Abstract: Polymer nanocomposite having: a) a polylactic polymer; and b) a modified phyllosilicate composition having a modifying agent which includes hexadecyl trimethyl ammonium cations which are intercalated between the layers of the phyllosilicate; and preparation process of such a polymer nanocomposite. The polymer nanocomposite is particularly useful for packaging, particularly food and drink packaging.

Abstract: A communication line such as an optical fiber or cable is attached along a wall, ceiling, trim piece, or other selected surface on or inside of a building, by paying out the fiber from an applicator tool while the tool guides the fiber along the selected surface. The outer surface of the fiber is prepared so that the fiber will be in a temporarily tacky condition when the fiber is pressed onto the selected surface by the applicator tool. The fiber is pre-coated with an adhesive that is activated by a fluid supplied by the applicator tool. As the applicator tool presses the fiber onto the selected surface, the activated adhesive coating on the fiber quickly becomes non-tacky to attach the fiber firmly to the surface.

Abstract: Cables having non-stripping, or buffer-free, optical fibers are disclosed. The cables each have a buffer-free optical fiber including a core, cladding layer and a thin protective coating enclosing the cladding and having an overall diameter of 125 ?m. This protective coating protects the cladding and core from moisture and provides structural integrity to prevent physical damage to the fiber during installation and termination with connectors. Embodiments of this non-stripping fiber do not require removal of a buffer layer during field termination so connections can be formed using simple cleaving techniques. As such, the field termination process for embodiments is simplified compared with conventional approaches.

Abstract: A coated glass fiber 1 comprising a glass fiber 10 and a resin coating layer containing an inner layer 20 and an outer layer 30 provided on the outer circumference of the glass fiber 10, wherein the resin constituting the inner layer 20 is formed by curing a urethane-based ultraviolet curable resin composition containing a surfactant in an amount of 0.1 to 1.0% by weight and Young's modulus thereof is from 0.3 to 10 MPa. The coated optical fiber has a good water immersion resistance.

Abstract: A monomeric formulation for fabrication of microlattice structures, the monomeric formulation including a plurality of monomers, a first photoinitiator configured to substantially activate above a wavelength of light, and a second photoinitiator configured not to substantially activate above the wavelength of light and to substantially activate below the wavelength of light.

Abstract: Provided is a plastic optical fiber cable including a plastic optical fiber 12 comprising of a core 11A and a cladding 11B, and a jacketing layer covering the plastic optical fiber 12, in which the jacketing layer includes at least two layers of an inner layer 13 and an outer layer 14, the inner layer 13 is formed of a resin comprising of a copolymer of ethylene and a (meth)acrylic compound, and the outer layer 14 is formed of a fluorine-based resin. A plastic optical fiber cable excellent in flame retardance, appearance, and processability at the time of use is obtained from the plastic optical fiber cable described above.

Abstract: An optical fiber includes a core, a cladding, and a thermally conductive member. The cladding is formed in a surrounding of the core. The thermally conductive member is formed in a surrounding of the cladding and includes a thermal conductivity higher than thermal conductivities of the core and the cladding.

Abstract: Provided is a coated optical fiber excellent in both characteristics of the microbending loss resistance and the low-temperature characteristic. The coated optical fiber 1 comprises an optical fiber 10 that has a cladding layer composed of glass formed on an outer periphery of a glass core, a primary coating layer 20 that coats an outer periphery of the optical fiber 10, and a secondary coating layer 30 that coats an outer periphery of the primary coating layer 20, wherein the primary coating layer 20 has a Young's modulus of 1.2 MPa or less, the secondary coating layer 30 has a Young's modulus of 700 MPa or more, and the primary coating layer 20 contains tin in a content of 70 ppm or less.

Abstract: An optical active fiber is configured with an asymmetrically-shaped core having at least one long axis and a shortest axis which extends transversely to the long axis. The outmost cladding of the active fiber is configured with a marking indicating the orientation of the short axis. The marking allows for bending the fiber so that the shortest axis extends along and lies in the plane of the bend thereby minimizing distortion of a mode which is guided by the asymmetrically-shaped core as light propagates along the bend.

Abstract: A chemical sensor is provided. The sensor includes at least one lightguiding element having an optical core. The lightguiding element comprises a layer of graphene situated in sufficient proximity to the core to exhibit evanescent wave absorption of optical energy in at least one optical mode guided in the core.

