1. Articles in category: Probes

    241-264 of 486 « 1 2 ... 8 9 10 11 12 13 14 ... 19 20 21 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. A miniature forward-imaging optical coherence tomography (OCT) probe

      A miniature forward-imaging optical coherence tomography (OCT) probe

      Optical coherence tomography (OCT) has had a tremendous global health impact upon the current ability to diagnose, treat, and monitor multiple eye diseases. We propose that a miniature forward-imaging OCT probe can be developed for real-time ocular imaging. A miniature 25-gauge forward-imaging probe was designed and developed to use with an 850 nm spectral-domain optical coherence tomography (SDOCT) system (Bioptigen, Inc. Durham, NC). Imaging parameters were determined. Ocular tissues were examined with the miniature OCT probe. A miniature SDOCT probe was developed with the scanning driver within the hand piece. The SDOCT fiber-scanning probe maximally transmitted power of 800 μW ...

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    13. Fluorescence-based surface magnifying chromoendoscopy and optical coherence tomography endoscope

      Fluorescence-based surface magnifying chromoendoscopy and optical coherence tomography endoscope

      A side-viewing, 2 mm diameter, surface magnifying chromoendoscopy (SMC)-optical coherence tomography (OCT) endoscope has been designed for simultaneous, non-destructive surface fluorescence visualization and cross-sectional imaging. We apply this endoscope to in vivo examination of mouse colon. A 30,000 element fiber bundle is combined with single mode fibers. The distal optics consist of a gradient-index lens and spacer to provide a magnification of 1 at a working distance of 1.58 mm in air, necessary to image the sample through a 0.23 mm thick outer glass envelope, and an aluminized right-angle prism fixed to the distal end of ...

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    14. Polymer microlens fiber probe for common path optical coherence tomography

      Polymer microlens fiber probe for common path optical coherence tomography

      We demonstrate a compact all-fiber probe for a common path optical coherence tomography (CPOCT) system. By forming a focusing lens directly on the tip of an optical fiber, a compact fiber probe could be constructed. The microlens is produced by forming a droplet with UV-curing adhesive on the cleaved tip of multimode fiber. It fulfills two functions acting as both the reference plane and the imaging lens. To simultaneously achieve a relative long working distance and a good lateral resolution, we employed a large core size multimode fiber. A working distance of 280μm, and a transverse resolution of 14μm were ...

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    15. Motor and endoscope probe equipped with motor

      Motor and endoscope probe equipped with motor

      A motor which can be mounted in an endoscope probe without bending an electric power supply wire in an endoscope probe body, and an endoscope probe using the motor are provided. The motor includes a magnet, a field coil, a housing, an electric power supply wire, and a shaft. A lead wire from the field coil is connected to the electric power supply wire. A cutout is provided in a housing end, and the electric power supply wire is received along the cutout and led out to the outside of the motor in the direction in which a shaft projects ...

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    16. Diagnostic imaging system and processing method for producing reduced frame rate images from data collected at a higher frame rates

      Diagnostic imaging system and processing method for producing reduced frame rate images from data collected at a higher frame rates
      An image diagnostic system controls a probe to perform radial scanning within a body cavity and to acquire reflected signals through the probe. The system produces data based on the signals, constructs and outputs tomographic images of the body cavity and biotissue surrounding the body cavity. The system includes an extraction unit for extracting portions of the produced data on the basis of a frame rate upon successively outputting the tomographic images, and a first output control unit for forming, based on the extracted data, real time tomographic images of the body cavity and biotissue which are outputted in real ...
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    17. Image diagnostic apparatus and method

      Image diagnostic apparatus and method
      An image diagnostic apparatus includes a probe capable of light transmission and reception, wherein a reflection light is obtained from the probe by scanning the probe rotatingly, and a tomographic image is formed and outputted based on the obtained reflection light. A light-shield is provided to shield the light transmitted to the probe, a connection detector detects whether or not the probe is connected, and a controller controls the light-shield based on a detected result by the connection detector.
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    18. Congratulations to Jian Ren from Caltech a Winner of a 2012 Student Travel Grant Award

      Congratulations to Jian Ren from  Caltech a Winner of a 2012 Student Travel Grant Award
      Jian Ren from the California Institute of Technology is one of four winners of the OCT News 2012 student travel grant awards (see prior announcement Here). Below is a summary of his work. Glaucoma is one type of ophthalmic diseases, where ocular hypertension damages optical nerve, making it the second leading cause of blindness worldwide. One major cause of Open Angle Glaucoma is the poor outflow of aqueous humor through the Trabecular Meshwork (TM). Potential treatments include the micro-bypass stents, which are implanted in the TM and shunt fluid directly to the Schlemm’s Canal (SC) to reduce intraocular pressure ...
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    19. Double common-path interferometer for flexible optical probe of optical coherence tomography

      Double common-path interferometer for flexible optical probe of optical coherence tomography

      A flexible curled optical cord is useful for a common-path optical coherence tomography (OCT) system because a bending-insensitive arbitrary length can be chosen for the endoscopic imaging probe. However, there has been a critical problem that the partial reflector needs to be placed in between the sample and the objective lens. It limits the structure design of optical probe and leads to a low transverse resolution OCT imaging. Instead of a conventional single common-path interferometer, we propose a novel double common-path interferometer configuration in order to generate an interference signal that is independent of the optical distance between the partial ...

