A5100446451- Optical Coherence Tomography Applications
- Advanced Fluorescence Microscopy Techniques
- Photoacoustic and Ultrasonic Imaging
- Glaucoma and retinal disorders
- Corneal surgery and disorders
- Retinal and Macular Surgery
- Optical Polarization and Ellipsometry
- Coronary Interventions and Diagnostics
- Retinal Imaging and Analysis
- Retinal Diseases and Treatments
- Image Processing Techniques and Applications
- Optical Imaging and Spectroscopy Techniques
- Orbital Angular Momentum in Optics
- Power Line Inspection Robots
- Advanced Image Processing Techniques
- Prosthetics and Rehabilitation Robotics
- Plant Pathogens and Fungal Diseases
- Ophthalmology and Visual Impairment Studies
- Cell Adhesion Molecules Research
- Belt Conveyor Systems Engineering
- Spectroscopy Techniques in Biomedical and Chemical Research
- Robot Manipulation and Learning
- Corneal Surgery and Treatments
- Welding Techniques and Residual Stresses
- RNA Interference and Gene Delivery
Singapore Eye Research Institute
2019-2025
Singapore National Eye Center
2020-2025
Duke-NUS Medical School
2022-2025
Nanyang Technological University
2014-2022
Advanced Engineering (Czechia)
2021
Zhejiang University
2021
A*STAR Graduate Academy
2020
Xi'an Shiyou University
2018
Harbin Institute of Technology
2016
In this paper, we report what believe is a novel technique to overcome the depth-of-focus (DOF) limitation in optical coherence tomography (OCT).Using confocal optics on sample arm, scanned illumination beam across under-filled objective lens pupil plane by steering at pinhole using microcylindrical lens.The detected interferometric signals from multiple distinctive apertures were digitally refocused, which analogous synthetic aperture radar (SAR).Using numerical simulations and imaging...
Abstract In myopic eyes, pathological remodelling of collagen in the posterior sclera has mostly been observed ex vivo. Here we report development triple-input polarization-sensitive optical coherence tomography (OCT) for measuring scleral birefringence. guinea pigs and humans, technique offers superior imaging sensitivities accuracies than dual-input OCT. 8-week-long studies with young pigs, birefringence was positively correlated spherical equivalent refractive errors predicted onset...
Diagnosis of corneal disease and challenges in transplantation require comprehensive understanding anatomy, particularly that the posterior cornea. Micro-optical coherence tomography (µOCT) is a potentially suitable tool to meet this need, owing its ultrahigh isotropic spatial resolution, high image acquisition rate depth priority scanning mode. In study, we explored ability µOCT visualize micro-anatomical structures cornea ex vivo using small large animals. clearly delineated layers...
The depth reflectivity profile of Fourier domain optical coherence tomography (FD-OCT) is estimated from the inverse transform spectral interference signals (interferograms). As a result, axial resolution fundamentally limited by length light source. We demonstrate that using autoregressive estimation technique instead transform, to analyze interferograms can improve resolution. name this method OCT (SE-OCT). SE-OCT breaks limitation and improves factor up 4.7 compared with FD-OCT....
1 μm axial resolution spectral domain optical coherence tomography (OCT) is demonstrated for in vivo cellular imaging. Output of two superluminescent diode sources combined to provide near infrared illumination from 755 1105 nm. The interference detected using spectrometers based on a Si camera and an InGaAs camera, respectively. Spectra the are achieve 1.27 air. Imaging was conducted zebra fish larvae visualize details.
Abstract Recent developments in optical coherence tomography (OCT) systems for the cornea have limited resolution or acquisition speed. In this study we aim to evaluate use of a ‘micro-OCT’ (μOCT ~1 μm axial resolution) compared existing imaging modalities using animal models corneal endothelial disease. We used established cryoinjury and bullous keratopathy Sprague Dawley rats comparing ex vivo μOCT normal diseased eyes (1) histology; (2) confocal microscopy (IVCM); (3) scanning electron...
SignificanceCurrent methods for complex conjugate removal (CCR) in frequency-domain optical coherence tomography (FD-OCT) often require additional hardware components, which increase system complexity and cost. A software-based solution would provide a more efficient cost-effective alternative.AimWe aim to develop deep learning approach effectively remove artifacts (CCAs) from OCT scans without the need extra components.ApproachWe introduce method that employs generative adversarial networks...
High resolution optical coherence tomography (OCT) is capable of providing detailed tissue microstructures that are critical for disease diagnosis, yet its sensitivity usually degraded since the system key components typically not working at their respective center wavelengths. We developed a novel imaging achieves enhanced without axial degradation by use spectrally encoded extended source (SEES) technique; it allows larger sample power exceeding maximum permissible exposure (MPE). In this...
Birefringence imaging, including polarization sensitive optical coherence tomography (PS-OCT), can provide valuable insight into the microscopic structure and organization of many biological tissues. In this paper, we report on a method to fabricate tissue-like birefringence phantoms for such imaging modalities. We utilize photo-elastic effect, wherein is induced by stretching polymer sample after heating it above its glass-transition temperature. The cooled samples stably exhibit...
Abstract Spectral-domain optical coherence tomography (SDOCT) is the gold standard of imaging eye in clinics. Penetration depth with such devices is, however, limited and visualization choroid, which essential for diagnosing chorioretinal disease, remains limited. Whereas swept-source OCT (SSOCT) allow choroid these instruments are expensive availability praxis We present an artificial intelligence (AI)-based solution to enhance scans quantitative measurements choroidal metrics using...