Abstract: A radiation-resistant optical fiber includes at least one core and at least one first cladding surrounding the core. The core includes a phosphosilicate matrix, the core being rare-earth doped, the rare earth being chosen from erbium, ytterbium, neodymium, thulium or erbium-ytterbium of thulium-holmium codoped and the core is cerium codoped. Also described is a method for radiation-hardening an optical fiber including the core having a phosphosilicate matrix, the core being rare-earth doped, the rare earth being chosen from erbium, ytterbium, neodymium and thulium, or erbium-ytterbium or thulium-holmium codoped, and including a step of cerium codoping the core of the fiber.

Abstract: In one embodiment, a chalcogenide glass optical fiber is produced by forming a billet including a chalcogenide glass mass and a polymer mass in a stacked configuration, heating the billet to a temperature below the melting point of the chalcogenide glass, extruding the billet in the ambient environment to form a preform rod having a chalcogenide glass core and a polymer jacket, and drawing the preform rod.

Abstract: An inexpensive low-attenuation optical fiber 1 suitable for use as an optical transmission line in an optical access network is a silica based glass optical fiber and includes a core 11 including the center axis, an optical cladding 12 surrounding the core, and a jacket 13 surrounding the optical cladding. The core contains GeO2 and has a relative refractive index difference ?core, based on the optical cladding, greater than or equal to 0.35% and less than or equal to 0.50% and has a refractive index volume v greater than or equal to 0.045 ?m2 and less than or equal to 0.095 ?m2. The jacket has a relative refractive index difference ?J greater than or equal to 0.03% and less than or equal to 0.20%. Glass constituting the core has a fictive temperature higher than or equal to 1400° C. and lower than or equal to 1590° C. Residual stress in the core is compressive stress that has an absolute value greater than or equal to 5 MPa.

Abstract: The present invention relates to an optical fiber and an optical cable which can be used for a long term even under environments in which an oil content migrates into them, and the optical fiber has a glass fiber extending along a predetermined axis, and a coating. The coating is composed of a plurality of layers each of which is comprised of an ultraviolet curable resin or a thermosetting resin, and swelling rates of the respective coating layers are set so that they increase from an outer peripheral surface of the glass fiber to an outer peripheral surface of the cable jacket.

Abstract: A multimode optical fiber includes: (i) a graded index glass core having a radius R1 in the range of 20 microns to 50 microns, a maximum relative refractive index ?1MAX in the range between 0.5% and 3%; a graded index having a profile with (a) by an alpha (?) parameter wherein 1.9???2.2, and (b) a deviation from the alpha profile in at least one region of the core, such that the difference in the refractive index delta of the core from that determined by the core alpha value, at the radius R1 is less than 0.001, and (ii) a cladding surrounding and in contact with the core, wherein the fiber has an bandwidth greater than 5000 MHz-km at a wavelength ? where ??800 nm.

Abstract: An optical fiber includes: a core including a photosensitive material disposed therein, the core having a first index of refraction; a depressed cladding surrounding the core and having a second index of refraction that is lower than the first index of refraction; and an outer cladding surrounding the depressed cladding and having a third index of refraction that is higher than the depressed cladding.

Abstract: A new radiation curable Secondary Coating for optical fibers is described and claimed wherein said composition comprises a Secondary Coating Oligomer Blend, which is mixed with a first diluent monomer; a second diluent monomer; optionally, a third diluent monomer; an antioxidant; a first photoinitiator; a second photoinitiator; and optionally a slip additive or a blend of slip additives; wherein said Secondary Coating Oligomer Blend comprises: ?) an Omega Oligomer; and ?) an Upsilon Oligomer; wherein said Omega Oligomer is synthesized by the reaction of ?1) a hydroxyl-containing (meth)acrylate; ?2) an isocyanate; ?3) a polyether polyol; and ?4) tripropylene glycol; in the presence of ?5) a polymerization inhibitor; and ?6) a catalyst; to yield the Omega Oligomer; wherein said catalyst is selected from the group consisting of dibutyl tin dilaurate; metal carboxylates, including, but not limited to: organobismuth catalysts such as bismuth neodecanoate; zinc neodecanoate; zirconium neodecanoate; zinc 2-ethylh

Abstract: Methods for producing a semifinished part for the manufacture of an optical fiber are disclosed. The methods are optimized in terms of bending. The methods include the steps of providing a shell tube with a shell refractive index which is lower in relation to the light-conducting core. Then, at least one protective, intermediate and/or barrier layer is applied to a radially outermost and/or innermost tube surface of the respective shell tube, wherein a build-up of light-conducting layers is realized on the inner side and/or the outer side of the shell tube. Finally, the shell tubes are joined by collapsing so as to form the semifinished part.

