1. Articles from Gargi Sharma

    1-11 of 11
    1. Portable Optical Coherence Elastography System With Flexible and Phase Stable Common Path Optical Fiber Probe

      Portable Optical Coherence Elastography System With Flexible and Phase Stable Common Path Optical Fiber Probe

      Biomechanical properties drive the functioning of cells and tissue. Measurement of such properties in the clinic is quite challenging, however. Optical coherence elastography is an emerging technique in this field that can measure the biomechanical properties of the tissue. Unfortunately, such systems have been limited to benchtop configuration with limited clinical applications. A truly portable system with a flexible probe that could probe different sample sites with ease is still missing. In this work, we report a portable optical coherence elastography system based on a flexible common path optical fiber probe. The common path approach allows us to reduce the ...

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    2. Novel input polarisation independent endoscopic cross polarised optical coherence tomography probe

      Novel input polarisation independent endoscopic cross polarised optical coherence tomography probe

      Lead by the original idea to perform noninvasive optical biopsies of various tissue, optical coherence tomography found numerous medical applications within the last two decades. The interference based imaging technique opens the possibility to visualise subcellular morphology up to an imaging depth of 3 mm and up to micron level axial and lateral resolution. The birefringence properties of the tissue are visualised with enhanced contrast using polarisation sensitive or cross polarised optical coherence tomography techniques. Although, it requires strict control over the polarisation states, resulting in several polarisation controlling elements. In this work, we propose a novel inputā€polarisaion independent ...

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    3. Input polarization-independent polarization-sensitive optical coherence tomography using a depolarizer

      Input polarization-independent polarization-sensitive optical coherence tomography using a depolarizer

      Polarization-sensitive optical coherence tomography is gaining attention because of its ability to diagnose certain pathological conditions at an early stage. The majority of polarization-sensitive optical coherence tomography systems require a polarization controller and a polarizer to obtain the optimal polarization state of the light at the sample. Such systems are prone to misalignment since any movement of the optical fiber normally coupled to the light source will change the polarization state of the incident beam. We propose and demonstrate an input polarization-independent polarization-sensitive optical coherence tomography system using a depolarizer that works for any input polarization state of the light ...

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    4. Swept source cross-polarized optical coherence tomography for any input polarized light

      Swept source cross-polarized optical coherence tomography for any input polarized light

      Cross polarized optical coherence tomography offers enhanced contrast in certain pathological conditions. Traditional cross-polarized optical coherence tomography systems require a defined input polarization and thus require several polarization controlling elements increasing the overall complexity of the system. Our proposed system requires a single quarter wave plate as a polarization controller thus simplifying the system significantly. Majority of Cross-polarized optical coherence tomography systems are spectrometer based which suffers from slow speed and low signal to noise ratio. In this work, we present a swept source based cross-polarized optical coherence tomography system that works for any input polarization state. The system was ...

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    5. All fiber polarization insensitive detection for spectrometer based optical coherence tomography using optical switch

      All fiber polarization insensitive detection for spectrometer based optical coherence tomography using optical switch

      Polarization dependent image artifacts are common in optical coherence tomography imaging. Polarization insensitive detection scheme for swept source based optical coherence tomography systems is well established but is yet to be demonstrated for all fiber spectrometer-based Fourier domain optical coherence tomography systems. In this work, we present an all fiber polarization insensitive detection scheme for spectrometer based optical coherence tomography systems. Images from chicken breast muscle tissue were acquired to demonstrate the effectiveness of this scheme for the conventional Fourier domain optical coherence tomography system.

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    6. Visualizing cellular markers of sensorineural hearing loss in the murine cochlea using micro-optical coherence tomography

      Visualizing cellular markers of sensorineural hearing loss in the murine cochlea using micro-optical coherence tomography

      Although sensorineural hearing loss (SNHL) affects 600 million people globally and its prevalence is increasing, therapies remain limited. Advances in therapy development for SNHL are slow because we do not possess a method for visualizing the cochlea’s interior in living humans and relating visualized pathology to a patient’s hearing ability. To this end, we are investigating the ability of micro-optical coherence tomography (µOCT), a low-coherence interferometric imaging technique that requires no contrast agent and improves upon standard OCT in resolution and depth of focus, to visualize the micron-sized cellular structures in the cochlea. We recently demonstrated µOCT’s ...