Intravascular polarimetry with catheter-based polarization-sensitive optical coherence tomography (PS-OCT) complements the high-resolution structural tomograms of OCT morphological contrast available through polarimetry. Its clinical translation has been complicated by need for modification conventional hardware to enable polarimetric measurements. Here, we present a signal processing method reconstruct polarization properties tissue from measurements single input state, bypassing modulation...
We demonstrate a new focus engineering scheme to achieve both extended depth of (DOF) and sidelobe suppression in spectral-domain optical coherence tomography (SD-OCT) system. Each the illumination pupil function detection is modulated using an annular filter implemented by center obscuration. The two filters are arranged dark-field configuration such that first point-spread (PSF) matches minimum PSF lateral focal plane. tested feasibility proposed numerically, then constructed OCT (DF-OCT)...
We report on an integrated fiber optic design to implement multifiber angular compounding optical coherence tomography, which enables for speckle reduction. A multi-facet array delivers three light beams the sample with different incident angles. Back-reflective/back-scattered signals from these channels were simultaneously detected by a three-channel spectrometer. The axial and lateral resolution was measured be ∼3 ∼3.5 μm, respectively, in air ∼100 dB sensitivity. conducted ex vivo...
Heterogeneous Au–Fe3O4 dumbbell nanoparticles (NPs) are composed of Au NPs and Fe3O4 that bring in optical magnetic properties respectively. This article reports the engineering as gene carriers for transfection well contrast agents micro-optical coherence tomography (μOCT). As a proof-of-concept, used to deliver green fluorescent protein HEK 293T cells their entrance into is monitored through μOCT.
Our ability to detect neoplastic changes in gastrointestinal (GI) tracts is limited by the lack of an endomicroscopic imaging tool that provides cellular‐level structural details GI mucosa over a large tissue area. In this article, we report fiber‐optic‐based micro‐optical coherence tomography (μOCT) system and demonstrate its capability acquire through circumferential scanning. The achieves axial resolution 2.48 μm air transverse 4.8 with depth‐of‐focus (DOF) ~150 μm. To mitigate issue DOF,...
We developed a spectral domain optical coherence tomography (SD-OCT) to reduce auto-correlation artifacts (AC) using dual-balanced detection (DBD). AC were composed of the interference signals between different sample tissue depths, and shown up as in OCT images. This system employed free-space Michelson interferometer, at refraction plane whose beam splitter, light reflected experienced π/2 phase shift with respect transmitted. Then two phase-opposed interferometric spectra sharing same...
Nano-structures of biological systems can produce diverse spectroscopic effects through interactions with broadband light. Although structured coloration at the surface has been extensively studied, natural contrasts in deep tissues are poorly understood, which may carry valuable information for evaluating anatomy and function systems. Here we investigated characteristics an important geometry nanometer scale: packed nano-cylinders, near-infrared window, numerically predicted experimentally...
Plaque rupture is the critical cause of cardiovascular thrombosis, but detailed mechanisms are not fully understood. Recent studies have found abundant cholesterol crystals in ruptured plaques, and it has been proposed that rapid expansion a limited space during crystallization may contribute to plaque rupture. To evaluate effect crystal growth on atherosclerotic we modeled process necrotic core estimated stress thin cap with different arrangements crystals. We developed two-dimensional...
The mucosal microanatomy of the large intestine is characterized by presence crypts Lieberkühn, which associated predominantly with goblet cells. Such cellular-level intestinal microstructures undergo morphological changes during progression bowel diseases, such as colon cancer or ulcerative colitis. As an indicator gastric cancers, metaplasia in appearance cells epithelium, and therefore, visualization microstructure cross-sectional view, particularly vivo, a high-speed fashion would assist...
In fiber-based optical coherence tomography (OCT), the interference fringes suffer from fading effect due to misalignment of light polarization states between reference and sample arms, resulting in sensitivity degradation image intensity variation. We theoretically experimentally analyzed relation coefficient. Assuming that variation single-mode fiber (SMF) was a random process, we statistically quantified effect. Furthermore, OCT configuration based on Michelson interferometer, reported an...
Detecting early-stage epithelial cancers and their precursor lesions are challenging as could be subtle focally or heterogeneously distributed over large mucosal areas. Optical coherence tomography (OCT) that enables wide-field imaging of subsurface microstructures in vivo is a promising screening tool for diseases. However, its diagnostic capability has not been fully appreciated since the optical reflectance contrast poorly understood. We investigated back-scattered intensities from...
The refractive index of a biological tissue is required for investigating the tissue's optical properties. Efforts have been made to characterize indices tissues at single wavelength, but it more convenient know Cauchy's coefficients, which provide over wide range wavelengths. We demonstrate method noninvasively dispersion coefficients using micro-optical coherence tomography. Using short-frequency Fourier transforms, relative thickness sample in wavelength broadband source was obtained from...
Current optical coherence tomography (OCT) technology, which is used for imaging the eye's anterior segment, has been established as a clinical gold standard diagnosis of corneal diseases.However, cellular resolution level information that critical many applications still not available.The major technical challenges toward OCT are limited ranging depth and focus (DOF).In this work, we present novel ultrahigh system achieves an isotropic spatial <2 µm in tissue.The proposed could...