1. Articles in category: Probes

    1-24 of 596 1 2 3 4 ... 23 24 25 »
    1. Real-time Lissajous imaging with a low-voltage 2-axis MEMS scanner based on electrothermal actuation

      Real-time Lissajous imaging with a low-voltage 2-axis MEMS scanner based on electrothermal actuation

      Laser scanning based on Micro-Electro-Mechanical Systems (MEMS) scanners has become very attractive for biomedical endoscopic imaging, such as confocal microscopy or Optical Coherence Tomography (OCT). These scanners are required to be fast to achieve real-time image reconstruction while working at low actuation voltage to comply with medical standards. In this context, we report a 2-axis Micro-Electro-Mechanical Systems (MEMS) electrothermal micro-scannercapable of imaging large fields of view at high frame rates, e.g. from 10 to 80 frames per second. For this purpose, Lissajous scan parameters are chosen to provide the optimal image quality within the scanner capabilities and the sampling ...

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    2. NTU scientists develop handheld, high-resolution medical imaging device

      NTU scientists develop handheld, high-resolution medical imaging device

      NTU scientists develop handheld, high-resolution medical imaging device with potential for bedside scanning Scientists at Nanyang Technological University, Singapore (NTU Singapore) have developed the prototype of a handheld medical imaging device that can produce images down to resolutions of 1 to 2 micrometres. This is detailed enough to spot the first signs of tumours in specific cells and is about 100 times higher resolution than what X-Ray, computed tomography (CT) and Magnetic Resonance Imaging (MRI) machines can provide. The technology behind the device is a result of six years of optical imaging research and was jointly developed by a team ...

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    3. Optical coherence tomography system with dual optical coherence tomography probes

      Optical coherence tomography system with dual optical coherence tomography probes

      An optical coherence tomography (OCT) system with dual optical coherence tomography probes is provided comprising: an optical scope comprising a distal end; a first OCT probe; and, a second OCT probe, each of the first OCT probe and the second OCT probe mechanically attached to the optical scope, the first OCT probe and the second OCT probe being substantially paraxial and configured to focus on a same scanning area, the optical scope configured to optically image the same scanning area using the distal end, the first OCT probe having a higher resolution than the second OCT probe.

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    4. Side-viewing endoscopic imaging probe for swept source optical coherence tomography

      Side-viewing endoscopic imaging probe for swept source optical coherence tomography

      Endoscopic optical coherence tomography (OCT) has many promising applications in the fields of medical research and clinical diagnosis. In this letter, we present a side-viewing endoscopic OCT probe based on a gradient index (GRIN) lens with an air gap. By adjusting the length of the air gap the optical performance of the probe can be flexibly tuned. The quantitative relationships between the optical performance parameters of the probe and its structural parameters are theoretically analyzed by using the ABCD beam transfer matrix theory. The developed probe has a maximum diameter of 1.4 mm and a rigid length of 11 ...

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    5. Optical coherent imaging medical device

      Optical coherent imaging medical device

      An OCI medical device includes a coherent light source, a light sensor, a first processing unit adapted to calculate OCI Data from the light sensor, a control unit which allows taking or loading of at least one Reference OCI Value, a second processing unit adapted to calculate the Intra-Individual Relative Assessment of the OCI Data of an Imaging Zone and the at least one OCI Reference Value, and display means adapted to show at least one Relative OCI Value. Uses and a method for assessing the blood flow of a body region use OCI imaging and include an Intra-Individual Relative ...

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    6. Uniform focusing with an extended depth range and increased working distance for optical coherence tomography by an ultrathin monolith fiber probe

      Uniform focusing with an extended depth range and increased working distance for optical coherence tomography by an ultrathin monolith fiber probe

      It is difficult to maintain high transverse resolution over an increased depth range using miniature probes for optical coherence tomography (OCT) due to the rapid divergence of light and the space limitation. To solve this problem, we introduce a fiber-based filter in the proposed probe to manipulate its output beam. Significant mode interference (MI) is exploited to enhance the depth of focus (DOF), and the mode phase difference is tuned to achieve a uniform axial intensity within the DOF. The magnified MI field instead of the diffracted one is adopted as the final pupil filter in the probe to increase ...