Abstract: A breakout cable includes a polymer jacket and a plurality of micromodules enclosed within the jacket. Each micromodule has a plurality of bend resistant optical fibers and a polymer sheath comprising PVC surrounding the bend resistant optical fibers. Each of the plurality of bend resistant optical fibers is a multimode optical fiber including a glass cladding region surrounding and directly adjacent to a glass core region. The core region is a graded-index glass core region, where the refractive index of the core region has a profile having a parabolic or substantially curved shape. The cladding includes a first annular portion having a lesser refractive index relative to a second annular portion of the cladding. The first annular portion is interior to the second annular portion. The cladding is surrounded by a low modulus primary coating and a high modulus secondary coating.

Abstract: The present invention relates to an optical fiber and an optical cable which can be used for a long term even under environments in which an oil content migrates into them, and the optical fiber has a glass fiber extending along a predetermined axis, and a coating. The coating is composed of a plurality of layers each of which is comprised of an ultraviolet curable resin or a thermosetting resin, and swelling rates of the respective coating layers are set so that they increase from an outer peripheral surface of the glass fiber to an outer peripheral surface of the cable jacket.

Abstract: An optical fiber core having a primary layer and a secondary layer, which are laminated on a bare optical fiber. The primary layer is formed by curing an ultraviolet-curable resin composition containing a first silane coupling agent, which can be incorporated into a resin skeleton, and a second silane coupling agent, which cannot be incorporated into a resin skeleton. The first silane coupling agent contains a compound having a methoxy group, and the second silane coupling agent contains a compound having an ethoxy group.

Abstract: The present invention relates to an optical fiber and an optical cable which can be used for a long term even under environments in which an oil content migrates into them, and the optical fiber has a glass fiber extending along a predetermined axis, and a coating. The coating is composed of a plurality of layers each of which is comprised of an ultraviolet curable resin or a thermosetting resin, and swelling rates of the respective coating layers are set so that they increase from an outer peripheral surface of the glass fiber to an outer peripheral surface of the cable jacket.

Abstract: An optical fiber according to an embodiment of the present invention is provided with a center core, a side core, and a cladding. The center core includes a ring part where a relative index difference varies discontinuously, in its peripheral region, and when a is a radius from a core center to an outside of the ring part and c is a radius to a position where the relative index difference is maximum in the side core, an index profile is realized in a shape where c/a is in the range of 2.25 to 2.50, so as to enable setting of a dispersion value, a cable cutoff wavelength, a bending loss in the diameter of 20 mm, and an effective area in desired ranges.

Abstract: A low cost composition that cures rapidly and which is suitable for coating an optical fiber comprises at least one ethylenically unsaturated monomer; at least one photoinitiator; and at least one non-radiation-curable polar polymer having pendent groups that facilitate low energy chemical bonding, hydrogen bonding, dipolar interactions or other interactions with radical compounds formed during polymerization of the monomer. The non-radiation-curable polar polymer(s) are inexpensive and reduce and/or eliminate the need for expensive urethane acrylate oligomers, without sacrificing properties, and while achieving rapid cure speeds.

Abstract: Optical fibers having a mode field diameter at 1310 nm of at least 8.8 ?m, wire mesh covered drum microbending losses at 1550 nm less than 0.03 dB/km, and a 2 m cutoff wavelength less than 1320 nm. The fibers may include a central core region, an inner cladding region, an outer cladding region, a primary coating with an in situ modulus less than 0.20 MPa and glass transition temperature less than ?35° C., and a secondary coating with an in situ modulus greater than 1500 MPa. The fibers may further include a depressed index cladding region. The relative refractive index of the central core region may be greater than the relative refractive index of the outer cladding region may be greater than the relative refractive index of the inner cladding region. The fibers may be produced at draw speeds of 30 m/s or greater.

