1. Articles from Lei Zhang

    1-10 of 10
    1. Miniaturized precalibration-based Lissajous scanning fiber probe for high speed endoscopic optical coherence tomography

      Miniaturized precalibration-based Lissajous scanning fiber probe for high speed endoscopic optical coherence tomography

      We present a miniaturized precalibration-based forward-viewing Lissajous scanning fiber probe for high speed endoscopic optical coherence tomography (OCT). The probe is based on an asymmetric fiber cantilever driven by the piezoelectric bender to realize two-dimensional (2D) Lissajous scanning. The stability and repeatability of the Lissajous scanning trajectory of the probe is tested by a position sensitive detector (PSD)-based position calibration setup. The two orthogonal resonant frequencies of the cantilever are measured to be 167.2 and 121 Hz. A 25 µm focal spot is formed at the working distance of 5 mm by the graded-index (GRIN) lens, and the ...

      Read Full Article
    2. Side-viewing endoscopic imaging probe for swept source optical coherence tomography

      Side-viewing endoscopic imaging probe for swept source optical coherence tomography

      Endoscopic optical coherence tomography (OCT) has many promising applications in the fields of medical research and clinical diagnosis. In this letter, we present a side-viewing endoscopic OCT probe based on a gradient index (GRIN) lens with an air gap. By adjusting the length of the air gap the optical performance of the probe can be flexibly tuned. The quantitative relationships between the optical performance parameters of the probe and its structural parameters are theoretically analyzed by using the ABCD beam transfer matrix theory. The developed probe has a maximum diameter of 1.4 mm and a rigid length of 11 ...

      Read Full Article
    3. Calibration-free time-stretch optical coherence tomography with large imaging depth

      Calibration-free time-stretch optical coherence tomography with large imaging depth

      We demonstrate a calibration-free time-stretch optical coherence tomography (TS-OCT), based on an optical higher order dispersion compensation scheme, which substitutes the digital calibration with optical dispersion compensation. As a result, the acquired raw data can directly perform the Fourier transform, and data processing time is greatly reduced by 82%, compared with the digital calibration. Moreover, because of the high-sensitivity and calibration-free characteristics, the high-order dispersion compensation-based TS-OCT can increase sensitivity roll-off by 2.6 times to 6.91 mm/dB and effective imaging depth by 14.2% to 16 mm. The in vivo biological tissue imaging has been demonstrated, with ...

      Read Full Article
    4. Longitudinal detection of retinal alterations by visible and near-infrared optical coherence tomography in a dexamethasone-induced ocular hypertension mouse model

      Longitudinal detection of retinal alterations by visible and near-infrared optical coherence tomography in a dexamethasone-induced ocular hypertension mouse model

      The retina, as part of the central nervous system, has distinct anatomical and structural properties for its visual function. Light scattering spectroscopy, while widely used for tissue structural characterization and disease diagnosis, has been relatively unexplored in the living retina. Recently, we have developed a fiber-based visible and near-infrared optical coherence tomography system (vnOCT) for in vivo retinal imaging, to uniquely measure a spectroscopic marker (VN ratio) sensitive to nanoscale pathological changes. In the present study, we applied vnOCT in an animal model of glaucoma (dexamethasone-induced ocular hypertension mouse) and tested the capabilities of four optical markers, VN ratio, peripapillary ...

      Read Full Article
    5. Detection of Malignancy in Ocular Surface Lesions by Inverse Spectroscopic Optical Coherence Tomography and Two-Photon Autofluorescence

      Detection of Malignancy in Ocular Surface Lesions by Inverse Spectroscopic Optical Coherence Tomography and Two-Photon Autofluorescence

      Purpose : Advanced imaging is increasingly important in the diagnosis of ocular surface malignancy. Inverse spectroscopic optical coherence tomography (ISOCT) and two-photon autofluorescence microscopy (2P-AF) are emerging techniques capable of quantifying ultrastructural and metabolic changes, respectively. We aimed to detect malignancy in ocular surface lesions using ISOCT and 2P-AF. Methods : Portions of excised specimens from patients undergoing conjunctival biopsy at Boston Medical Center were imaged by ISOCT and/or 2P-AF, and submitted for histologic diagnosis. Lesions were categorized as malignant, premalignant (with dysplasia) or benign. ISOCT and 2P-AF findings were compared between categories. Results : Fourteen specimens from 13 patients were collected ...

      Read Full Article
    6. Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography

      Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography

      Purpose . To determine conjunctival overlap over the edge of soft contact lens and to visualize the peripheral postlens tear film (PoLTF) underneath soft contact lenses using ultrahigh-resolution optical coherence tomography (UHR-OCT). Methods . Twenty participants (4 males and 16 females, 23.0 ± 3.7 years) were fitted with two different types of soft contact lenses randomly. The limbus with lens was imaged with the UHR-OCT at the horizontal meridian every two hours up to 6 hours during lens wear. The conjunctival overlap was ranked as the percentage of the edge covered by the conjunctiva. The frequency of occurrence for visualized peripheral ...