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    7. Probe, optical coherence tomography device, and zero point correction method

      Probe, optical coherence tomography device, and zero point correction method

      A probe (1) is used in an optical coherence tomography device which irradiates measurement light to a subject and collects scattered light that has returned from the subject after being reflected. The probe (1) is provided with a scanning means (70) composed of galvanometer mirrors (72, 73) that change an irradiation direction of the measurement light. The scanning means (70) is provided with actuators (72b, 73b) which switch reflecting mirrors (72a, 73a) that reflect the measurement light between a state where the measurement light is reflected by the subject and returns as the scattered light, and a state where the ...

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    8. Steerable OCT catheter for real-time assistance during teleoperated endoscopic treatment of colorectal cancer

      Steerable OCT catheter for real-time assistance during teleoperated endoscopic treatment of colorectal cancer

      When detected early, colorectal cancer can be treated with minimally invasive flexible endoscopy. However, since only specialized experts can delineate margins and perform endoscopic resections of lesions, patients still often undergo colon resections. To better assist in the performance of surgical tasks, a robotized flexible interventional endoscope was previously developed, having two additional side channels for surgical instrument. We propose to enhance the imaging capabilities of this device by combining it with optical coherence tomography (OCT). For this purpose, we have developed a new steerable OCT instrument with an outer diameter of 3.5 mm. The steerable instrument is terminated ...

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    9. Balloon atherectomy catheters with imaging

      Balloon atherectomy catheters with imaging

      An atherectomy catheter includes an elongate flexible catheter body, a cutter near the distal end of the catheter body, a drive shaft connected to the cutter and extending within the catheter body, an imaging element near the distal end of the catheter body and an imaging shaft connected to the imaging element and extending within the catheter body. The cutter and the imaging element are mechanically isolated, and the drive shaft is configured to be axially translated relative to the imaging shaft and the catheter body.

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    10. Optical rotary junction incorporating a hollow shaft DC motor for high-speed catheter-based optical coherence tomography

      Optical rotary junction incorporating a hollow shaft DC motor for high-speed catheter-based optical coherence tomography

      In intravascular optical coherence tomography (OCT), the optical rotary junction plays an important role in rotating and pulling back the catheter to generate cross-sectional coronary artery images. To meet the requirements of high-speed intravascular OCT in a clinical setting, the rotary junction should generate high torque and low vibration. In this Letter, we demonstrate an ultrahigh speed optical rotary junction incorporating a hollow shaft brushless DC servomotor to remove a pulley belt, or a gear to minimize vibration noise and transfer stable torque. To evaluate the performance of the rotary junction, the vibration noise and variation of rotation were measured ...

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    11. Multichannel optical receivers

      Multichannel optical receivers

      Methods and apparatus are presented for multichannel optical coherence tomography. Light from a wavelength tuneable or steppable optical source is separated into one or more sample beams and one or more reference beams, and the one or more sample beams directed onto a sample to form one or more interaction regions. A plurality of returning probe beams are collected and mixed with the one or more reference beams to form an interference pattern comprising a plurality of interferograms having at least two distinct carrier frequencies. The multichannel optical apparatus can be provided with polarisation discrimination by mixing the returning probe ...

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      Mentions: Cylite
    12. Etching-enabled extreme miniaturization of graded-index fiber-based optical coherence tomography probes

      Etching-enabled extreme miniaturization of graded-index fiber-based optical coherence tomography probes

      We introduced and validated a method to miniaturize graded-index (GRIN) fiber-based optical coherence tomography (OCT) probes down to 70  μm in diameter. The probes consist in an assembly of single-mode (SM), coreless (CL), and graded-index (GRIN) fibers. We opted for a probe design enabling controlled size reduction by hydrogen fluoride etching. The fabrication approach prevents nonuniform etching for both the GRIN and SM fiber components, while it requires no probe polishing postetching. We found that the miniaturized probes present insignificant loss of sensitivity (∼1  dB) compared to their thicker (125  μm) counterparts. We also showed that their focusing capabilities remain ...

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    13. Apparatus and method for generating 3-D data for an anatomical target using optical fiber shape sensing

      Apparatus and method for generating 3-D data for an anatomical target using optical fiber shape sensing

      A fiber housing includes multiple shape sensing cores and a single optical core. A distal end of the fiber housing is positionable to direct the single optical core to a current point of an anatomical target. Collimated light over a first range of frequencies is projected from the single optical core to the current point. OFDR is used to detect reflected light scattered from the current point and to process the detected light to determine a distance to the current point. Light over a second range of frequencies is projected through the multiple shape sensing optical cores to the distal ...