Abstract: Holey fibers provide optical propagation. In various embodiments, a large core holey fiber comprises a cladding region formed by large holes arranged in few layers. The number of layers or rows of holes about the large core can be used to coarse tune the leakage losses of the fundamental and higher modes of a signal, thereby allowing the non-fundamental modes to be substantially eliminated by leakage over a given length of fiber. Fine tuning of leakage losses can be performed by adjusting the hole dimension and/or spacing to yield a desired operation with a desired leakage loss of the fundamental mode. Resulting holey fibers have a large hole dimension and spacing, and thus a large core, when compared to traditional fibers and conventional fibers that propagate a single mode. Other loss mechanisms, such as bend loss and modal spacing can be utilized for selected modes of operation of holey fibers.

Abstract: Epoxy-functional polysiloxanes containing epoxy groups and hydrocarbyl groups free of aliphatic unsaturation, a silicone composition containing a polysiloxane selected from the aforementioned epoxy-functional polysiloxanes, a cured polysiloxane prepared by exposing the silicone composition to ultraviolet radiation, a coated optical fiber containing a cured polysiloxane, and a method of preparing a coated optical fiber.

Abstract: A colored optical fiber including a glass optical fiber; a primary coating layer that covers the glass optical fiber; a secondary coating layer that covers the primary coating layer; and a colored layer that coats the secondary coating layer. The relaxation modulus after 24 hours at 60° C. of of the layers coated is 140 MPa or less.

Abstract: A fiber having a large effective area at 1550 nm of at least 130 ?m2 and a wire mesh drum microbending loss of less than 0.4 dB/km at a wavelength of 1550 nm. The fibers may include a core, a cladding, and a coating. The core may include a central core region and a surrounding first core region. The cladding may include a depressed index inner cladding region and an outer cladding region. The coating may include a primary coating surrounding the cladding and a secondary coating surrounding the primary coating. The primary coating may be formed from a primary composition that may include an acrylate monomer or an N-vinyl amide monomer in combination with an acrylate oligomer, where the acrylate oligomer is present at 35 wt % to 55 wt %. The secondary coating may be formed from a secondary composition including one or more acrylate or diacrylate monomers and an acrylate or methacrylate oligomer, where the oligomer is present at 3 wt % or less.

Abstract: An optical fiber comprising: (I) a germania doped central core region having outer radius r1 and (II) a maximum relative refractive index ?1max and a cladding region including (i) a first inner cladding region having an outer radius r2>5 microns and refractive index ?2; (ii) a and a second inner cladding region having an outer radius r3>9 microns and comprising refractive index ?3; and (iii) an outer cladding region surrounding the inner cladding region and comprising refractive index ?4, wherein ?1max>?4, ?2>?3, and wherein 0.01%??4??3?0.09%, said fiber exhibits a 22 m cable cutoff less than or equal to 1260 nm, and 0.25?r1/r2?0.85.

Abstract: An optical fiber includes an interlocking microstructure formed on an outer periphery of the fiber that configures the fiber to be interlocked with another optical fiber including a complementary interlocking microstructure coating.

Abstract: An optical fiber comprising: (i) a core having a refractive index profile; (ii) an annular cladding surrounding the core; (iii) a primary coating contacting and surrounding the cladding, the primary coating having an in situ modulus of less than 0.35 MPa and an in situ glass transition temperature of less than ?35° C.; and (iv) a secondary coating surrounding the primary coating, the secondary coating having an in situ modulus of greater than 1200 MPa; wherein the refractive index profile of said core is constructed to provide an LP11 theoretical cutoff wavelength greater than 2.0 ?m and an effective area greater than 110 microns2 at 1550 nm.

Abstract: A radiation curable resin composition, containing (A) urethane oligomer containing the reactants of an aliphatic polyester or polyether diol and a diisocyanate and a monohydric alcohol, or urethane oligomer obtained by reacting the reactants of an aliphatic polyester or polyether diol and a diisocyanate with a monohydric alcohol and then reacting a hydroxyl group-containing (meth)acrylate, and (B) monofunctional acrylic monomer, and the contained quantity of (C) polyfunctional acrylic monomer is 2 mass % or less is described and claimed.

