1. Articles in category: Probes

    241-264 of 499 « 1 2 ... 8 9 10 11 12 13 14 ... 19 20 21 »
    1. Chemically Etched Single Mode Fiber Tip for High Lateral Resolution Imaging in Optical Coherence Tomography

      Chemically Etched Single Mode Fiber Tip for High Lateral Resolution Imaging in Optical Coherence Tomography

      In this paper, we propose a high lateral resolution common-path Fourier domain optical coherence tomography (OCT) system with the use of a chemically etched single mode fibre. In our experiments, a single mode optical fibre of 840 nm was used for preparing the tapered tips. Our system used a conical microlens that was chemically etched by a selective chemical etching technique using an etching solution of buffered hydrofluoric acid (BHF). From the experimental results, we verified that our proposed optical coherence tomography system could operate as a common-path Fourier domain OCT system and the apex angle of the chemically etched ...

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    2. Method and apparatus for monitoring blood constituent levels in biological tissue

      Method and apparatus for monitoring blood constituent levels in 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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    3. Optical Coherence Tomography And Illumination Using Common Light Source

      Optical Coherence Tomography And Illumination Using Common Light Source

      A light source for a surgical system includes a broadband light source operable to produce broadband light. The light source further includes a wavelength splitter adapted to split the broadband light into illumination light having a spectral range covering at least a majority of the visible spectrum and surgical light having a spectral range outside of the spectral range of the illumination light. The light source then includes at least one surgical module adapted to control application of the surgical light. The light source also includes first and second coupling optics. The first coupling optics are configured to optically couple ...

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    4. Enabling freehand lateral scanning of optical coherence tomography needle probes with a magnetic tracking system

      Enabling freehand lateral scanning of optical coherence tomography needle probes with a magnetic tracking system

      We present a high-resolution three-dimensional position tracking method that allows an optical coherence tomography (OCT) needle probe to be scanned laterally by hand, providing the high degree of flexibility and freedom required in clinical usage. The method is based on a magnetic tracking system, which is augmented by cross-correlation-based resampling and a two-stage moving window average algorithm to improve upon the tracker's limited intrinsic spatial resolution, achieving 18 µm RMS position accuracy. A proof-of-principle system was developed, with successful image reconstruction demonstrated on phantoms and on ex vivo human breast tissue validated against histology. This freehand scanning method could ...

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    5. Miniature actuator mechanism for intravascular imaging

      Miniature actuator mechanism for intravascular imaging

      The present invention relates to a new intravascular imaging device based on a Shape Memory Alloy (SMA) actuator mechanism embedded inside an elongate member such as a guide wire or catheter. The present invention utilizes a novel SMA mechanism to provide side-looking imaging by providing movement for an ultrasound transducer or optical coherence tomography (OCT) element. This novel SMA actuator mechanism can be easily fabricated in micro-scale, providing an advantage over existing imaging devices because it offers the ability to miniaturize the overall size of the device, while the use of multiple transducer crystals maximizes field of view of ultrasound ...

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    6. Intraoperative handheld optical coherence tomography forward-viewing probe: physical performance and preliminary animal imaging

      Intraoperative handheld optical coherence tomography forward-viewing probe: physical performance and preliminary animal imaging

      A prototype intraoperative hand-held optical coherence tomography (OCT) imaging probe was developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic probe was designed based on electrostatically driven optical fibers, and packaged into a catheter probe in the form factor of clinically accepted Bayonet shaped neurosurgical probes. Optical properties of the probe were measured to have a ~20 μm spot size, 5 mm working distance and 4 mm field of view. Feasibility of this probe for structural and Doppler shift imaging was tested on porcine femoral blood vessel imaging.

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    7. Methods and devices for image-guided manipulation or sensing or anatomic structures

      Methods and devices for image-guided manipulation or sensing or anatomic structures

      Forward-looking ultrasound transducers are positioned at the tip of a transseptal catheter to facilitate transseptal puncture and interventions within the left atrium, pulmonary veins and mitral valve. Catheter devices and systems are guided by forward-looking ultrasound or optical coherence tomography imaging for penetrating from one location within a mammalian patient's body to another location, and/or performing diagnostic or therapeutic interventions. A penetrator, diagnostic, or interventional device (eg. probe, biopsy apparatus, electrode, needle) is positioned at the catheter tip and is advanceable from the catheter to a target location outside of the lumen in which the catheter is positioned ...

