Technical Glossary Absorption In optics, the loss or attenuation that is due to material properties of an optical fiber. Absorption is quite often wavelength dependent.
Cable, fiber optic A package or assembly for an optical fiber or bundle of fibers that may include buffering, strength members and/or an outer jacket.
Acceptance angle The maximum cone half-angle for which incident light is captured by and will travel through the optical fiber. If the acceptance angle is θ then the acceptance cone is defined by a solid cone of 2θ. See NA for more details.
Capillary Electrophoresis (CE) Capillary Electrophoresis is a separation method based on the differential electrophoretic migration rate of sample components in a capillary when a voltage is applied. The detection method is usually “on-column” using UV spectrometric or fluorescence analysis through a window in the capillary. Performing electrophoresis in small-diameter capillaries allows the use of very high electric fields because the small capillaries efficiently dissipate the heat that is produced. Increasing the electric fields produces very efficient separations and reduces separation times. CE detection includes absorbance, fluorescence, electrochemical, and mass spectrometry.
Acrylate A polymer material used in optical fibers as a buffer coating or cladding or in capillary as a coating. Adsorption In chemistry, the taking up by the surface of a solid or liquid (adsorbent) of the atoms, ions, or molecules of a gas or other liquid (adsorbate). Porous or finely divided solids can hold more adsorbate because of the relatively large surface area exposed. Attenuation The amount of light loss experienced in an optical fiber or optical media as a function of length. For optical fiber it is usually expressed in dB (decibels) per kilometer (km). See Tr a n s m i s s i o n. Bandwidth The range of frequencies (or wavelengths) which is useful for a device or system. In optical fiber, it is a measure of information carrying capacity. The frequency bandwidth is usually described as the frequency where the signal power is one-half the power at zero frequency. The wavelength bandwidth is usually expressed in terms of spectral wavelength-dependent attenuation or transmission, and is not necessarily related to the signal bandwidth. Bending loss Loss in an optical fiber caused by bending of the fiber. This loss is usually due to internal light paths exceeding the critical angle for TIR. Both micro-bending and macro-bending are loss mechanisms in optical fibers. Bend Radius The radius of a drum or mandrel around which an optical fiber or cable is wrapped or wound. The radius at the center of the fiber or cable is the bend radius plus one-half the fiber or cable diameter. Broad Spectrum fiber An optical fiber that has a relatively wide transmission spectrum window ranging from ~300nm to ~2µm. B u ff e r The buffer is an outer coating on an optical fiber. Typically a plastic material, it protects the fiber from external stresses and abrasion.
Capillary t u b i n g Quartz or glass tubing which has internal diameters from less than 2µm to more than 2000µm. The outside diameter can range from 90µm to greater than 3500µm, depending on the application requirements. An outside buffer coating of polyimide, silicone, acrylate or fluoropolymers can be added. Chromatic dispersion The separation of a beam into its various wavelength components. In an optical fiber, dispersion occurs because of the differing wavelengths propagating at different speeds. This causes pulse spreading or broadening. See D i s p e r s i o n. Chromatography In chemistry, analytical technique used for the chemical separation of mixtures and substances. The technique depends on the differential distribution of solutes between the mobile and stationary phases. Cladding A low refractive index optical material that surrounds the core of an optical fiber. It is used to cause reflection of the core light while preventing scattering from surface contact. In all-glass fibers, the cladding is glass. In plastic-clad Silica fibers, the plastic cladding also may serve as the buffer coating.1 In some applications, multiple cladding layers can be used. Color The attribute of visual perception that can be described as having characteristics of hue, saturation, and brightness. It does not include aspects of extent (e.g., size, shape, texture, etc.) and duration (e.g., movement, flicker, etc.). A color that is seen can be a single wavelength or a combination of wavelengths. Most colors are a very complex combinations of many wavelengths of various amplitudes. Core The light-guiding portion of an optical fiber having a higher refractive index than the cladding. It is usually made of a pure synthetic Silica material, but can be a doped material to provide special fiber characteristics.
The Photonics DictionaryTM, 43rd Edition, 1997, Laurin Publishing Co., Inc., Pittsfield, MA
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