1. All Articles

    22681-22704 of 23346 « 1 2 ... 943 944 945 946 947 948 949 ... 971 972 973 »
    1. Enhanced optical coherence patterns of diabetic macular oedema and their correlation with the pathophysiology

      Enhanced optical coherence patterns of diabetic macular oedema and their correlation with the pathophysiology
      Purpose: To describe different patterns of diabetic macular oedema (DMO) using a computerized alignment and averaging of sequences in optical coherence tomography (OCT) B-scans and to show the correlation of these patterns with the pathophysiology of the condition. Methods: We carried out a prospective, uncontrolled study, including 46 human subjects with untreated DMO. Enhanced OCT images were produced. We correlated different OCT patterns of DMO with ETDRS visual acuity and with the thickness of the central 1-mm of the macula. We also correlated these patterns with theories of the pathophysiology of DMO. Results: Enhanced OCT images enabled us to examine ...
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    2. Simultaneous dual-band ultra-high resolution optical coherence tomography

      Simultaneous dual-band ultra-high resolution optical coherence tomography
      Ultra-high resolution optical coherence tomography (OCT) imaging is demonstrated simultaneously at 840 nm and 1230 nm central wavelength using an off-the-shelf turn-key supercontinuum light source. Spectral filtering of the light source emission results in a double peak spectrum with average powers exceeding 100 mW and bandwidths exceeding 200 nm for each wavelength band. A free-space OCT setup optimized to support both wavelengths in parallel is introduced. OCT imaging of biological tissue ex vivo and in vivo is demonstrated with axial resolutions measured to be < 2 μm and < 4 μm at 840 nm and 1230 nm, respectively. This measuring scheme is ...
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    3. Technical Note: Method for estimating volume of subretinal fluid in cases of localized retinal detachment by OCT ophthalmoscopy

      The volume of the subretinal fluid can be used to assess the condition of different types of retinal and macular disorders. The purpose of this report is to introduce a method to measure the volume of the subretinal fluid with the images of the optical coherence tomography (OCT) Ophthalmoscope in three cases of central serous chorioretinopathy and one case of retinal pigment epithelial detachment. We used the topography-mode program of the OCT Ophthalmoscope and measured the average height of the retinal detachment. By multiplying the size of the area of the retinal detachment and the average height of the retinal ...
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    4. Enzymatic vitreolysis with recombinant microplasminogen and tissue plasminogen activator

      Purpose To generate microplasmin (Plm) using recombinant microplasminogen (Plg) and recombinant tissue plasminogen activator (rt-PA) before intravitreous injection and to investigate the efficacy of Plm in inducing posterior vitreous detachment (PVD). Methods Forty-eight female or male New Zealand white rabbits were randomized into three groups. Recombinant human Plg was incubated with rt-PA with a 200:1 molar ratio at 37°C for 40 min. The right eyes of groups 1, 2, and 3, were injected with 0.5, 1.0, and 1.5 U Plm in 0.1 ml respectively, and 0.1 ml balanced salt solution (BSS) was injected ...

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      Mentions: Fudan University
    5. Method and apparatus for performing second harmonic optical coherence tomography

      The invention is an apparatus and method for second harmonic optical coherence tomography of a sample comprising a laser coupled to an interferometer which has a reference arm and in a sample arm. A nonlinear crystal in the reference arm generates a second harmonic reference signal. The sample typically backscatters some second harmonic light into the sample arm. A broadband beam splitter optically coupled to the reference arm and sample arm combines the signals from the reference arm and sample arm into interference fringes and a dichroic beam splitter splits the interference fringes into a fundamental and second harmonic interference ...
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    6. Clinical applications and new developments of optical coherence tomography: an evidence-based review

      Optical coherence tomography (OCT) is a new imaging modality that has increasingly become an indispensable tool in clinical practice for the diagnosis and management of ocular diseases involving the macula, optic nerve and anterior segment. The instrument is an advanced imaging technique that provides unprecedented high resolution and cross-sectional tomographic images of the ocular microstructure in situ, and in real time. Since its introduction about four years ago, a multitude of advantages has made OCT an essential instrument in ophthalmic imaging. The technique has fast image acquisition speed and non-contact, non-invasive applicability, allowing a non-excisional ‘optical biopsy’ to be performed ...
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    7. Method and apparatus for monitoring glucose levels in a biological tissue

