot interferometer. As a consequence, the mathematical model consists of the main Michelson interferometer, in which the measuring arm represents the Fabry–Pérot interferometer. The parameters of the layer (or foil) are evaluated by analyzing the minimum value of the interference contrast. The model developed predicts the behavior of the thin layers made from different materials (with different refractive indexes) with different thickness and located at different depths. To verify the correctness of the proposed model, an experiment with a wedge cell has been carried out. The wedge cell was shifted across the scanning beam using a linear translation stage with a micrometer screw under the scanning head. The relationship between the thickness of the gap of the wedge cell and the OCT output signal is presented. For the additional verification of the proposed model, the results of the measurements of the thickness of the thin foil were compared with the theoretical results of the simulations. The film thickness was evaluated based on the calculated positions of the minimum value of interference contrast. A combination of the standard potentialities of OCT with the proposed approach to analyzing the signal produces new metrological possibilities. The method developed allows us to evaluate thickness under the resolution of the system and the location of the layer as well. This produces the possibility of measuring a layer which is covered by another layer. Moreover, it is possible to create a thickness map with high sensitivity to thickness changes. These experiments and simulations are the culmination of preliminary research for evaluating the potential of the proposed measurement method.

scholarly journals All-optically integrated photoacoustic and optical coherence tomography: A review

2017 ◽  
Vol 10 (04) ◽  
pp. 1730006 ◽  
Author(s):  
Wei Qiao ◽  
Zhongjiang Chen
Keyword(s):  
Optical Coherence Tomography ◽  
Biomedical Imaging ◽  
Imaging System ◽  
Michelson Interferometer ◽  
Optical Coherence ◽  
Dual Mode ◽  
Imaging Technology ◽  
Fabry Perot ◽  
All Optical ◽  
Potential Applications

All-optically integrated photoacoustic (PA) and optical coherence tomography (OCT) dual-mode imaging technology that could offer comprehensive pathological information for accurate diagnosis in clinic has gradually become a promising imaging technology in the aspect of biomedical imaging during the recent years. This review refers to the technology aspects of all-optical PA detection and system evolution of optically integrated PA and OCT, including Michelson interferometer dual-mode imaging system, Fabry–Perot (FP) interferometer dual-mode imaging system and Mach–Zehnder interferometer dual-mode imaging system. It is believed that the optically integrated PA and OCT has great potential applications in biomedical imaging.

Ex Vivo assessment of competent strut coverage after coronary stenting by optical coherence tomography

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
R Bhoite ◽  
H Jinnouchi ◽  
F Otsuka ◽  
Y Sato ◽  
A Sakamoto ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Predictive Value ◽  
Ex Vivo ◽  
High Sensitivity ◽  
Optical Coherence ◽  
Cross Sectional ◽  
Neointimal Thickness ◽  
Stent Strut ◽  
Oct Imaging ◽  
Definition Of

Abstract Background In many studies, struts coverage is defined as >0 mm of tissue overlying the stent struts by optical coherence tomography (OCT). However, this definition has never been validated using histology as the “gold standard”. The present study sought to assess the appropriate cut-off value of neointimal thickness of stent strut coverage by OCT using histology. Methods OCT imaging was performed on 39 human coronary arteries with stents from 25 patients at autopsy. A total of 165 cross-sectional images from 46 stents were co-registered with histology. The optimal cut-off value of strut coverage by OCT was determined. Strut coverage by histology was defined as endothelial cells with at least underlying two layers of smooth muscle cells. Considering the resolution of OCT is 10–20 μm, 3 different cut-off values (i.e. at ≥20, ≥40, and ≥60 μm) were assessed. Results A total of 2235 struts were evaluated by histology. Eventually, 1216 struts which were well-matched struts were analyzed in this study. By histology, uncovered struts were observed in 160 struts and covered struts were observed in 1056 struts. The broadly used definition of OCT-coverage which does not consider neointimal thickness yielded a poor specificity of 37.5% and high sensitivity 100%. Of 3 cut-off values, the cut-off value of >40 μm was more accurate as compared to >20 and >60 mm [sensitivity (99.3%), specificity (91.0%), positive predictive value (98.6%), and negative predictive value (95.6%)] Conclusion The most accurate cut-off value was ≥40 μm neointimal thickness by OCT in order to identify stent strut coverage validated by histology. Funding Acknowledgement Type of funding source: None

High sensitivity measurements of the scattering dispersion of phantoms using spectral domain optical coherence tomography

2006 ◽  
Author(s):  
Shellee D. Dyer ◽  
Tasshi Dennis ◽  
Paul A. Williams ◽  
Lara K. Street ◽  
Shelley M. Etzel ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
High Sensitivity ◽  
Spectral Domain ◽  
Optical Coherence

High-sensitivity determination of birefringence in turbid media with enhanced polarization-sensitive optical coherence tomography

