1. Articles from Ling Wang

    1-16 of 16
    1. Distribution of scleral thickness and associated factors in 810 Chinese children and adolescents: a swept‐source optical coherence tomography study

      Distribution of scleral thickness and associated factors in 810 Chinese children and adolescents: a swept‐source optical coherence tomography study

      Purpose To explore the subfoveal thickness of sclera (SST), choroid (SCT) and retina (SRT) as well as their relationship in healthy Chinese children with varying levels of refractive error. Methods A total of 810 healthy Chinese schoolchildren and adolescents underwent a series of comprehensive ocular examinations, as well as swept‐source optical coherence tomography (OCT) after induced cycloplegia. The thicknesses of the sclera, choroid and retina below the central fovea were measured manually, and each measurement was compared across different refractive statuses. Independent factors associated with the thickness of each layer were analysed. Results The mean SST, SCT and SRT ...

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    2. Quantitative angle-insensitive flow measurement using relative standard deviation OCT

      Quantitative angle-insensitive flow measurement using relative standard deviation OCT

      Incorporating different data processing methods, optical coherence tomography (OCT) has the ability for high-resolution angiography and quantitative flow velocity measurements. However, OCT angiography cannot provide quantitative information of flow velocities, and the velocity measurement based on Doppler OCT requires the determination of Doppler angles, which is a challenge in a complex vascular network. In this study, we report on a relative standard deviation OCT (RSD-OCT) method which provides both vascular network mapping and quantitative information for flow velocities within a wide range of Doppler angles. The RSD values are angle-insensitive within a wide range of angles, and a nearly linear ...

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    3. Automated quantitative assessment of three-dimensional bioprinted hydrogel scaffolds using optical coherence tomography

      Automated quantitative assessment of three-dimensional bioprinted hydrogel scaffolds using optical coherence tomography

      Reconstructing and quantitatively assessing the internal architecture of opaque three-dimensional (3D) bioprinted hydrogel scaffolds is difficult but vital to the improvement of 3D bioprinting techniques and to the fabrication of functional engineered tissues. In this study, swept-source optical coherence tomography was applied to acquire high-resolution images of hydrogel scaffolds. Novel 3D gelatin/alginate hydrogel scaffolds with six different representative architectures were fabricated using our 3D bioprinting system. Both the scaffold material networks and the interconnected flow channel networks were reconstructed through volume rendering and binarisation processing to provide a 3D volumetric view. An image analysis algorithm was developed based on ...

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    4. Fiber-optically integrated cost-effective spectrometer for optical coherence tomography

      Fiber-optically integrated cost-effective spectrometer for optical coherence tomography

      A tilted fiber Bragg grating (TFBG) was integrated as the dispersive element in a high performance biomedical imaging system. The spectrum emitted by the 23 mm long active region of the fiber is projected through custom designed optics consisting of a cylindrical lens for vertical beam collimation and successively by an achromatic doublet onto a linear detector array. High resolution tomograms of biomedical samples were successfully acquired by the frequency domain OCT-system. Tomograms of ophthalmic and dermal samples obtained by the frequency domain OCT-system were obtained achieving 2.84 μm axial and 10.2 μm lateral resolution. The miniaturization reduces ...

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    5. Cost-effective optical coherence tomography spectrometer based on a tilted fiber Bragg grating

      Cost-effective optical coherence tomography spectrometer based on a tilted fiber Bragg grating

      A compact, fiber-based spectrometer for biomedical application utilizing a tilted fiber Bragg grating (TFBG) as integrated dispersive element is demonstrated. Based on a 45° UV-written PS750 TFBG a refractive spectrometer with 2.06 radiant/μm dispersion and a numerical aperture of 0.1 was set up and tested as integrated detector for an optical coherence tomography (OCT) system. Featuring a 23 mm long active region at the fiber the spectrum is projected via a cylindrical lens for vertical beam collimation and focused by an achromatic doublet onto the detector array. Covering 740 nm to 860 nm the spectrometer was optically ...

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    6. High-sensitive quantitative phase imaging with averaged spectral domain phase microscopy

      High-sensitive quantitative phase imaging with averaged spectral domain phase microscopy

      We present an averaged spectral domain phase microscopy (A-SDPM) for high-sensitive quantitative phase imaging, where multiple spectral phases from different wavenumbers are fully exploited to determine the final optical path difference (OPD). Uncertainties of recovered spectral phases and OPDs at all wavenumbers are investigated, and a threshold value for the uncertainty of OPD is set to obtain the optimized averaging. A sensitivity of 17.84 pm is achieved under signal to noise ratio (SNR) of 61 dB, resulting in a 4.11 fold reduction in noise compared with the single spectral phase approach. The performance of the proposed A-SDPM is ...

