Abstract: A cable assembly comprising a fiber optic cable and one or more attachment points to allow one or more tethers to optically connect to optical fibers within the cable. The cable assembly may be used as a drop cable for extending optical connections to a plurality of points. An attachment structure is provided for maintaining the tether to the cable to prevent damage to the tether. The attachment structure provides a loose attachment to allow the tether to move relative to the distribution cable, so the tether can move in a generally translational movement, is able to slightly twist, and to have limited lateral movement during coiling, installation, and removal of the cable assembly. This loose attachment structure may prevent damage to the tether due to forces being placed on the cable, such as during coiling or uncoiling of the cable. In one exemplary embodiment, the attachment structure is attached to the cable and receives the tether.

Abstract: Disclosed are fiber optic cables and assemblies for routing optical networks closer to the subscriber. The fiber optic cables have a robust design that is versatile by allowing use in aerial application with a pressure clamp along with use in buried and/or duct applications. Additionally, the fiber optic cables and assemblies have a relatively large slack storage capacity for excess length. Assemblies include hardened connectors such as plugs and/or receptacles suitable for outdoor plant applications attached to one or more ends of the fiber optic cables for plug and play connectivity.

Abstract: Disclosed is installation of an optical fiber composite electric power cable. An installation method of an optical fiber composite electric power cable includes installing an electric power cable including a conductor and an air-blown installation tube therein at an installation region; connecting tubes of adjacent electric power cables to each other, in an electric power cable connection box; and installing an optical fiber unit into the connected tubes by air pressure. Also, a cable structure used for installing the optical fiber composite electric power cable includes a conductor for electric power transmission; an insulator surrounding the conductor; an air-blown installation tube provided outside of the insulator; and a corrosion-protective layer provided to an outermost layer of the cable.

Abstract: The invention relates to high-strength, abrasion-resistant optical fiber cable having a supplemental layer consisting essentially of a liquid crystal polymer (LCP) to enhance the cable's tensile strength and hermetically seal it, and an outermost encasing layer to protect the LCP supplemental layer from damage that could otherwise diminish the tensile strength or destroy the moisture barrier properties of the cable gained by adding the supplemental liquid crystal polymer layer. The encasing layer is preferably a thin layer of a smooth, non-crystalline thermoplastic that can be easily removed with chemicals that do not affect the properties of the supplemental layer so that the supplemental layer can be made accessible for promoting the formation of hermetically sealed interfaces between the cable and other structures. Cross-head extrusion methods for coating optical fibers with LCP and encasing layers are described along with laser and ultrasonic bonding techniques for fabricating hermetic packages.

Abstract: A conduit bundle includes an inner bundle of first-type conduits extending between inner-bundle first and second ends. The first-type conduits are mutually and adjacently bonded along coinciding portions of their lengths in order to define an inner-bundle rigid region that, as view into a plane orthogonal to the longitudinal axis of the inner-bundle rigid region, exhibits an inner-bundle periphery. A separation structure including a structure wall having structure-wall inside and outside surfaces is provided and the inside surface thereof is bonded to the periphery of the inner-bundle rigid region. The conduit bundle further includes a plurality of second-type conduits. Each second-type conduit includes a rigidly bonded region along at least a portion of the length thereof that is bonded to at least one of (i) the structure-wall outside surface and (ii) the bonded region of another second-type conduit of the plurality of second-type conduits.

Abstract: The present disclosure relates to a telecommunications cable having a layer constructed to resist post-extrusion shrinkage. The layer includes a plurality of discrete shrinkage-reduction members embedded within a base material. The shrinkage-reduction members can be made of a liquid crystal polymer. The disclosure also relates to a method for manufacturing telecommunications cables having layers adapted to resist post-extrusion shrinkage.

Abstract: A composite cable 21 with a plug 22 attached thereto includes optical fibers, metal wires, a tensile strength fiber 21a, and an envelope 21b for enveloping them and the plug 22 includes a ferrule 210 of the plug for connecting the optical fiber, a cable clamp 221 and a Kevler holder 222 (first fixing mechanism) for fixing the tensile strength fiber 21a, and a gasket 223 (second fixing mechanism) for blocking a twist of the envelope 21b and further includes a joint mechanism (227) of a detachable traction cap for pulling the composite cable 21 and inserting the composite cable 21 into piping.

Abstract: A multi-layered laminate armor wrap for use with a various cables is disclosed, the armor wrap having at least one water absorbing fabric layer, at least one polymer layer, and at least one layer fabricated from a metal or a metal alloy. Each layer in the multi-layered laminate armor wrap is fused or adhered to the adjacent layers to form a fused or sealed laminate armor wrap. A method of making such an armor wrap is also disclosed.