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    8. Optical tomographic imaging system

      Optical tomographic imaging system

      The optical tomographic imaging system includes a main body for acquiring an optical tomographic image, an optical probe having a rotary optical fiber for guiding the measuring and returning light, a measuring unit, and a sheath rotatably holding the rotary optical fiber and the measuring unit, a rotary drive unit for rotatably coupling the rotary optical fiber to a stationary optical fiber connected with the main body, an extra length handling mechanism for winding the optical probe into a loop having at least a minimum diameter and an attaching unit removably attaching the optical probe. The extra length handling mechanism ...

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    9. Ultrathin fiber probes with extended depth of focus for optical coherence tomography

      Ultrathin fiber probes with extended depth of focus for optical coherence tomography

      We report on a novel scheme for extending the depth of focus (DOF) of ultrathin (125 μm diameter) fiber probes for optical coherence tomography (OCT) using a simple phase mask consisting of graded-index (GRIN) fiber. The technique is compatible with existing all-in-fiber probe fabrication techniques, and our simulations show that it can provide a DOF gain of ∼2 at a modest ∼5  dB reduction of peak sensitivity. In a prototype device using commercially available GRIN fiber, a DOF gain of 1.55 is obtained, validated by beam profiling and OCT imaging.

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    10. Optical structure measuring apparatus and optical probe thereof

      Optical structure measuring apparatus and optical probe thereof

      In an embodiment of the present invention, an OCT probe is configured by including: a thin and long substantially cylindrical sheath whose distal end is closed; an n-reflecting surface body, as an irradiating device, which has n reflecting surfaces (with n being an integer of three or more) and which is provided in a distal end portion of the sheath; a torque transmitting coil, as a rotating device, which is provided along the longitudinal axis of the sheath and which transmits rotational torque for rotating each of the reflection surfaces of the n-reflecting surface body about the longitudinal axis of ...

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    11. Real-time three-dimensional optical coherence tomography image-guided core-needle biopsy system

      Real-time three-dimensional optical coherence tomography image-guided core-needle biopsy system

      Advances in optical imaging modalities, such as optical coherence tomography (OCT), enable us to observe tissue microstructure at high resolution and in real time. Currently, core-needle biopsies are guided by external imaging modalities such as ultrasound imaging and x-ray computed tomography (CT) for breast and lung masses, respectively. These image-guided procedures are frequently limited by spatial resolution when using ultrasound imaging, or by temporal resolution (rapid real-time feedback capabilities) when using x-ray CT. One feasible approach is to perform OCT within small gauge needles to optically image tissue microstructure. However, to date, no system or core-needle device has been developed ...

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    12. Feature Of The Week 4/22/12: Novel MEMs-Driven OCT Endoscopic Imaging Probe Investigated by Singapore Researchers

      Feature Of The Week 4/22/12: Novel MEMs-Driven OCT Endoscopic Imaging Probe Investigated by Singapore Researchers

      Optical coherence tomography (OCT) has demonstrated its potential as a powerful imaging technology due to its cellular or even subcellular resolution (1-10 μm), which is considered suitable for early detection and diagnosis of cancer. For some clinic applications, for example, intravascular or gastrointestinal investigation, full circumferential scanning (FCS) is highly desired. Early research efforts on FCS such as spinning the entire catheter with build-in cables and fibers were capable of scanning at limited speeds with nonlinear motion due to the long cable rotation. Commercially-available micromotors have also been employed to spin mirrors or prisms to achieve FCS. In recent years ...

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    13. Towards a discretely actuated steerable cannula for diagnostic and therapeutic procedures

      Towards a discretely actuated steerable cannula for diagnostic and therapeutic procedures

      We have designed, developed, and evaluated the performance of a multi-degree-of-freedom discretely actuated steerable cannula with shape-memory alloy (SMA) actuators. This will enable us to deliver diagnostic as well as therapeutic devices to the target location through the hollow inner core of the cannula. We propose to use SMAs to generate bending forces due to its small size and high power density. We annealed the SMA wires through a customized training process in an arc shape and mounted them at discrete locations on the outer surface of the cannula to enable joint motion. A pulse-width modulation (PWM)-based control scheme ...

