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Results for “Fiber Optic Technology”

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At least 91 records · Page 5Linked to original sources
PubMed2005

Passive mode-locking by use of waveguide arrays.

A novel mode-locking technique is presented in which the intensity-dependent spatial coupling dynamics of a waveguide array is used to achieve temporal mode-locking in a passive optical fiber laser. By use of the discrete, nearest-neighbor spatial coupling of the waveguide array, low-intensity light can be transferred to the neighboring waveguides and ejected (attenuated) from the laser cavity. In contrast, higher-intensity light is self-focused in the waveguide and remains largely unaffected. Numerical studies of this pulse shaping mechanism (intensity discrimination) show that using current waveguide arrays and standard optical fiber technology produces stable and robust mode-locked soliton-like pulses.

Journal Article↗
PubMed2005

Standard reference material 2036 near-infrared reflection wavelength standard.

Standard Reference Material 2036 (SRM 2036) is a certified transfer standard intended for the verification and calibration of the wavelength/wavenumber scale of near-infrared (NIR) spectrometers operating in diffuse or trans-reflectance mode. SRM 2036 Near-Infrared Wavelength/Wavenumber Reflection Standard is a combination of a rare earth oxide glass of a composition similar to that of SRM 2035 Near-Infrared Transmission Wavelength/Wavenumber Standard and SRM 2065 Ultraviolet-Visible-Near-Infrared Transmission Wavelength/Wavenumber Standard, but is in physical contact with a piece of sintered poly(tetrafluoroethylene) (PTFE). The combination of glass contacted with a nearly ideal diffusely reflecting backing provides reflection-absorption bands that range from 15% R to 40% R. SRM 2036 is certified for the 10% band fraction air wavelength centroid location, (10%)B, of seven bands spanning the spectral region from 975 nm to 1946 nm. It is also certified for the vacuum wavenumber (10%)B of the same seven bands in the spectral region from 10 300 cm(-1) to 5130 cm(-1) at 8 cm(-1) resolution. Informational values are provided for the locations of thirteen additional bands from 334 nm to 804 nm.

Fiber Optic Technology↗
PubMedDate not supplied

A shear and plantar pressure sensor based on fiber-optic bend loss.

Lower-limb complications associated with diabetes include the development of plantar ulcers that can lead to infection and subsequent amputation. While we know from force-plate analyses that medial/lateral and anterior/posterior shear components of ground-reaction forces exist, little is known about the actual distribution of these stresses during daily activities or about the role that shear stresses play in causing plantar ulceration. Furthermore, one critical reason why these data have not been obtained previously is the lack of a validated, widely used, commercially available shear sensor, partly because of the various technical issues associated with measuring shear. In this study, we present a novel means of transducing plantar pressure and shear stress with a fiber-optic sensor. The pressure/shear sensor consists of an array of optical fibers lying in perpendicular rows and columns separated by elastomeric pads. We constructed a map of normal and shear stresses based on observed macrobending through the intensity attenuation from the physical deformation of two adjacent perpendicular fibers. Initial results show that this sensor exhibits low noise and responds to applied normal and shear loads with good repeatability.

Biomechanical Phenomena↗
PubMed1999

Evaluation of porcine fat with fiber-optic spectroscopy.

Spectroscopy using four types of fiberoptic probes and a sensor at wavelengths of 400 to 1,100 nm was evaluated to assess porcine fat quality. The shapes of the spectrum for the leaf fat with white color and various firmnesses differed with the type of probe: surface, contact, insertion, or transmittance. The internal reflectance ratio using the insertion probe at wavelengths from approximately 600 to 1,000 nm was positively correlated with the hardness, melting point, and saturated fatty acid content of the fat, but it was negatively correlated with the refractive index and polyunsaturated fatty acid content. The correlations between the internal reflectance ratio using the insertion probe and the monounsaturated fatty acid content were strong only near 1,100 nm. Surface reflectance at more than 650 nm was negatively correlated with refractive index. Transmittance at almost all wavelengths showed positive correlations with monounsaturated fatty acid content, but it was negatively correlated with hardness, melting point, and saturated fatty acid content. The interactance using the contact probe did not have a significant correlation with any physiochemical characteristics. The strongest relationships for hardness, refractive index, saturated fatty acid content, monounsaturated fatty acid content, polyunsaturated fatty acid content, and melting point were obtained at 650 nm (r = .88), 660 nm (r = -.91), 645 nm (r = .73), 1,095 nm (r = .68), and 930 nm (r = -.76), respectively, using the insertion probe and 1,050 nm (r = -.79) using the transmittance probe (P<.05). These results indicated that fiber-optic methods were rapid and useful techniques for the evaluation of porcine fat quality.

Adipose Tissue↗
PubMed1998

Applications of fiber-optic evanescent wave spectroscopy.

