1. Articles from Alexandre R. Tumlinson

    1-16 of 16
    1. Systems and methods for improved OCT measurements

      Systems and methods for improved OCT measurements

      Various systems and methods for sequential angle illumination to achieve ultra-high resolution optical coherence tomography (OCT) images. One example OCT system includes a light source, a beam divider, sample arm optics, a detector, and a processor. The light source generates a light beam to illuminate the sample. The beam divider separates the light beam into reference and sample arms. The sample arm optics sequentially illuminates a location in the sample with the light beam from different angles. The detector receives light returned from the reference arm and the sample illuminated at each angle and generates signals. The processor combines the ...

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    2. Optophysiological Characterisation of Inner Retina Responses with High-Resolution Optical Coherence Tomography

      Optophysiological Characterisation of Inner Retina Responses with High-Resolution Optical Coherence Tomography

      Low coherence laser interferometry has revolutionised quantitative biomedical imaging of optically transparent structures at cellular resolutions. We report the first optical recording of neuronal excitation at cellular resolution in the inner retina by quantifying optically recorded stimulus-evoked responses from the retinal ganglion cell layer and comparing them with an electrophysiological standard. We imaged anaesthetised paralysed tree shrews, gated image acquisition, and used numerical filters to eliminate noise arising from retinal movements during respiratory and cardiac cycles. We observed increases in contrast variability in the retinal ganglion cell layer and nerve fibre layer with flash stimuli and gratings. Regions of interest ...

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    3. Line-field holoscopy

      Line-field holoscopy

      A novel imaging method, line-field holoscopy is presented. A line of light is projected across an object to be investigated through an imaging system. The light scattered from the investigated object is combined with reference radiation. The combined light is projected onto a detector providing a confocal restriction in one dimension. Astigmatic optics in the return path transform the light asymmetrically such that at the detector, the line focus is imaged to the confocal restriction, while the orthogonal direction is defocused. Embodiments including a swept source with linear detection array, and spectrometer based systems utilizing a 2D detector array are ...

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    4. Systems and methods for sub-aperture based aberration measurement and correction in interferometric imaging

      Systems and methods for sub-aperture based aberration measurement and correction in interferometric imaging

      Systems and methods for sub-aperture correlation based wavefront measurement in a thick sample and correction as a post processing technique for interferometric imaging to achieve near diffraction limited resolution are described. Theory, simulation and experimental results are presented for the case of full field interference microscopy. The inventive technique can be applied to any coherent interferometric imaging technique and does not require knowledge of any system parameters. In one embodiment of the present invention, a fast and simple way to correct for defocus aberration is described. A variety of applications for the inventive method are presented.

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    5. Systems and methods for improved acquisition of ophthalmic optical coherence tomography data

      Systems and methods for improved acquisition of ophthalmic optical coherence tomography data

      Systems and methods for improved acquisition of ophthalmic optical coherence tomography data are presented, allowing for enhanced ease of use and higher quality data and analysis functionality. Embodiments include automated triggering for detecting and initiating collection of OCT ophthalmic data, an automated technique for determining the optimal number of B-scans to be collected to create the highest quality image and optimize speckle reduction, automated review of fundus images collected with an adjunct imaging modality to guide the OCT data collection, a single scan protocol in which a large field of view is collected with HD B-scans embedded at different locations ...

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    6. Optical Coherence Tomography System

      Optical Coherence Tomography System

      An OCT system comprises an OCT scan module for retinal scanning and an add-on anterior segment scanning module which includes at least one anterior segment scan lens (11) and an add-on fixation target (15) which is used to maintain the viewing direction of the eye (6) under investigation while achieving anterior segment scanning.

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    7. Systems And Methods For Variable Mode Optical Coherence Tomography Imaging

      Systems And Methods For Variable Mode Optical Coherence Tomography Imaging

      Systems and methods for improvements to optical coherence tomography systems for operating in different imaging modes are presented. In one embodiment, a system for identifying the presence and type of an adjunct lens operably connected to the OCT instrument for changing between imaging modes in the system is described. In a second embodiment, a system for dynamically autofocusing the OCT system depending on the layer of interest is presented.