Abstract: A fiber optic cable includes at least one optic fiber; and a buoyancy modifying coating on the at least one optic fiber, the coating comprising at least one microballoon and a matrix material.

Abstract: Optical fiber cable from a Central Office (CO) to a Service Area Interface (SAI) Optical Line Terminal (OLT) box may have a plurality of optical fibers, each fiber having at least one conductive sheath to can propagate an identifying signal. Optical fibers that emit a signal with identifying information, or other useful information, may be advantageous when, for example, the fiber optic cable holds fibers owned by more than one content or service provider. A further advantage may be that a signal may be designated to a particular address, thereby facilitating the installation of fiber optic service to a customer.

Abstract: A buffered optical fiber having an excellent pistoning characteristic compared with a conventional one and a manufacturing method thereof are provided. The buffered optical fiber of the present invention is composed of an optical fiber with a primary coating layer and a secondary coating layer provided on a circumference of a glass optical fiber and a tertiary coating layer having thermoplastic polyester elastomer as the main ingredient provided on a circumference of the optical fiber and is characterized in that an outer diameter of the primary coating layer is 180 to 200 ?m, an outer diameter of the secondary coating layer is 350 to 450 ?m and the product of a thickness of the secondary coating layer of the optical fiber and a force of pulling out the glass optical fiber from the optical fiber is 720 N/mm·?m or more.

Abstract: An optical cable for communication includes at least one micromodule, wherein the micromodule is blocked with respect to the propagation of water. The at least one micromodule includes at least one optical fiber, a retaining element for housing the at least one optical fiber, and a thixotropic filling compound arranged within the retaining element. The filling compound is thixotropic, has a viscosity higher than or equal to 700 Pa·s at zero shear rate and at a first temperature of 20° C., a loss modulus G? lower than or equal to 3000 MPa at 1 Hz and at a second temperature of ?45° C., and is compatible with the retaining element.

Abstract: A hydrocarbon monitoring cable including resistance to development of defects in a fiber optic core thereof. The core defect resistance may be in the form of resistance to defect causing agents of a downhole environment such as hydrogen. This may be obtained through the use of a carbon layer about the fiber optic core. However, in light of the differing coefficients of thermal expansion between such a carbon layer and an outer polymer jacket, an intermediate polymer layer of a third coefficient of thermal expansion may be disposed between the carbon and jacket layers. Thus, the intermediate polymer layer may be of a third coefficient of thermal expansion selected so as to avoid fiber optic defect causing thermal expansion from the downhole environment itself. Additionally, the monitoring cable may include an electrically conductive layer about the fiber optic core that is positively charged to repel other positively charged fiber optic defect causing agents of the downhole environment.

Abstract: An optical cable comprises a cable core (100) containing optical transmission elements (10) surrounding a centrally arranged strain relief element (20). Yarns (31) are arranged as a further strain relief element in a manner surrounding the cable core (100). The entire arrangement is surrounded by a cable sheath (400). A thermoplastic material into which vegetable fibers are embedded as a filler is used as materials for the conductor sleeves (2) of the optical transmission elements, the strain relief elements (20) and the cable sheath (400). The use of such vegetable-fiber-filled plastic materials makes it possible to improve the material properties of conductor sleeve, cable sheath and strain relief elements such as, for example, the shrinkage behavior of materials during production and also the transverse compressive and tensile strength.

Abstract: A fiber optic cable including at least one optical fiber and at least one dry insert disposed within a cavity of a cable jacket and methods for manufacturing the same are disclosed. The dry insert has a first thickness and a second thickness located at different longitudinal locations along the dry insert, where the first thickness is greater than the second thickness. The region of the cable having the first thickness of the dry insert provides and/or increases the coupling level of the at least one optical fiber to the cable jacket. In further embodiments, the optical fiber(s) have a predetermined level of coupling to the cable jacket that is about 0.1625 Newtons or more per optical fiber for a thirty meter length of fiber optic cable.

Abstract: A fiber optic cable can comprise small spheres or balls disposed in the cable's interstitial spaces, for example between the cable's optical fibers and a surrounding buffer tube. The spheres can comprise foam rubber, closed-cell or open-cell porous polymer, or some other soft material. Typical diameters for the spheres can be in a range of 1 to 2.5 millimeters. A soft composition of the spheres can cushion the optical fibers and physically impede water ingress into the cable. Additional fiber protection can arise from the ability of the loose spheres to rotate individually, in a ball-bearing effect. Thus, sphere-to-sphere motion can absorb physical stresses associated with bending, twisting, bumping, and stretching the cable during installation, thereby shielding the fibers from damage.