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    14. Miniature fiber-optic force sensor based on low-coherence Fabry-Pérot interferometry for vitreoretinal microsurgery

      Miniature fiber-optic force sensor based on low-coherence Fabry-Pérot interferometry for vitreoretinal microsurgery

      During vitreoretinal surgery, the surgeon manipulates retinal tissue with tool-to-tissue interaction forces below the human sensory threshold. A force sensor (FS) integrated with conventional surgical tools may significantly improve the surgery outcome by providing tactile feedback to the surgeon. We designed and built a surgical tool integrated with a miniature FS with an outer diameter smaller than 1 mm for vitreoretinal surgery based on low-coherence Fabry–Pérot (FP) interferometry. The force sensing elements are located at the tool tip which is in direct contact with tissue during surgery and the FP cavity length is interrogated by a fiber-optic common-path phase-sensitive ...

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    15. Rotational imaging probe safety mechanism for conditional rotational speed reduction

      Rotational imaging probe safety mechanism for conditional rotational speed reduction

      An image diagnostic system controls a probe to perform rotational and axially-moving scanning within a body cavity and to acquire reflected signals through the probe. Based on the acquired reflected signals, the system forms and outputs tomographic image of the body cavity and biotissue surrounding the body cavity. The system is provided with a detection unit which detects a direction of movement of the probe in the axially-moving scanning and a control unit which controls the rotational speed of the probe in the rotational scanning. The control unit includes a determination unit which determines whether or not the rotational speed ...

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    16. A compact circumferential scanned endoscopic imaging probe using a MEMS-driven pyramidal polygon reflector

      A compact circumferential scanned endoscopic imaging probe using a MEMS-driven pyramidal polygon reflector

      A novel prototype of electrothermal chevron-beam actuator based microelectromechanical systems (MEMS) platform has been successfully developed for circumferential scan. Microassembly technology is utilized to construct this platform, which consists of a MEMS chevron-beam type microactuator and a micro pyramidal polygon reflector. The proposed electrothermal microactuators with a two-stage electrothermal cascaded chevron-beam driving mechanism provide displacement amplification, and thus driving a highly reflective micro-pyramidal polygon reflector to rotate a large angle for light beam scan. This MEMS platform is ultra-compact, supports circumferential imaging capability, and is suitable for endoscopic optical coherence tomography (EOCT) application, for example intravascular cancer detection.

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    17. Improving treatment efficacy with biological or biophysical feedback

      Improving treatment efficacy with biological or biophysical feedback

      Optical measurements of tissue changes during photodynamic and radiation-based cancer treatments help to develop and improve these therapies.  Novel optical technologies can provide detailed microscopic information about tissue structure and physiology in a non-invasive manner, minimizing patient discomfort. This otherwise unobtainable information can help physicians select the best treatments, thus greatly benefiting patients. When used for early disease detection, it results in more effective curative therapies. It also allows inspection of the progress of various therapies to ensure they are working, enabling improvements to be made. We have investigated this last aspect of the benefits of optical methods, showing how ...

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    18. Miniature image guided three-axis scanning and positioning system

      Miniature image guided three-axis scanning and positioning system

      We have developed a high precision three axes scanning and positioning system for integration with Multifunctional Image Guided Surgical (MIGS) Platform. The stage integrates three main components: an optical coherence tomography (OCT) probe, laser scalpel and suction cup. The requirements for this stage were to provide scanning area of 400mm2, resolution of less than 10 microns and scanning velocity in the range of 10 - 40 mm/s. The stage was modeled using computer aided design software NX Unigraphics. In addition to the parameters mentioned above, additional boundary conditions for the stage were set as low volume and modularity. Optimized stage ...

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    19. Compact MEMS-driven pyramidal polygon reflector for circumferential scanned endoscopic imaging probe

      Compact MEMS-driven pyramidal polygon reflector for circumferential scanned endoscopic imaging probe

      A novel prototype of an electrothermal chevron-beam actuator based micro-electromechanical systems (MEMS) platform has been successfully developed for circumferential scan. Microassembly technology is utilized to construct this platform, which consists of a MEMS chevron-beam type microactuator and a micro-reflector. The proposed electrothermal microactuators with a two-stage electrothermal cascaded chevron-beam driving mechanism provide displacement amplification, thus enabling a highly reflective micro-pyramidal polygon reflector to rotate a large angle for light beam scanning. This MEMS platform is ultra-compact, supports circumferential imaging capability and is suitable for endoscopic optical coherence tomography (EOCT) applications, for example, for intravascular cancer detection.