Abstract: An optical transmission fiber including a core having a first index of refraction, a cladding material located around the core and having a second index of refraction less than the first index of refraction, a first coating material located around a first portion of the cladding material and having a third index of refraction greater than the second index of refraction, and a second coating material located around a second portion of the cladding material and having a fourth index of refraction less than the second index of refraction.

Abstract: A wet-on-dry process for coating a glass optical fiber with a radiation curable Primary Coating, comprising (a) operating a glass drawing tower to produce a glass optical fiber; (b) applying a radiation curable Primary Coating composition onto the surface of the optical fiber; (c) applying radiation to effect curing of said radiation curable Primary Coating composition; (d) applying a secondary coating to the Primary Coating; and (e) applying radiation to effect curing of said secondary coating. Also, a wet-on-wet process for coating a glass optical fiber with a radiation curable Primary Coating, comprising (a) operating a glass drawing tower to produce a glass optical fiber; (b) applying a radiation curable Primary Coating composition onto the surface of the optical fiber; (c) applying a secondary coating to the Primary Coating; and (d) applying radiation to effect curing of the Primary Coating and the secondary coating.

Abstract: Provided is an optical fiber which is provided with heat resistance and productivity and in which a transmission loss is suppressed even in a high-temperature environment. It has, on an outer periphery of a glass fiber composed of a core part and a cladding part, a coating layer made by crosslinking an energy-curable resin composition containing a silicon compound, in which the silicon compound contained in the energy-curable resin composition of the coating layer as an outermost layer has a specified structure having a cyclic silicone site having an epoxy group and a linear silicone site, with the content of the cyclic silicone site in the compound being from 10 to 30% by mass.

Abstract: An optical fiber with a b-stageable hybrid adhesive coating includes an optical fiber and an outer jacket. The outer jacket includes at least one layer that includes a partially cured b-stageable hybrid adhesive.

Abstract: An optical fiber includes an optical waveguide, a first coating layer disposed to surround the optical waveguide and a second coating layer disposed to surround the first coating layer, wherein the first coating layer is formed by a cured polymeric material obtained by curing a radiation curable composition including at least one (meth)acrylate monomer esterified with at least one branched alcohol having from 9 to 12 carbon atoms, and the second coating layer is formed by a cured polymeric material obtained by curing a radiation curable (meth)acrylate composition including from 0.8% to 1.5% by weight of silica, based on the total weight of the composition.

Abstract: A method of manufacturing an optical fiber preform includes forming a porous body that is made of glass particles and includes a first region and a second region formed on an outer circumference of the first region, performing a first heat treatment on the porous body under an atmosphere containing a fluorine gas, performing a second heat treatment on the porous body after the first heat treatment at a higher temperature than that of the first heat treatment to form a transparent glass body, and forming a cladding portion on an outer circumference of the transparent glass body.

Abstract: A buffered optical fiber (10) comprises a central core (11) surrounded by an optical cladding (12), a coating (13) surrounding the optical cladding, a protective buffer (15) surrounding the coating and an intermediate layer (14) between the coating and the protective buffer. The intermediate layer consists of hot melt seal and peel material. The intermediate layer (14) may be extruded in tandem with the outer protective buffer (15).

Abstract: This invention discloses a bend insensitive single mode fiber, which is composed by a bare glass fiber with a round cross section and two resin protective layers with circular cross sections surrounding the outer of the bare glass fiber. It is characterized in that the bare glass fiber is composed by a core layer with a round cross section and two claddings with circular cross sections. The refractive index of the core layer is higher than the index of the two claddings and the refractive index difference between the core layer and the first cladding is larger than the difference between the first and second claddings. The second cladding is made of pure SiO2. The refractive index profile of the core layer follows a power function, and the refractive index profile of the two claddings follow a ladder-type distribution. The loss of the invented fiber is insensitive to the bending of the fiber, which meets the requirements of ITU.T G.657.A and G.657.B standards, respectively.

Abstract: A method of manufacturing an optical fiber includes a first step of drawing an optical fiber preform into a glass fiber and disposing a fiber coating on the outer circumference of the glass fiber to form a parent optical fiber; a second step of cutting the parent optical fiber into a plurality of individual optical fibers; a third step of determining, at, at least, one spot of the parent optical fiber, a failure strength F1 and a failure time T; a fourth step of determining a failure strength F2 of each of the individual optical fibers; and a fifth step of selecting an optical fiber having a failure strength F2 of 5.5 kgf or more from the individual optical fibers cut from the parent optical fiber whose failure strength F1 and failure time T satisfy the inequality T>2.6×10?11×exp(4.736×F1).