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    8. Systems And Methods For SWEPT-SOURCE Optical Coherence Tomography

      Systems And Methods For SWEPT-SOURCE Optical Coherence Tomography

      Systems and methods for increasing the duty cycle and/or producing interleaved pulses of alternating polarization states in swept-source optical coherence tomography (OCT) systems are considered. Embodiments including improved buffering, frequency selecting filter sharing among multiple SOAs, intracavity switching, and multiple wavelength bands are described. The unique polarization properties of the source configurations have advantages in speckle reduction, polarization-sensitive measurements, polarization state dependent phase shifts, spatial shifts, and temporal shifts in OCT measurements.

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    9. Techniques for extraction of depth-resolved in vivo human retinal intrinsic optical signals with optical coherence tomography

      Purpose To demonstrate acquisition and analysis methods for depth-resolved observation of slow retinal physiology induced changes in infrared backscatter in vivo. Methods A dark-adapted human was briefly subjected to a localized photobleach. For 20 min before and 30 min after the stimulus, volumetric optical coherence tomograms were collected partially overlapping the bleached region. Tomograms were segmented into retinal layers by a newly described algorithm exploiting information in adjacent B-scans. En face fundus images extracted from major intraretinal layers were laterally registered manually. Time series summarizing the observed backscatter in selected layers for the bleached and unbleached areas are shown with ...
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    10. Impact of enhanced resolution, speed and penetration on three-dimensional retinal optical coherence tomography

      Impact of enhanced resolution, speed and penetration on three-dimensional retinal optical coherence tomography
      Recent substantial developments in light source and detector technology have initiated a paradigm shift in retinal optical coherence tomography (OCT) performance. Broad bandwidth light sources in the 800 nm and 1060 nm wavelength region enable axial OCT resolutions of 2-3 μm and 5-7 ... [Opt. Express 17, 4134-4150 (2009)]
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    11. Inherent homogenous media dispersion compensation in frequency domain optical coherence tomography by accurate k-sampling

      Alexandre R. Tumlinson, Bernd Hofer, Amy M. Winkler, Boris Považay, Wolfgang Drexler, Jennifer K. Barton. Depth dependent broadening of the axial point spread function due to dispersion in the imaged media, and algorithms for postprocess correction, have been previously described for both time domain and frequency domain optical coherence tomography. We show that homogeneous media dispersion artifacts ... [Appl. Opt. 47, 687-693 (2008)]
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    12. Scatter sensitive microscopic techniques to identify contrasting mucosal structures in ultrahigh-resolution optical coherence tomograms of mouse colon

      Alexandre R. Tumlinson, Lida P. Hariri, Wolfgang Drexler et al. Optical coherence tomography, optical coherence microscopy, reflectance confocal microscopy, and darkfield microscopy all derive contrast from the intensity of endogenous tissue scatter. We have imaged excised mouse colon tissue with these complimentary technologies to make conclusions about structu ... [Proc. SPIE Int. Soc. Opt. Eng. 6851, 68510A (2008)] published Tue Feb 5, 2008.
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    13. Serial Endoscopy in Azoxymethane Treated Mice Using Ultra-High Resolution Optical Coherence Tomography

      Serial Endoscopy in Azoxymethane Treated Mice Using Ultra-High Resolution Optical Coherence Tomography

      Purpose: Optical coherence tomography (OCT) is a minimally invasive, depth-resolved imaging tool that can be implemented in a small diameter endoscope for imaging mouse models of colorectal cancer (CRC). In this study, we utilized ultrahigh resolution (UHR) OCT to serially image the lower colon of azoxymethane (AOM) treated A/J mouse models of CRC in order to monitor the progression of neoplastic transformations and determine if OCT is capable of identifying early disease. Experimental Design: Thirteen AOM treated A/J and two control A/J mice were surveyed at four timepoints (8, 14, 22, and 26 weeks post AOM treatment ...