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    20. Observation of Biological Tissues Using Common Path Optical Coherence Tomography with Gold Coated Conical Tip Lens Fiber

      Observation of Biological Tissues Using Common Path Optical Coherence Tomography with Gold Coated Conical Tip Lens Fiber

      In this paper, we proposed a high lateral resolution common-path Fourier domain optical coherence tomography(OCT) system with the use of a chemically etched single mode fiber. In our experiments, single mode optical fiber for 1310nm was used for preparing the tapered tips. Our system used a conical microlens that was chemically etched by selective chemical etching technique using an etching solution of buffered hydrofluoric acid (BHF). From experimental results, we verified that our proposed optical coherence tomography system could operate as a common-path Fourier domain OCT system and conical tip lens fiber was very useful for a high lateral ...

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    21. Feasibiliy of optical detection of soft tissue deformation during needle insertion

      Feasibiliy of optical detection of soft tissue deformation during needle insertion

      Needles provide an effective way to reach lesions in soft tissue and are frequently used for diagnosis and treatment. Examples include biopsies, tumor ablation, and brachytherapy. Yet, precise localization of the needle with respect to the target is complicated by motion and deformation of the tissue during insertion. We have developed a prototypical needle with an embedded optical fiber allowing to obtain optical coherence tomography images of the tissue in front of the needle tip. Using the data and particularly the Doppler information it is possible to estimate the motion of the needle tip with respect to the surrounding soft ...

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    22. Split-Frame Gimbaled Two-Dimensional MEMS Scanner for Miniature Dual-Axis Confocal Microendoscopes Fabricated by Front-Side Processing

      Split-Frame Gimbaled Two-Dimensional MEMS Scanner for Miniature Dual-Axis Confocal Microendoscopes Fabricated by Front-Side Processing

      In this paper, we introduce a 2-D microelectromechanical systems scanner for 3.2-mm-diameter dual-axis confocal microendoscopes, fabricated exclusively by front-side processing. Compared to conventional bulk micromachining that incorporates back-side etching, the front-side process is simple and thus enables high device yield. By eliminating the back-side etch window, the process yields compact and robust structures that facilitate handling and packaging. An important component of our front-side fabrication is a low-power deep reactive ion etching (DRIE) process that avoids the heating problems associated with standard DRIE. Reducing the RF etch coil power from 2400 to 1500 W leads to elimination of the ...

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    23. Modeling the effect of refraction on OCT imaging of lung tissue: a ray-tracing approach

      Modeling the effect of refraction on OCT imaging of lung tissue: a ray-tracing approach

      Determining the structure of lung tissue is difficult in ex-vivo samples. Optical coherence tomography (OCT) can image alveoli but ignores optical effects that distort the images. For example, light refracts and changes speed at the alveolar air-tissue surface. We employ ray-tracing to model OCT imaging with directional and speed changes included, using spherical shapes in 2D. Results show apparent thickening of inter-aveolar walls and distortion of shape and depth. Our approach suggests a correction algorithm by combining the model with image analysis. Distortion correction will allow inference of tissue mechanical properties and deeper imaging.

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    24. Neurosurgical hand-held optical coherence tomography (OCT) forward-viewing probe

      Neurosurgical hand-held optical coherence tomography (OCT) forward-viewing probe

      A prototype neurosurgical hand-held optical coherence tomography (OCT) imaging probe has been developed to provide micron resolution cross-sectional images of subsurface tissue during open surgery. This new ergonomic hand-held probe has been designed based on our group's previous work on electrostatically driven optical fibers. It has been packaged into a catheter probe in the familiar form factor of the clinically accepted Bayonet shaped neurosurgical non-imaging Doppler ultrasound probes. The optical design was optimized using ZEMAX simulation. Optical properties of the probe were tested to yield an ~20 um spot size, 5 mm working distance and a 3.5 mm ...

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    241-264 of 499 « 1 2 ... 8 9 10 11 12 13 14 ... 19 20 21 »
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