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    7. Contrast enhancement of microscopic birefringent crystals using polarization sensitive micro-optical coherence tomography

      Contrast enhancement of microscopic birefringent crystals using polarization sensitive micro-optical coherence tomography

      Background: Birefringent crystals such as cholesterol and monosodium urate have recently been identified as possible pharmacologic targets for the treatment of coronary artery disease. The size of these crystals can be very small (on the order of 1 µm), making them difficult to identify. To image these microscopic crystals and enhance contrast, we modified existing micro optical coherence tomography system so that it was capable of obtaining polarization-sensitive images (PS-µOCT). A spectrometer-based PS-µOCT system was developed using a 270 nm wide broadband light source centered at 765 nm. Light was polarized using a polarizer and coupled to a ...

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    8. Estimation and compensation of dispersion for high-resolution optical coherence tomography system

      Estimation and compensation of dispersion for high-resolution optical coherence tomography system

      Balanced reference-sample arm dispersion is critical in optical coherence tomography systems in order to attain images with the highest axial resolution. Here, an experimental method for the estimation and correction of dispersion in an optical coherence tomography system is presented. The system dispersion was computed from two optical coherence tomography images of the reference mirror that were symmetrically placed around the zero delay point. The method was tested using a broad bandwidth spectral domain optical coherence tomography system, compensating for the dispersion caused by a 3-mm-thick fused silica flat placed in the sample arm. Using our method, dispersion compensation was ...

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    9. In-line optical fiber metallic mirror reflector for monolithic common path optical coherence tomography probes

      In-line optical fiber metallic mirror reflector for monolithic common path optical coherence tomography probes

      Background and Objectives Endoscopic optical coherence tomography probes suffer from various artifacts due to dispersion imbalance and polarization mismatch between reference and sample arm light. Such artifacts can be minimized using a common path approach. In this work, we demonstrate a miniaturized common path probe for optical coherence tomography using an inline fiber mirror. Materials and Methods A common path optical fiber probe suitable for performing high-resolution endoscopic optical coherence tomography imaging was developed. To achieve common path functionality, an inline fiber mirror was fabricated using a thin gold layer. A commercially available swept source engine was used to test ...

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    10. Correlation between central foveal thickness as measured by OCT andHbA1c level in diabetes retinopathy

      Correlation between central foveal thickness as measured by OCT andHbA1c level in diabetes retinopathy

      bjectives: To evaluate the correlation between Glycosylated Haemoglobin (HbA1c) level and central foveal thickness measured by Optical coherence tomography (OCT) in patients with type 2 diabetes mellitus.Materials and methods:This was a retrospective single center study of 6 month duration including patients of pre-proliferative stage of type 2 diabetes mellitus. Clinically significant macular oedema (CSME) was diagnosed by using OCT. OCT examination by ‘RT optovue, Fremont, CA’ and HbA1c measured by specific high-pressure liquid chromatography methods. If patient have both eye macular oedema, eye with thicker macular oedema was used for statistical analysis. Exclusion of patients who received intraocular ...

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      Mentions: Optovue
    1-11 of 11
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  2. Topics in the News

    1. (6 articles) Massachusetts General Hospital
    2. (6 articles) Harvard University
    3. (4 articles) University of Erlangen
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    Correlation between central foveal thickness as measured by OCT andHbA1c level in diabetes retinopathy In-line optical fiber metallic mirror reflector for monolithic common path optical coherence tomography probes Estimation and compensation of dispersion for high-resolution optical coherence tomography system Contrast enhancement of microscopic birefringent crystals using polarization sensitive micro-optical coherence tomography Visualizing cellular markers of sensorineural hearing loss in the murine cochlea using micro-optical coherence tomography Micro-Optical Coherence Tomography for Endothelial Cell Visualization in the Coronary Arteries All fiber polarization insensitive detection for spectrometer based optical coherence tomography using optical switch Swept source cross-polarized optical coherence tomography for any input polarized light Input polarization-independent polarization-sensitive optical coherence tomography using a depolarizer Novel input polarisation independent endoscopic cross polarised optical coherence tomography probe Post-Doctoral and Graduate Student Research Positions at the University of Illinois Urbana-Champaign Multiscale correlation of microvascular changes on optical coherence tomography angiography with retinal sensitivity in diabetic retinopathy