Abstract: A multicore fiber comprises a plurality of cores extending along the length of a fiber body. Each of the cores is surrounded by a cladding. The plurality of cores and surrounding cladding provide respective index variations, so as to form a respective plurality of waveguides for conducting parallel data transmissions from a first end of the fiber to a second end. The plurality of cores has a cross-sectional geometry in which the plurality of cores is configured in a polygonal array, in which at least some of the cores are positioned at the vertices of the array. The polygonal array is configured such that neighboring cores in the array are separated from each other by a distance that is sufficient to prevent crosstalk therebetween.

Abstract: Optical fiber refractive index profile designs having an alpha core profile and a negative index trench to control bend loss, are modified by truncating the edge of the alpha core profile and adding a ledge to the truncated core. The result is low bend loss and preservation of low differential mode delay and high bandwidth.

Abstract: An optical fiber, which is less likely to increase its transmission loss even when it is exposed to a high-humidity environment or immersed in water, is provided. The optical fiber comprises a glass fiber and at least two coating layers (a soft layer and a hard layer) coated at the circumference of the glass fiber, wherein the limit-adhesion strength between the glass fiber and the coating layer under a hot and humid environment is 0.5N/10 mm or more. Preferably, the glass-transition temperature of the hard layer is less than 90° C.

Abstract: The invention aims to provide an optical fiber in which light that is input to the clad is easily released to the outside of the clad, and a laser device using the optical fiber. An optical fiber (50) includes a core (51), and a clad (52) coating the core (51). The clad (52) includes a refractive-index varying region (56) in which the refractive index increases in the direction from the inner circumferential side toward the outer circumferential side. In this structure, even when light is input to the clad (52), the light that has reached the refractive-index varying region (56) of the clad (52) is refracted and propagates from the inner circumferential side toward the outer circumferential side of the clad (52). Accordingly, light that is input to the clad (52) is easily released to the outside of the clad (52).

Abstract: A optical fiber (1) includes a fiber core (11); a cladding layer (12) enclosing the fiber core; a first buffering layer (13) attached to the cladding layer; a colored layer (15) coating on the first buffering layer; a second buffering layer (15) enclosing the colored layer; and wherein the second buffering layer is transparent and the colored layer can be observed from an outside.

Abstract: A trench optical fiber that stably realizes a small transmission loss includes (1) a core extending in an axial direction while containing an axial center of the fiber, the core having a diameter d1 of 7.0 ?m to 7.4 ?m; (2) a first optical cladding layer surrounding the core and having an outside diameter d2 of 1.67d1 to 2.5d1; (3) a second optical cladding layer surrounding the first optical cladding layer; and (4) a jacket layer surrounding the second optical cladding layer and containing fluorine having a concentration of 0.06 wt % or higher. A relative refractive index difference ?1 of the core with respect to the jacket layer is 0.31% to 0.37%. A relative refractive index difference ?2 of the first optical cladding layer with respect to the jacket layer is +0.02% or larger and smaller than ?1. A relative refractive index difference ?3 of the second optical cladding layer with respect to the jacket layer is ?0.2% or smaller.

Abstract: A Radiation Curable Secondary Coating comprising A) a Secondary Coating Oligomer Blend, which is mixed with B) a first diluent; C) a second diluent; D) an antioxidant; E) a first photoinitiator; F) a second photoinitiator; and G) optionally a slip additive or a blend of slip additives; wherein said Secondary Coating Oligomer Blend comprises: ?) an Alpha Oligomer, which is non-urethane; (?) a Beta Oligomer; which is a urethane or non-urethane. ?) a Gamma Oligomer; wherein said Gamma Oligomer is an epoxy diacrylate.

Abstract: Apparatus and method are provided for transmitting at least one electro-magnetic radiation is provided. In particular, at least one optical fiber having at least one end extending along a first axis may be provided. Further, a light transmissive optical arrangement may be provided in optical cooperation with the optical fiber. The optical arrangement may have a first surface having a portion that is perpendicular to a second axis, and a second surface which includes a curved portion. The first axis can be provided at a particular angle that is more than 0° and less than 90° with respect to the second axis.