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    14. Packaged Negative Axicon Optical Fiber Probe and Bessel Beam Interferometry for Refractive Index Measurement of Hazardous Liquid Sample

      Packaged Negative Axicon Optical Fiber Probe and Bessel Beam Interferometry for Refractive Index Measurement of Hazardous Liquid Sample

      In this work, we demonstrate the packaging of an optical fiber negative axicon probe generating Bessel beam and its application in the measurement of refractive index (RI) of hazardous liquids. The negative axicon probe is placed inside cascaded capillary tube capped with a glass coverslip of RI ~1.52 and thickness ~0.15 mm. The packaged probe, connected to a broadband source through an optical circulator, is dipped in different hazardous liquid samples. The reflected light from the air-glass as well as the glass-liquid interface couples to the negative axicon probe and interferes with the reference beam generated at the ...

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    15. Submillimeter diameter rotary-pullback fiber-optic endoscope for narrowband red-green-blue reflectance, optical coherence tomography, and autofluorescence in vivo imaging

      Submillimeter diameter rotary-pullback fiber-optic endoscope for narrowband red-green-blue reflectance, optical coherence tomography, and autofluorescence in vivo imaging

      A fiber-based endoscopic imaging system combining narrowband red-green-blue (RGB) reflectance with optical coherence tomography (OCT) and autofluorescence imaging (AFI) has been developed. The system uses a submillimeter diameter rotary-pullback double-clad fiber imaging catheter for sample illumination and detection. The imaging capabilities of each modality are presented and demonstrated with images of a multicolored card, fingerprints, and tongue mucosa. Broadband imaging, which was done to compare with narrowband sources, revealed better contrast but worse color consistency compared with narrowband RGB reflectance. The measured resolution of the endoscopic system is 25  μm in both the rotary direction and the pullback direction. OCT ...

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    16. Low cost scalable monolithic common path probe design for the application in endoscopic optical coherence tomography

      Low cost scalable monolithic common path probe design for the application in endoscopic optical coherence tomography

      Endoscopic optical coherence tomography is an interference based imaging technique which due to its micron level resolution ability found several applications in medical diagnostics. However, the standard image performance suffers from artefacts caused by dispersion imbalance and polarisation mismatches between reference and sample arm. Such artefacts can be minimised with the use of a special class of probes called common path probes where the reference surface is placed in the vicinity of the sample. Previously reported common path probes suffered from a compromise between sensitivity and resolution. In most cases, proposed probes were not scalable for industrial applications and required ...

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    17. Metasurface-based focus-tunable mirror

      Metasurface-based focus-tunable mirror

      Varifocal mirrors, which have various applications in optical coherent tomography and three-dimensional displays, are traditionally based on the fluid pressure or mechanical pusher to deform the mirror. The limitations of conventional varifocal mirrors are obvious, such as the heavy size of the device and constraints of tunability, due to their mechanical pressure control elements. The reprogrammable metasurface, a new flat photonic device with multifunction in an ultrathin dimension, paves the way towards an ultrathin and lightweight mirror with precise phase profile. Here, an active reconfigurable metasurface is proposed to achieve the manipulation of the wavefront. The meta-atom in the metasurface ...

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    18. Precision Microfabrication of Optical Probes for Intravascular Diagnostics (Thesis)

      Precision Microfabrication of Optical Probes for Intravascular Diagnostics (Thesis)

      This thesis details a collection of design, optimisation, fabrication and characterisation work to form fiber-optic probes and optical phantom devices for intravascular diagnostics in minimally invasive surgery (MIS). Optically generated ultrasound is an emerging technique to create broadband high frequency ultrasound via the photoacoustic effect. In the first segment of this thesis, the development of a novel miniature fiber-optic ultrasound transmitter is detailed. A morphologically controlled coating was formed at the endface of a multimode optical fiber by controlled electrospinning of a carbon-nanotube composite. Efficient optical ultrasound generation was realised, with signal amplitude, bandwidth and device form factor suited to ...