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    14. Ultrahigh-Resolution Endoscopic Optical Coherence Tomography for In Vivo Mouse Colonoscopy (Thesis)

      Ultrahigh-Resolution Endoscopic Optical Coherence Tomography for In Vivo Mouse Colonoscopy (Thesis)
      In vivo monitoring of mouse models of colon cancer promises to reduce the cost of research by improving sacrifice timing and allowing serial studies that observe the progression of disease and drug efficacy in a relatively small set of animals. Optical coherence tomography (OCT) is an optical analog of ultrasound imaging, capable of minimally-invasive mapping of light scatter intensity up to 2 mm deep in tissue. In this work, factors limiting resolution in OCT were examined and devices were created and applied to mouse colon imaging that extended the state-of-the-art in endoscopic ultrahigh-resolution OCT. First, axial chromatic aberration of the ...
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    15. Endoscopic optical coherence tomography and laser-induced fluorescence spectroscopy in a murine colon cancer model

      Background and Objectives The diagnostic feasibility of optical coherence tomography (OCT) and laser-induced fluorescence (LIF) have been evaluated for human colorectal cancer. This study applies these technologies to a murine model of colorectal adenoma. Study Design/Materials and Methods The lower colon of 10 ApcMin and two C57BL/6J mice was surveyed over five 4-week intervals using a prototype 2.0 mm diameter OCT-LIF endoscope-based system. Four categories were histologically classified: control C57BL/6J, adenomatous, non-diseased regions of adenomatous, and non-diseased ApcMin. OCT images were compared to histology. Spectra from the four categories were compared via the Student's t-test ...

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    16. Miniature Endoscope for Simultaneous Optical Coherence Tomography and Laser-Induced Fluorescence Measurement

      We have designed a multimodality system that combines optical coherence tomography (OCT) and laser-induced fluorescence (LIF) in a 2.0-mm-diameter endoscopic package. OCT provides ~18-μm resolution cross-sectional structural information over a 6-mm field. LIF spectra are collected sequentially at submillimeter resolution across the same field and provide histochemical information about the tissue. We present the use of a rod prism to reduce the asymmetry in the OCT beam caused by a cylindrical window. The endoscope has been applied to investigate mouse colon cancer in vivo.
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    1-16 of 16
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  2. Topics in the News

    1. (15 articles) Alexandre R. Tumlinson
    2. (7 articles) Carl Zeiss Meditec
    3. (6 articles) University of Arizona
    4. (6 articles) Jennifer K. Barton
    5. (6 articles) Wolfgang Drexler
    6. (4 articles) Cardiff University
    7. (4 articles) Lida P. Hariri
    8. (4 articles) Boris Považay
    9. (3 articles) Bernd M. Hofer
    10. (3 articles) Matthew J. Everett
    11. (1 articles) Samsung
    12. (1 articles) Johns Hopkins University
    13. (1 articles) National Institutes of Health
    14. (1 articles) Sungkyunkwan University
    15. (1 articles) University of São Paulo
    16. (1 articles) Massachusetts Institute of Technology
    17. (1 articles) L V Prasad Eye Institute
    18. (1 articles) Gong Je Seong
    19. (1 articles) Chan Yun Kim
    20. (1 articles) James G. Fujimoto
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    Impact of enhanced resolution, speed and penetration on three-dimensional retinal optical coherence tomography Serial Endoscopy in Azoxymethane Treated Mice Using Ultra-High Resolution Optical Coherence Tomography Ultrahigh-Resolution Endoscopic Optical Coherence Tomography for In Vivo Mouse Colonoscopy (Thesis) Systems And Methods For SWEPT-SOURCE Optical Coherence Tomography Line-field holoscopy Factors Associated with Changes in Retinal Layers Following Acute Optic Neuritis: A Longitudinal Study Using Optical Coherence Tomography Relationship between N95 Amplitude of Pattern Electroretinogram and Optical Coherence Tomography Angiography in Open-Angle Glaucoma Historic Effort to 'End Blindness" Marks a Major Milestone with Leading Scientist Recognized for Pioneering Work at VIP Ceremony Featuring Tribute to Ruth Bader Ginsburg Healing and early stent coverage after ultrathin strut biodegradable polymer‐coated sirolimus‐eluting stent implantation: SiBi optical coherence tomography study Influences of hypomagnesemia on optic nerve and retinal vascular structure determined using optical coherence tomography angiography Repeatability and agreement of total corneal and sublayer pachymetry with 2 different algorithms of Fourier-domain optical coherence tomography in myopic and postphotorefractive keratectomy eyes Vessel Density around Foveal Avascular Zone as a Potential Imaging Biomarker for Detecting Preclinical Diabetic Retinopathy: An Optical Coherence Tomography Angiography Study