2005 ◽  
Vol 22 (3) ◽  
pp. 552 ◽  
Author(s):  
Nate J. Kemp ◽  
Jesung Park ◽  
Haitham N. Zaatari ◽  
H. Grady Rylander ◽  
Thomas E. Milner
Keyword(s):  
Optical Coherence Tomography ◽  
High Sensitivity ◽  
Turbid Media ◽  
Optical Coherence

scholarly journals Investigation of Light Parameters on Image Quality and Optical Coherence Tomography

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Boka Fikadu ◽  
Bulcha Bekele ◽  
Leta Tesfaye Jule ◽  
Anatol Degefa ◽  
N. Nagaprasad ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Image Quality ◽  
Time Domain ◽  
Glass Sample ◽  
Michelson Interferometer ◽  
Signal Strength ◽  
Optical Coherence ◽  
Time Domain Signal ◽  
Significant Difference ◽  
The Time Domain

In this work, image quality and optical coherence tomography were studied. The results of the study show that there is a very significant difference between ultrasound and optical coherence tomography to produce an image with a different wave. To understand this, we studied the basic principle of optical coherence tomography in the Michelson interferometer using monochromatic and broadband sources. Time-domain and spectral-domain measurements, which exist at the detector level, are briefly described using a glass sample. The time-domain signal strength of the Michelson interferometer using a broadband source is a Gaussian envelope.

scholarly journals Flexible Computationally Efficient Platform for Simulating Scan Formation in Optical Coherence Tomography with Accounting for Arbitrary Motions of Scatterers

2021 ◽  
Vol 7 (1) ◽  
pp. 010304
Author(s):  
Alexey Zykov ◽  
Alexander Matveyev ◽  
Lev Matveev ◽  
Alexander Sovetsky ◽  
Vladimir Zaitsev
Keyword(s):  
Optical Coherence Tomography ◽  
Numerical Simulations ◽  
Biological Tissues ◽  
Realistic Model ◽  
Spectral Domain ◽  
Optical Coherence ◽  
Computationally Efficient ◽  
Proposed Model ◽  
Speckle Patterns ◽  
Rotational Motions

A computationally efficient and fairly realistic model of OCT-scan formation in spectral-domain optical coherence tomography is described. The model is based on the approximation of discrete scatterers and ballistic character of scattering, these approximations being widely used in literature. An important feature of the model is its ability to easily account for arbitrary scatterer motions and computationally efficiently generate large sequences of OCT scans for gradually varying configurations of scatterers. This makes the proposed simulation platform very convenient for studies related to the development of angiographic processing of OCT scans for visualization of microcirculation of blood, as well as for studies of decorrelation of speckle patterns in OCT scans due to random (Brownian type) motions of scatterers. Examples demonstrating utilization of the proposed model for generation OCT scans imitating perfused vessels in biological tissues, as well as evolution of speckles in OCT scans due to random translational and rotational motions of localized (but not-point-like) scatterers are given. To the best of our knowledge, such numerical simulations of large series of OCT scans in the presence of various types of motion of scatterers have not been demonstrated before.

Extended measuring depth dual-wavelength Fourier domain optical coherence tomography

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Haroun Al-Mohamedi ◽  
Ismael Kelly-Pérez ◽  
Theo Oltrup ◽  
Alan Cayless ◽  
Thomas Bende
Keyword(s):  
Optical Coherence Tomography ◽  
Wide Spectrum ◽  
Michelson Interferometer ◽  
Dual Band ◽  
Human Model ◽  
Optical Coherence ◽  
Reference Mirror ◽  
Pass Filter ◽  
Wide Range ◽  
Sd Oct

Abstract In this work an enhanced wide range dual band spectral domain optical coherence tomography technique (SD-OCT) is presented to increase the depth and accuracy of the measurement of optical A-scan biometry. The setup uses a Michelson interferometer with two wide-spectrum Superluminescent Diodes (SLD). The emissions of the SLDs are filtered by a long-pass filter (900 nm) in front of the reference mirror. The light is spectrally decomposed using a single reflective diffraction grating (1,800 lines/mm) and the whole spectrum captured with two CCD line sensors. The capabilities of the system have been validated using a self-made human model eye.

scholarly journals Multimodal instrument for high-sensitivity autofluorescence and spectral optical coherence tomography of the human eye fundus

2013 ◽  
Vol 4 (11) ◽  
pp. 2683 ◽  
Author(s):  
Katarzyna Komar ◽  
Patrycjusz Stremplewski ◽  
Marta Motoczyńska ◽  
Maciej Szkulmowski ◽  
Maciej Wojtkowski
Keyword(s):  
Optical Coherence Tomography ◽  
High Sensitivity ◽  
Optical Coherence ◽  
Human Eye ◽  
Spectral Optical Coherence Tomography

scholarly journals High sensitivity phase mapping with parallel Fourier domain optical coherence tomography at 512 000 A-scan/s

2010 ◽  
Vol 18 (21) ◽  
pp. 21841 ◽  
Author(s):  
Branislav Grajciar ◽  
Yves Lehareinger ◽  
Adolf F. Fercher ◽  
Rainer A. Leitgeb
Keyword(s):  
Optical Coherence Tomography ◽  
High Sensitivity ◽  
Fourier Domain ◽  
Optical Coherence ◽  
Phase Mapping
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