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    20. Refractive index measurement of acute rat brain tissue slices using optical coherence tomography

      Refractive index measurement of acute rat brain tissue slices using optical coherence tomography
      An optical coherence tomography (OCT) system employing a microelectromechanical system (MEMS) mirror was used to measure the refractive index (RI) of anatomically different regions in acute brain tissue slices, in which viability was maintained. RI was measured in white-matter and grey-matter regions, including the cerebral cortex, putamen, hippocampus, thalamus and corpus callosum. The RI in the corpus callosum was found to be ~4% higher than the RIs in other regions. Changes in RI with tissue deformation were also measured in the cerebral cortex and corpus callosum under uniform compression (20-80% strain). For 80% strain, measured RIs increased nonlinearly by up ...
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    21. Feature Of The Week 12/11/11: University of Western Australia Demonstrates Ultrathin Side-Viewing Needle Probe for Optical Coherence Tomography

      Feature Of The Week 12/11/11: University of Western Australia Demonstrates Ultrathin Side-Viewing Needle Probe for Optical Coherence Tomography

      Researchers at the University of Western Australia (UWA) have set a new record for the smallest side-viewing OCT imaging needle by demonstrating an ultrathin 30G needle probe with an outer diameter of only 0.31 mm. OCT needle probes [1, 2] are an enabling technology which allows to overcome the inherent imaging depth limitation of OCT of about 2-3 mm in biological tissue. To minimize tissue damage and deformation when imaging delicate organs or small animals, it is desirable to use very thin needle sizes.The ultrathin 30G needle probe presented in this work is based on a simple all-fiber ...

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    22. Imaging of Breast Cancer with Optical Coherence Tomography Needle Probes: Feasibility and Initial Results

      Imaging of Breast Cancer with Optical Coherence Tomography Needle Probes: Feasibility and Initial Results

      Optical coherence tomography (OCT) is a high-resolution imaging modality with the potential to provide in situ assessment to distinguish normal from cancerous tissue. However, limited image penetration depth has restricted its utility. This paper demonstrates the feasibility of an OCT needle probe to perform interstitial imaging deep below the tissue surface. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fiber encased within either a 22- or 23-gauge needle. 3D-OCT volumetric data sets were acquired by rotating and retracting the probe during imaging. We present the first published image of a human breast cancer tumor margin ...

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    23. A forward-imaging needle-type OCT probe for image guided stereotactic procedures

      A forward-imaging needle-type OCT probe for image guided stereotactic procedures
      A forward-imaging needle-type optical coherence tomography (OCT) probe with Doppler OCT (DOCT) capability has the potential to solve critical challenges in interventional procedures. A case in point is stereotactic neurosurgery where probes are advanced into the brain based on predetermined coordinates. Laceration of blood vessels in front of the advancing probe is an unavoidable complication with current methods. Moreover, cerebrospinal fluid (CSF) leakage during surgery can shift the brain rendering the predetermined coordinates unreliable. In order to address these challenges, we developed a forward-imaging OCT probe (740 μm O.D.) using a gradient-index (GRIN) rod lens that can provide real-time ...
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    24. Scanning and Tunable Micro-Optics for Endoscopic Optical Coherence Tomography

      Scanning and Tunable Micro-Optics for Endoscopic Optical Coherence Tomography
      The design, fabrication, and integration of micro-optical components for beam focus and steering are demonstrated in an endoscopic optical coherence tomography (OCT) system. The relevant components, a membrane-based microfluidic tunable microlens and an electrostatic 2-D scanning micromirror, are fabricated using silicon and polymer-based microelectromechanical system technologies. All components are assembled inside a 4.5 $muhbox{m}$ diameter probe. The design of the optical system, including substantiation of the need for focal length tunability, is presented, along with performance data of an OCT system using these components. A lateral resolution of about 13 $muhbox{m}$ is achieved, an improvement over fixed-focal ...
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    241-264 of 486 « 1 2 ... 8 9 10 11 12 13 14 ... 19 20 21 »
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