      In accordance with the invention, a low coherence interferometer is used to non-invasively monitor the concentration of glucose in blood by shining a light over a surface area of human or animal tissue, continuously scanning the light over a two dimensional area of the surface, collecting the reflected light from within the tissue and constructively interfering this reflected light with light reflected along a reference path to scan the tissue in depth. Since the reflection spectrum is sensitive to glucose concentration at particular wavelengths, measurement and analysis of the reflected light provides a measure of the level of glucose in ...
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    8. Systems and methods for transforming video images using fast visual interpolation

      In an image gathering and display system, data is interpolated by gathering non-interpolated input data and formatting that data such that a user of the data can interpolate the data without requiring the image gathering and display system to perform the interpolation. A series of weighted randomly selected non-interpolated input data values are displayed to the user as a stream of non-interpolated output values, such that the user interpolates the series of non-interpolated output values.
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    9. Pathological tissue detection and treatment employing targeted benzoindole optical agents

      Novel tumor specific phototherapeutic and photodiagnostic agents are disclosed. The compounds consist of a carbocyanine dye for visualization, photosensitizer for photodynamic treatment, and tumor receptor-avid peptide for site-specific delivery of the probe and phototoxic agent to diseased tissues. A combination of these elements takes full advantage of the unique and efficient properties of each component for an effective patient care management.
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    10. Internal Scanning in Real-time: Video of Santec OCT System

      Image looking inside an object in real time. This device can dynamically display the surface as well as the optical coherence of 2D and 3D images, at the same level of clarity as with X-ray CT scanners, MRI machines, and ultrasonic confocal microscopes. The Optical Coherence Tomography is composed of probes, a scanning laser unit, and a high-speed computer for measuring and analyzing and software. It features a broad-spectrum optical source with a much wider wavelength than a traditional one. It can quickly measure biological objects and industrial products (such as plastic goods, semiconductors, coating paints, and protective films) by ...
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    11. Optical-coherence tomography, extension to imaging of low coherence interferometry

      Adrian Gh. Podoleanu, Radu G. Cucu, John A. Rogers et al. Results are presented in using low coherence interferometry in quantifying the reflectivity and imaging of different objects, such as tissue, paintings and fruits. All images have been obtained using en-face flying spot technology. This allows simultaneous generation of optical coherence tomography ... [Proc. SPIE Int. Soc. Opt. Eng. 6785, 67851I (2007)] published Wed Aug 1, 2007.
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    12. Femtosecond ytterbium fiber laser with photonic crystal fiber for dispersion control

      A photonic-crystal fiber provides dispersion compensation in a soliton fiber laser. The anomalous dispersion provided by the photonic-crystal fiber permits construction of a femtosecond fiber laser at 1 .mu.m wavelength without prisms or diffraction gratings. The laser produces .about.100-fs pulses with 1 nJ energy, and is a major step toward environmentally-stable all-fiber devices at 1 .mu.m.
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      Mentions: NKT Photonics
    13. Scanning spectrum analyzer

      A system for spectral analysis of a multi-wavelength signal is disclosed. The illustrative embodiment of the present invention, like the prior art, uses a grating or prism to disperse the spectral components of a multi-wavelength signal, and then uses a reciprocating or rotating mirror to direct the spectral components, one at a time, into a photodetector. The illustrative embodiment uses a telescope between the grating and the mirror to improve the spectral resolution of the system.
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    14. Correlation of concurrent non-invasively acquired signals

      A non-invasive imaging and analysis system suitable for measuring attributes of a target, such as the blood glucose concentration of tissue, includes an optical processing system which provides a probe and reference beam. It also includes a means that applies the probe beam to the target to be analyzed, combines the probe and reference beams interferometrically, detects concurrent interferometric signals and correlates the detected signals with previously stored electronic data to determine the attribute of the target.
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    15. Optical image measuring apparatus

      Provided is an optical image measuring apparatus capable of easily changing a scanning interval of an object to be measured in a depth direction with high precision. The apparatus includes an interference optical system for superimposing signal light propagating through the object to be measured on reference light subjected to frequency shift to produce interference light, a reference mirror driving unit for driving a mirror to scan the object to be measured in the depth direction, shutters for sampling interference light beams, CCDs for storing charges for only a predetermined storage time and outputting electrical signals, a control unit for ...
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    16. Method and an apparatus for the simultaneous determination of surface topometry and biometry of the eye

