1. Articles from Samuel Lawman

    1-10 of 10
    1. Sub-surface imaging of soiled cotton fabric using full-field optical coherence tomography

      Sub-surface imaging of soiled cotton fabric using full-field optical coherence tomography

      In the laundry industry, colorimetry is a common way to evaluate the stain removal efficiency of detergents and cleaning products. For ease of visualization, the soiling agent is treated with a dye before measurement. However, it effectively measures the dye removal rather than stain removal, and it cannot provide depth-resolved information of the sample. In this study, we show that full-field (FF) optical coherence tomography (OCT) technique is capable of measuring the cleaning effect on cotton fabric by imaging the sub-surface features of fabric samples. We used a broadband light-emitting diode (LED) source to power the FF-OCT system that achieves ...

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      Mentions: Yalin Zheng
    2. Line-Field Optical Coherence Tomography as a tool for In vitro characterization of corneal biomechanics under physiological pressures

      Line-Field Optical Coherence Tomography as a tool for In vitro characterization of corneal biomechanics under physiological pressures

      There has been a lot of interest in accurately characterising corneal biomechanical properties under intraocular pressure (IOP) to help better understand ocular pathologies that are associated with elevated IOP. This study investigates the novel use of Line-Field Optical Coherence Tomography (LF-OCT) as an elastographic tool for accurately measuring mechanical properties of porcine corneas based on volumetric deformation following varying IOPs. A custom-built LF-OCT was used to measure geometrical and corneal surface displacement changes in porcine corneas under a range of IOPs, from 0–60 mmHg. Corneal thickness, elastic properties and hysteresis were calculated as a function of pressure. In addition ...

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      Mentions: Yalin Zheng
    3. Imaging of Corneal Neovascularization: Optical Coherence Tomography Angiography and Fluorescence Angiography

      Imaging of Corneal Neovascularization: Optical Coherence Tomography Angiography and Fluorescence Angiography

      Purpose : The purpose of this study was to compare optical coherence tomography angiography (OCTA) and indocyanine green angiography (ICGA) for the assessment of corneal neovascularization (CoNV). Methods : Patients with CoNV extending at least 3 mm into the cornea were included. All patients underwent corneal imaging at the same visit. Images were recorded using the AngioVue OCTA system (Optovue, Inc.) with the long corneal adaptor module (CAM-L). ICGA images were recorded with fluorescent filters using the Heidelberg system (HRA2 Scanning Laser Ophthalmoscope; Heidelberg Engineering). Images were graded for quality by two independent observers. Vessel parameters: area, number, diameter, branch and end ...

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    4. Deformation velocity imaging using optical coherence tomography and its applications to the cornea

      Deformation velocity imaging using optical coherence tomography and its applications to the cornea

      Optical coherence tomography (OCT) can monitor human donor corneas non-invasively during the de-swelling process following storage for corneal transplantation, but currently only resultant thickness as a function of time is extracted. To visualize and quantify the mechanism of de-swelling, we present a method exploiting the nanometer sensitivity of the Fourier phase in OCT data to image deformation velocities. The technique was demonstrated by non-invasively showing during de-swelling that osmotic flow through an intact epithelium is negligible and removing the endothelium approximately doubled the initial flow at that interface. The increased functional data further enabled the validation of a mathematical model ...

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      Mentions: Yalin Zheng
    5. Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation

      Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation

      Automotive coating systems are designed to protect vehicle bodies from corrosion and enhance their aesthetic value. The number, size and orientation of small metallic flakes in the base coat of the paint has a significant effect on the appearance of automotive bodies. It is important for quality assurance (QA) to be able to measure the properties of these small flakes, which are approximately 10 μm in radius, yet current QA techniques are limited to measuring layer thickness. We design and develop a time-domain (TD) full-field (FF) optical coherence tomography (OCT) system to scan automotive panels volumetrically, non-destructively and without contact ...

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    6. Scan-Less Line Field Optical Coherence Tomography, with Automatic Image Segmentation, as a Measurement Tool for Automotive Coatings

      Scan-Less Line Field Optical Coherence Tomography, with Automatic Image Segmentation, as a Measurement Tool for Automotive Coatings

      The measurement of the thicknesses of layers is important for the quality assurance of industrial coating systems. Current measurement techniques only provide a limited amount of information. Here, we show that spectral domain Line Field (LF) Optical Coherence Tomography (OCT) is able to return to the user a cross sectional B-Scan image in a single shot with no mechanical moving parts. To reliably extract layer thicknesses from such images of automotive paint systems, we present an automatic graph search image segmentation algorithm. To show that the algorithm works independently of the OCT device, the measurements are repeated with a separate ...