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    7. Graphics processing unit-based dispersion encoded full-range frequency-domain optical coherence tomography

      Graphics processing unit-based dispersion encoded full-range frequency-domain optical coherence tomography

      Dispersion encoded full-range (DEFR) frequency-domain optical coherence tomography (FD-OCT) and its enhanced version, fast DEFR, utilize dispersion mismatch between sample and reference arm to eliminate the ambiguity in OCT signals caused by non-complex valued spectral measurement, thereby numerically doubling the usable information content. By iteratively suppressing asymmetrically dispersed complex conjugate artifacts of OCT-signal pulses the complex valued signal can be recovered without additional measurements, thus doubling the spatial signal range to cover the full positive and negative sampling range. Previously the computational complexity and low processing speed limited application of DEFR to smaller amounts of data and did not allow ...

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    8. Graphics processing unit based dispersion encoded full-range frequency domain OCT

      Graphics processing unit based dispersion encoded full-range frequency domain OCT

      Standard FD-OCT systems suffer from a limited useful depth range due to the inherent complex conjugate artifacts and continuous fall-off in sensitivity with distance from the zero delay. The techniques of dispersion encoded full range (DEFR) frequency-domain optical coherence tomography (FD-OCT) and its enhanced version fast DEFR use the dispersion mismatch between sample and reference arm to double the imaging depth range by iteratively suppressing complex conjugate artifacts. Previously the computational complexity of DEFR prevented its application to fields where real-time visualization or large volumetric datasets are needed. A graphics processing unit (GPU) with hundreds of processing cores provides highly ...

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    9. Feature Of The Week 10/2/11: Heritability of Ocular Component Dimensions in Mice Phenotyped using Depth-Enhanced SS-OCT

      Feature Of The Week 10/2/11: Heritability of Ocular Component Dimensions in Mice Phenotyped using Depth-Enhanced SS-OCT
      Researchers based at Cardiff University and the Medical University of Vienna have taken advantage of the extended depth range delivered by swept source OCT to measure the eye size of mice with unprecedented precision [1].Measurement of eye size in humans is a standard medical procedure carried out before cataract removal surgery, which is perhaps the most commonly performed surgical operation in the world. The eye measurements are acquired using a laser Doppler interferometry (LDI) technique [2] closely related to time domain OCT.The length of the eye along its visual axis determines the refractive error of the eye. Myopia ...
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    10. Spectral phase based k-domain interpolation for uniform sampling in swept-source optical coherence tomography

      Spectral phase based k-domain interpolation for uniform sampling in swept-source optical coherence tomography

      We propose an efficient direct k-domain interpolation based on spectral phase in swept-source optical coherence tomography (SS-OCT). Both the calibration signal from the Mach-Zehnder interferometer (MZI) and the OCT imaging signal from the Michelson interferometer sharing the same swept source are detected and digitized simultaneously. Sufficient sampling of the OCT imaging signal with uniform k interval are directly interpolated in the k-domain based on the spectral phase derived from MZI calibration signal. Depth profile is then obtained from Fourier transform of the k-domain interpolated data. In vivo imaging of human finger skin and nail fold are conducted. Reconstructed images corresponding ...

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    11. Heritability of ocular component dimensions in mice phenotyped using depth-enhanced swept source optical coherence tomography

      Heritability of ocular component dimensions in mice phenotyped using depth-enhanced swept source optical coherence tomography
      The range of genetic and genomic resources available makes the mouse a powerful model for the genetic dissection of complex traits. Because accurate, high-throughput phenotypic characterisation is crucial to the success of such endeavours, we recently developed an optical coherence tomography (OCT) system with extended depth range scanning capability for measuring ocular component dimensions in mice. In order to test whether the accuracy and reproducibility of our OCT system was sufficient for gene mapping studies, we carried out an experiment designed to estimate the heritability of mouse ocular component dimensions. High-resolution, two dimensional tomograms were obtained for both eyes of ...
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    12. Highly reproducible swept-source, dispersion-encoded full-range biometry and imaging of the mouse eye

      Highly reproducible swept-source, dispersion-encoded full-range biometry and imaging of the mouse eye
      We report a high-speed, dispersion-encoded, full-range (DEFR) swept-source optical coherence tomography system for in vivo ocular imaging and biometry of small animals. The fast DEFR algorithm removes the depth ambiguity, gives access to objects located at the zero delay position, and doubles the sampling depth to 2×5.0 mm (at −101 to −71 dB sensitivity) in a single scan using 2048 samples/depth scan 0.43 nm line width of a light source operating at 1056 nm with 70 nm tuning range. The acquisition speed (frames of 512 depth scans in 18.3 ms) permits precise on-line monitoring during ...
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    13. Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm

      Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm

      The dispersion mismatch between sample and reference arm in frequency-domain optical coherence tomography (OCT) can be used to iteratively suppress complex conjugate artifacts and thereby increase the imaging range. In this paper, we propose a fast dispersion encoded full range (DEFR) algorithm that detects multiple signal components per iteration. The influence of different dispersion levels on the reconstruction quality is analyzed experimentally using a multilayered scattering phantom and in vivo retinal tomograms at 800 nm. Best results have been achieved with 30 mm SF11, with neglectable resolution decrease due to finite resolution of the spectrometer. Our fast DEFR algorithm achieves ...

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    14. Time-frequency distributions in spectroscopic Fourier-domain optical coherence tomography

      Current analysis for spectroscopic optical coherence tomography (SOCT) signals is limited by an uncertainty relationship between time (depth) and frequency (wavelength). Various joint time-frequency distributions (TFDs) can meliorate the limits to obtain the best information. Synthesized signals which correspond to three typical SOCT signals in the Fourier-domain under different SOCT imaging schemes, were generated and validate several different TFDs, including short time Fourier transform (STFT), continuous wavelet transform (CWT), Wigner-Villy distribution (WVD), and smoothed pseudo WVD (SPWVD). We found that different SOCT imaging scheme requires different optimal TFDs. STFT offers the most reliable and fast time-frequency (TF) analysis, which is ...
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    15. Wavelength encoded OCT imaging using swept-source

      Wavelength-encoded imaging uses wavelength division multiplexing to produce cross-sectional images without mechanical scanning, and could be of a great interest in endoscope applications. In this paper, a scheme for wavelength-encoded imaging using time-encoded Frequency-domain optical coherence tomography (swept-source optical coherence tomography, SS-OCT) is presented. This approach implements swept broadband source with narrow instantaneous spectral width and low dispersion diffraction grating to simultaneously produce depth-lateral imaging of the sample. Compared to previous spectral-domain wavelength-encoded endoscope, the proposed method enables high-speed and high dynamic range detection. System design such as image resolvable points, imaging resolution as well as theoretical analysis of the ...

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    16. High-speed spectral-domain optical coherence tomography at 830nm wavelength

      We present a high-speed spectral domain optical coherence tomography (SD-OCT) system at 830 nm wavelength which is consisted of a fiber based Michelson interferometer and a custom-built spectrometer. The designed resolution of the spectrometer is about 67.4pm which limits the maximum detection depth 2.56mm in air. And the 35us exposure time of the high speed line scan CCD makes real-time imaging possible. Furthermore, a novel method of spectrometer calibration is put forward. The method can remove the influence of dispersion mismatch, thus accurately determine the distribution of wavelength on the line scan CCD, which leads to a precise ...

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    1-16 of 16
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  2. Topics in the News

    1. (13 articles) Ling Wang
    2. (8 articles) Boris Považay
    3. (6 articles) Medical University of Vienna
    4. (6 articles) Cardiff University
    5. (6 articles) Bernd M. Hofer
    6. (5 articles) Wolfgang Drexler
    7. (5 articles) Jeremy A. Guggenheim
    8. (4 articles) Zhejiang University
    9. (4 articles) Zhihua Ding
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    Fast dispersion encoded full range optical coherence tomography for retinal imaging at 800 nm and 1060 nm Highly reproducible swept-source, dispersion-encoded full-range biometry and imaging of the mouse eye Heritability of ocular component dimensions in mice phenotyped using depth-enhanced swept source optical coherence tomography Spectral phase based k-domain interpolation for uniform sampling in swept-source optical coherence tomography Feature Of The Week 10/2/11: Heritability of Ocular Component Dimensions in Mice Phenotyped using Depth-Enhanced SS-OCT Graphics processing unit based dispersion encoded full-range frequency domain OCT Graphics processing unit-based dispersion encoded full-range frequency-domain optical coherence tomography In vivo evaluation of corneal biomechanical properties by optical coherence elastography at different cross-linking irradiances The Association of Optical Coherence Tomography Results With Neuroimaging Signs and Some Clinical Parameters in Idiopathic Intracranial Hypertension Low cost scalable monolithic common path probe design for the application in endoscopic optical coherence tomography Retinal and Choroidal Vascular Changes in Eyes with Pseudoexfoliation Syndrome: a Comparative Study Using Optical Coherence Tomography Angiography Longitudinal Detection of Radiation-Induced Peripapillary and Macular Retinal Capillary Ischemia Using Optical Coherence Tomography Angiography