      An apparatus (10, 10') for detecting the surface topography of a cornea (24) of an eye (22) by dynamic or static projection of a pattern onto the surface of the cornea and detection of the pattern reflected by the cornea, providing preferably simultaneous detection of at least one optical property of a layer disposed beneath the cornea.
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      Mentions: Adolf F. Fercher
    17. 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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    18. Method and apparatus for producing a multiple optical channel source from a supercontinuum generator for WDM communication

      A system and method for producing a multiple optical channel source (MOCS). The method includes producing the SC in a medium using at least one femto-second or pico-second optical input pump pulse; splitting input pump pulse or resultant output SC pulse(s) into a plurality of collinear pulses; applying a time delay .tau. between the least one of input pump pulse or SC pulses; and producing a MOCS by the spectral interference of the plurality of SC pulses. The system includes a laser producing femto-second or pico-second pump pulses, a medium with a high value of the .chi..sup.(3 ...
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    19. Optical coherence diagnostics for painting conservation

      Raffaella Fontana, Marco Bellini, Chiara Corsi et al. One of the most important and sometimes controversial stages of the conservation process is surface cleaning: decisions have to be made regarding partial or complete removal of varnish. Technical considerations include selection of a method that allows a great deal of control in the cleaning process ... [Proc. SPIE Int. Soc. Opt. Eng. 6618, 661808 (2007)] published Mon Jul 16, 2007.
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    20. Full-field high-speed optical coherence tomography system for evaluating multilayer and random tissues

      Igor Gurov, Alexey Karpets, Nikita Margariants et al. Testing the condition of art subjects plays important role in reservation of Cultural Heritage. Optical Coherence Tomography (OCT) is a promising tool for nondestructive cross-sectional evaluating internal structure of material samples like varnish layer of paintings. It is important to use high-spe ... [Proc. SPIE Int. Soc. Opt. Eng. 6618, 661807 (2007)] published Mon Jul 16, 2007.
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    21. Optical coherence tomography: non-destructive imaging and spectral information of pigments

      Gael Latour, Julien Moreau, Mady Elias et al. Optical Coherence Tomography (OCT) is a non-invasive and non-destructive technique which is very interesting for the study of works of art. Based on a Michelson interferometer, our device has been adapted for the recording of information in the visible range. This system allows three-dimensional ima ... [Proc. SPIE Int. Soc. Opt. Eng. 6618, 661806 (2007)] published Mon Jul 16, 2007.
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    22. Optical coherence tomography for art conservation and archaeology

      Haida Liang, Borislava Peric, Michael Hughes et al. Optical coherence tomography (OCT) is a fast scanning Michelson interferometer originally designed for in vivo imaging of the eye. In 2004, our group along with two other groups first reported the application of OCT to art conservation and archaeology. Since that time we have been conducting a proje ... [Proc. SPIE Int. Soc. Opt. Eng. 6618, 661805 (2007)] published Mon Jul 16, 2007.
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    23. Optical coherence tomography for varnish ablation monitoring

      Optical Coherence Tomography (OCT) is a new, fast-growing technique for non-contact and non-destructive imaging of semi-transparent objects. It has been recently used for diverse applications in art conservation subject - among others it is very well suited for varnish layer imaging and thus for monitoring of varnish removing process, including the laser ablation. In this study we show how to use the OCT technique to obtain the information required for the optimisation of the laser emission parameters like fluency and working regime, with respect to efficiency and safety of the ablation process. We also demonstrate application of the Spectral Optical Coherence ...
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    24. Contribution of various scattering orders to OCT images of skin

      Simulated OCT images of skin were obtained implementing Monte Carlo simulations. The multilayer skin model used in simulations was based on the experimental OCT images obtained at the wavelength of 910 nm. The following skin layers were considered in the model: stratum corneum, epidermis prickle layer, epidermis basal layer, dermis with upper plexus, dermis, and dermis with lower plexus. The images were obtained both with and without speckle accounting. The latter case is calculated from the envelopes of calculated interference signals while the former accounts for the interference fringe patterns. The contributions of least and multiple scattering, diffusive and non-diffusive ...
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    22681-22704 of 23346 « 1 2 ... 943 944 945 946 947 948 949 ... 971 972 973 »
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