The evanescent wave (EW) component of light propagated via fiber-optic wave-guides can be used to both sense and transmit information regarding the immediate environment of the fiber's surface. In this article, an outline of the theoretical and practical aspects of this emerging methodology is given, as well as a discussion of the advantages, disadvantages, and limitations of the technique. Examples are given of how EW spectroscopy may be used in the analysis of pharmaceutical systems. Evaluation of attributes of components of EW spectroscopy allows prediction of the future for this rapidly evolving area of photonics.

Biosensing Techniques↗
PubMed1997

Information at the speed of light.

Once cutting edge, fiber optic cable is now the backbone of choice for health care organizations with growing networks. The question today is not whether to use fiber, but how much and where.

Computer Communication Networks↗
PubMedDate not supplied

Fiberoptic bronchoscopy. Indications, training, and certification.

To assist hospital committees in maintaining high standards of practice in their facilities, the American College of Physicians has prepared a list of cognitive and procedural objectives which may serve as guidelines in evaluating physicians' performance of fiber-optic bronchoscopy. These are outlined here, along with indications, contraindications, and high-risk situations.

Bronchoscopy↗
PubMed1976

Fiber optic surgical retractor.

A ramus retractor with a variable high-intensity light source has been designed. It offers access, direct high-intensity visibility, reliability, compactness, and sterilizability. We have used this modification for the past five years. It has allowed direct visibility and identification of structures in the surgical field without the use of cumbersome overhead surgical lights, headlights, or spotlights.

Fiber Optic Technology↗
PubMed2001

Evolution of dental ceramics.

A porcelain system has been developed that combines dental-ceramic engineering and fiber-optic technology. This system involves cutting-edge technology that results in optical properties that emulate nature closer than ever before. The enhanced opalescence and fluorescence, combined with optical clarity, results in color-reactive porcelain that looks natural and esthetic in any light, and reacts to light in the same manner as the natural dentition.

Ceramics↗
PubMed2004

[Optical diagnosis of cervical dysplasia].

Cervix cancer is a curable disease when diagnosed at an early stage. Screening of cervical lesions by cytology and colposcopy with in situ staining has allowed for substantial progress in early diagnosis and consequently the cure of cervix cancer. Nevertheless, because of its low specificity, this approach generally implies repetitive tissue sampling and, thus a relative long time before the treatment of the lesions. Furthermore, the cost of preparation and analysis of biopsy samples is sufficiently high to represent a burden for industrialized countries and a virtual impossibility for the developing world. To overcome these problems, various biophotonic methods using optical fibers have been developed to allow for detection of cervical epithelial anomalies in a specific, fast and non-invasive way. This process, known as "optical biopsy", is based on the measurement of light-tissue interactions, which are analysed by various mathematical and data processing methods, to provide information on the metabolism and morphology of epithelial tissue. Currently investigated methods can be distinguished according to the type of signal used to probe the tissue (fluorescence, reflectance), the depth of analysed tissue (surface analysis, confocal imaging, tomography), the analysis modalities (spectral measurements or imaging), and the use of additive molecules (contrasting or photosensitizing agents, inorganic fluorophores). While most of the methods remain experimental, constant progress in the understanding of the mechanisms of light behavior in biological environments as well as advances in optical fibers technology, will make a number of these methods soon available for clinical practice to contribute efficiently to the reduction of biopsy number and cost of cervical screening.

Contrast Media↗
PubMed2005

[Teleradiology using uncompressed DICOM format via exclusive fiber-optic system].

We developed a system for teleradiology using exclusive fiber optics for transferring images formatted in uncompressed DICOM. This system was built up with commercially available machines and software provided from various companies. We are now operating the system with five remote hospitals and have had one year of experience. The current system took advantage of the security and transfer efficiency of exclusive fiber optics. Uncompressed DICOM images were useful for the identification of cases and user-friendly for viewing. The reading room is located in our university hospital, and the location is convenient for consultation and discussion of cases.

Fiber Optic Technology↗
PubMed2004

[Investigations of transient time-dependent spectral multi-channel measurement for shocked KCl crystal].

In this paper, the authors reported a new method for measuring transient time-dependent spectra using multi-fiber delay coupler and optical multi-channel analysis technique. The fiber delay coupler consists of five fibers with different lengths and its time-delay between two fibers is determined by the different fiber lengths. The light beams that came from the fiber coupler were coupled by a lens system into the slit of a spectrograph and formed a spectral pattern on the focus plane of the spectrometer. A two-dimensional CCD detector converted the optical pattern into an electrical pattern, and then the transient time-dependent spectra were obtained by a personal computer. The experimental setup was constructed, and the transient time-dependent spectra were measured for KCl crystal shocked by a high speed pill. The time resolution was 20 ns, and the spectral intensity resolution reached 1/18 bit.

Crystallins↗