      Read Full Article
    7. Automatic Quantitative Analysis of Bioresorbable Vascular Scaffold Struts in Optical Coherence Tomography Images Using Region Growing

      Automatic Quantitative Analysis of Bioresorbable Vascular Scaffold Struts in Optical Coherence Tomography Images Using Region Growing

      Bioresorbable vascular scaffolds are new-generation stents that reduce the risk of intimal hyperplasia and late stent thrombosis. Intravascular optical coherence tomography is an important technique to evaluate images about struts. Analyzing strut status, such as apposition and malapposition, is important for the follow-up treatment of patients. Traditionally, it has taken up to 8 hours to manually analyze the strut status. In this study, a new method is presented to detect and quantify struts automatically. Ten pullback runs containing 7720 struts were acquired to validate the algorithm. For apposed/malapposed stent struts, the sensitivity of the method was 93.0% and ...

      Read Full Article
    8. Oblique scanning laser microscopy for simultaneously volumetric structural and molecular imaging using only one raster scan

      Oblique scanning laser microscopy for simultaneously volumetric structural and molecular imaging using only one raster scan

      Multi-modal three dimensional (3D) optical imaging combining both structural sensitivity and molecular specificity is highly desirable in biomedical research. In this paper, we present a method termed oblique scanning laser microscopy (OSLM) to combine optical coherence tomography (OCT), for simultaneously volumetric structural and molecular imaging with cellular resolution in all three dimensions. Conventional 3D laser scanning fluorescence microscopy requires repeated optical sectioning to create z-stacks in depth. Here, the use of an obliquely scanning laser eliminates the z-stacking process, then allows highly efficient 3D OCT and fluorescence imaging by using only one raster scan. The current setup provides ~3.6 ...

      Read Full Article
    9. Early histological alteration of the retina following photocoagulation treatment in diabetic retinopathy as measured by spectral domain optical coherence tomography

      Early histological alteration of the retina following photocoagulation treatment in diabetic retinopathy as measured by spectral domain optical coherence tomography

      Abstract Purpose  To investigate the earliest histological changes of the retina after laser treatment of diabetic retinopathy by using Spectral domain optical coherence tomography (SD-OCT, Heidelberg Engineering, Heidelberg, Germany). Methods  This study examined 320 laser burns from 16 eyes of 12 patients with early severe non-proliferative diabetic retinopathy (NPDR) that underwent laser photocoagulation according to the protocol which the Early Treatment Diabetic Retinopathy Study (ETDRS) recommended. SD-OCT scan was performed before the laser treatment, then 1 hour, 24 hours, 48 hours, 72 hours and 1 week after treatment. The main outcome measure was thickness change in outer retina (OR) in ...

      Read Full Article
    10. Ultra-broadband light source for optical coherence tomography by fiber matching

      In this paper, an ultra-broadband all fiber light source for optical coherence tomography was obtained. This light source was obtained by supercontinuum (SC) generated in matched fibers with different characteristics. It was showed that the spectrum quality was affected by dispersion and nonlinear characteristics of the fiber pumped firstly. SC spectrum flatness on the short wavelength side of pumping wavelength was affected by characteristic of the fiber pumped secondly. Dispersion shifted fiber (DSF) was connected after highly nonlinear fiber (HNLF) to optimize spectral shape. Widely broadened SC spectrum was generated in the combination of 120m HNLF+4.5km DSF+2km ...
      Read Full Article
    1-10 of 10
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (3 articles) Boston University
    2. (3 articles) Ji Yi
    3. (1 articles) Tianjin University
    4. (1 articles) Nanjing University of Science and Technology
    5. (1 articles) Wenzhou Medical College
    6. (1 articles) Meixiao Shen
    7. (1 articles) National Taiwan University
    8. (1 articles) Singapore Eye Research Institute
    9. (1 articles) Columbia University
    10. (1 articles) Seoul National University
    11. (1 articles) UT Southwestern Medical Center
    12. (1 articles) Donald C. Hood
    13. (1 articles) K. Bailey Freund
    14. (1 articles) Carl Zeiss Meditec
    15. (1 articles) Apollo Medical Optics
  3. Popular Articles

  4. Picture Gallery

    Early histological alteration of the retina following photocoagulation treatment in diabetic retinopathy as measured by spectral domain optical coherence tomography Oblique scanning laser microscopy for simultaneously volumetric structural and molecular imaging using only one raster scan Automatic Quantitative Analysis of Bioresorbable Vascular Scaffold Struts in Optical Coherence Tomography Images Using Region Growing Characterization of Soft Contact Lens Edge Fitting during Daily Wear Using Ultrahigh-Resolution Optical Coherence Tomography Detection of Malignancy in Ocular Surface Lesions by Inverse Spectroscopic Optical Coherence Tomography and Two-Photon Autofluorescence Longitudinal detection of retinal alterations by visible and near-infrared optical coherence tomography in a dexamethasone-induced ocular hypertension mouse model Calibration-free time-stretch optical coherence tomography with large imaging depth Side-viewing endoscopic imaging probe for swept source optical coherence tomography Miniaturized precalibration-based Lissajous scanning fiber probe for high speed endoscopic optical coherence tomography Forward genetic analysis using OCT screening identifies Sfxn3 mutations leading to progressive outer retinal degeneration in mice Optical coherence tomography characteristics of taxane-induced macular edema and other multimodal imaging findings Comparison of different morphologies of choroidal neovascularization evaluated by optical coherence tomography angiography in age‐related macular degeneration