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      Mentions: Yalin Zheng
    7. High resolution corneal and single pulse imaging with line field spectral domain optical coherence tomography

      High resolution corneal and single pulse imaging with line field spectral domain optical coherence tomography

      We report the development of a Spectral Domain Line Field Optical Coherence Tomography (LF-OCT) system, using a broad bandwidth and spatial coherent Super-Continuum (SC) source. With conventional quasi-Continuous Wave (CW) setup we achieve axial resolutions up to 2.1 μm in air and 3D volume imaging speeds up to 213 kA-Scan/s. Furthermore, we report the use of a single SC pulse, of 2 ns duration, to temporally gate an OCT B-Scan image of 70 A-Scans. This is the equivalent of 35 GA-Scans/s. We apply the CW setup for high resolution imaging of the fine structures of a human ...

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      Mentions: Yalin Zheng
    8. Nondestructive analysis of automotive paints with spectral domain optical coherence tomography

      Nondestructive analysis of automotive paints with spectral domain optical coherence tomography

      We have demonstrated for the first time, to our knowledge, the use of optical coherence tomography (OCT) as an analytical tool for nondestructively characterizing the individual paint layer thickness of multiple layered automotive paints. A graph-based segmentation method was used for automatic analysis of the thickness distribution for the top layers of solid color paints. The thicknesses measured with OCT were in good agreement with the optical microscope and ultrasonic techniques that are the current standard in the automobile industry. Because of its high axial resolution (5.5 μm), the OCT technique was shown to be able to resolve the ...

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      Mentions: Yalin Zheng
    9. High precision dynamic multi-interface profilometry with optical coherence tomography

      High precision dynamic multi-interface profilometry with optical coherence tomography
      Optical coherence tomography (OCT) has mostly been used for high-speed volume imaging but its profilometry potentials have not been fully exploited. This paper demonstrates high precision (as good as ∼50 nm) multi-interface profilometry using a Fourier domain OCT system without special antivibration devices. The precision is up to 2 orders of magnitude better than the depth resolution of the OCT. Detailed analysis of the precision achieved for different surfaces is presented. The multi-interface profiles are obtained as a by-product of the tomography data. OCT has the advantage in speed and sensitivity at detecting rough and internal interfaces versus conventional optical ...
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    10. Fourier domain optical coherence tomography for high-precision profilometry

      A Fourier domain (FD) optical coherence tomography (OCT) system is shown to be capable of profilometry with two orders of magnitude better accuracy than the axial imaging resolution of the system. High precision OCT profilometry not only achieves similar accuracy as commercial white light interferometry based profilometers but is also capable of profilometry on complex subsurface structures with multiple interfaces of low reflectance. An accuracy of 55nm was achieved with a ThorLabs SROCT on a lab bench without special anti-vibration devices. This technique has the potential for a range of applications, such as high precision refractive index measurements and simultaneous ...
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    1-10 of 10
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  2. Topics in the News

    1. (7 articles) Yalin Zheng
    2. (2 articles) Nottingham Trent University
    3. (2 articles) Haida Liang
    4. (1 articles) Optovue
    5. (1 articles) Thorlabs
    6. (1 articles) Heidelberg Engineering
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    High precision dynamic multi-interface profilometry with optical coherence tomography Nondestructive analysis of automotive paints with spectral domain optical coherence tomography High resolution corneal and single pulse imaging with line field spectral domain optical coherence tomography Scan-Less Line Field Optical Coherence Tomography, with Automatic Image Segmentation, as a Measurement Tool for Automotive Coatings Non-destructive analysis of flake properties in automotive paints with full-field optical coherence tomography and 3D segmentation Deformation velocity imaging using optical coherence tomography and its applications to the cornea Imaging of Corneal Neovascularization: Optical Coherence Tomography Angiography and Fluorescence Angiography Line-Field Optical Coherence Tomography as a tool for In vitro characterization of corneal biomechanics under physiological pressures Sub-surface imaging of soiled cotton fabric using full-field optical coherence tomography Postdoctoral Associate Position at Duke Vision and Image Processing Laborator Anterior segment optical coherence tomography angiography Refining percutaneous coronary intervention: intracoronary imaging, haemodynamics, P2Y12 antagonists, and public outcomes reporting