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    19. Comparison of optical coherence tomography angiography and narrow-band imaging using a bimodal endoscope

      Comparison of optical coherence tomography angiography and narrow-band imaging using a bimodal endoscope

      We present coregistered images of tissue vasculature that allow a direct comparison between the performance of narrow-band imaging (NBI) and optical coherence tomography angiography (OCTA). Images were generated with a bimodal endomicroscope having a size of 15  ×  2.4  ×  3.3  mm 3   (   l   ,   w   ,   h   )   that combines two imaging channels. The white light imaging channel was used to perform NBI, the current gold standard for endoscopic visualization of vessels. The second channel allowed the simultaneous acquisition of optical coherence tomography (OCT) and OCTA images, enabling a three-dimensional (3-D) visualization of morphological as well as functional tissue information. In order ...

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    20. Optical probe using multimode optical waveguide and proximal processing

      Optical probe using multimode optical waveguide and proximal processing

      An optical probe includes an optical source that generates an optical beam that propagates from a proximal end to a distal end of an optical fiber that imparts a transformation of a spatial profile of the optical beam. An optical control device imparts a compensating spatial profile on the optical beam that at least partially compensates for the transformation of the spatial profile of the optical beam imparted by the optical fiber in response to a control signal from a signal processor. A distal optical source generates a calibration light that propagates through the one or more optical waveguides from ...

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      Mentions: Eric A. Swanson
    21. Optical Fabrication: Glassblowing technique creates arrays of axicon lenses

      Optical Fabrication: Glassblowing technique creates arrays of axicon lenses

      Axicon lenses , which are conical in shape, are widely used to create so-called nondiffracting Bessel beams , which form a long, line-shaped focal region rather than the usual point focus. The line focus is useful for alignment, microfabrication, and other applications due to its insensitivity to axial motion, but cones are much more difficult than spheres to create in glass. Traditional optical techniques, such as grinding and polishing, or other approaches, such as femtosecond-laser ablation followed by polishing with a CO 2 laser, can be used, but are complex and not suited to large-volume production. Researchers at the FEMTO-ST Institute (Besan ...

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    22. Optical Coherence Tomography/Fluorescence Imaging: Fiber assembly enables efficient multimodal endoscopy

      Optical Coherence Tomography/Fluorescence Imaging: Fiber assembly enables efficient multimodal endoscopy

      While optical coherence tomography (OCT) provides structural contrast with a resolution on the order of tens of microns, for some applications this information is, in some contexts, insufficient to provide a definitive diagnostic. To mitigate this limitation, OCT has been used in conjunction with fluorescence imaging or spectroscopy for detection of molecular content in tissues. The combination of OCT and fluorescence has been used for a variety of applications, most notably to study atherosclerotic plaque in cardiology, 1 to visualize the fine vascular network in pulmonology (for which autofluorescence is used), 2 and for cancer imaging. 3

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    23. Micrometer size multi-functional probe for OCT and electro-physiological recording

      Micrometer size multi-functional probe for OCT and electro-physiological recording

      A device and method for guided insertion of microelectrodes into tissue is provided. The device includes a flexible optical fiber for optical coherence tomography imaging, a metal layer coating the optical fiber for recording electrical signals and an outer insulation layer coating the metal layer along the optical fiber length. The method includes inserting an optical fiber coated with a metal layer and further coated with an insulation layer into a tissue, collecting intraoperative image data through the optical fiber by optical coherence tomography, receiving the image data on a computer and displaying the image on a monitor, using the ...

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    24. Polarization-sensitive optical coherence tomography with a conical beam scan for the investigation of birefringence and collagen alignment in the human cervix

      Polarization-sensitive optical coherence tomography with a conical beam scan for the investigation of birefringence and collagen alignment in the human cervix

      By measuring the phase retardance of a cervical extracellular matrix, our in-house polarization-sensitive optical coherence tomography (PS-OCT) was shown to be capable of (1) mapping the distribution of collagen fibers in the non-gravid cervix, (2) accurately determining birefringence, and (3) measuring the distinctive depolarization of the cervical tissue. A conical beam scan strategy was also employed to explore the 3D orientation of the collagen fibers in the cervix by interrogating the samples with an incident light at 45° and successive azimuthal rotations of 0-360°. Our results confirmed previous observations by X-ray diffraction, suggesting that in the non-gravid human cervix collagen ...

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