Abstract: This invention discloses a multi-layered laminate armor wrap for use with a copper or fiber optic cable having at least one water absorbing fabric layer, at least one polymer layer, and at least one layer fabricated from a metal or a metal alloy. Each layer in the multi-layered laminate armor wrap is fused or adhered to the adjacent layers to form a fused or sealed laminate armor wrap. This invention also discloses a method of making such an armor wrap.

Abstract: A water-swellable material is included for water-blocking inside a buffer tube in a cable design, and an adhesive material is provided in or on the water-swellable material. The adhesive material may function as a bonding agent between the water-swellable material and the inside wall of a buffer tube, thus providing coupling of the water-swellable material to the buffer tube. In addition, or alternatively, a second adhesive material may be provided for bonding the optical fibers to the water-swellable material. The adhesive materials may be in the form of a bead or beads and may be foamed or unfoamed.

Abstract: An optical cable which occupies little space and is highly flexible irrespective of the bending direction has a cable sheath and one and only one core, which is surrounded by the cable sheath. The one and only one core contains a plurality of optical waveguides. The optical cable and the core each have a round cross section. The optical cable is designed to produce an optical connection between further optical waveguides. Furthermore, an arrangement for connection of a multiplicity of optical waveguides has an array of connections. The ends of the optical cable can be connected to in each case two of the connections, so that the connections between a multiplicity of further optical waveguides are configurable. A method for production of the optical cable includes the prefabrication of a multi-fiber cable for use in a jumper panel.

Abstract: A fiber optic cable including at least one optical fiber and at least one dry insert disposed within a cavity of a cable jacket and methods for manufacturing the same are disclosed. The dry insert has a first thickness and a second thickness located at different longitudinal locations along the dry insert, where the first thickness is greater than the second thickness. The region of the cable having the first thickness of the dry insert provides and/or increases the coupling level of the at least one optical fiber to the cable jacket. In further embodiments, the optical fiber(s) have a predetermined level of coupling to the cable jacket that is about 0.1625 Newtons or more per optical fiber for a thirty meter length of fiber optic cable.

Abstract: A fiber optic cable including at least one optical fiber disposed within a cavity of a cable jacket and methods for manufacturing the same are disclosed. The cavity has a first cavity cross-sectional area and a second cavity cross-sectional area located at different longitudinal locations along the cable, where the first cavity cross-sectional area is greater than the second cavity cross-sectional area. The region of the second cavity cross-sectional area of the cable provides and/or increases the coupling level of the at least one optical fiber to the cable jacket. In further embodiments, the fiber optic cable is a dry cable having one or more dry insert within the cavity for cushioning and/or optionally providing water-blocking for the cable.

Abstract: A securement system includes at least one retention arrangement securing a tether to a distribution cable; and a release device secured to the distribution cable. The release device extends along at least a portion of the length of tether. Pulling the release device away from the distribution cable disengages the retention arrangement to free the tether from the distribution cable. Multiple retention arrangements can be used to secure the tether.

Abstract: A tubular and a jacketed cable combination includes a strip of material helically wound about itself to form a tubular structure having an inside dimension and an outside dimension, one or more optic fibers disposed within a filler material, a jacket disposed about the filler material to protect the same and an affixation between the jacket and the tubular and methods of making the combination and the cable.

Abstract: Between an optical fiber (LF11, LFB12, LFB13) and a surrounding core covering (AH11, AH12, SB13) of an optical transmission element (OE11 to OE13) there is at least one dry and compressible fixating element (FE11 to FE13), which surrounds the optical fiber totally or partially, and which exerts a defined contact pressure against the core covering and against the optical fiber for fixating the optical fiber in the longitudinal direction of the transmission element. The fixating element is further formed and positioned in such a way, that position changes of the optical fiber due to bending or elongation are possible. In this way, unallowable attenuation increases in the optical fiber due to bending or position changes can be avoided.

Abstract: An optical tube assembly having at least one optical waveguide, at least one dry insert, and a tube. The at least one optical waveguide is disposed within the tube and generally surrounds the at least one optical waveguide. In one embodiment, the dry insert has a first layer comprising a felt having at least one type of non-continuous filament. The dry insert may also include a plurality of water-swellable filaments. In another embodiment, a dry insert has a first layer, a second layer, and a plurality of water-swellable filaments. The first and second layers are attached together at least along the longitudinal edges thereof, thereby forming at least one compartment between the first and second layers and the plurality of water-swellable filaments are generally disposed in the at least one compartment. The dry insert also is advantageous in tubeless cable designs.

Abstract: A low cost, high performance, low profile flexible reinforcement member that can be used for both optical and copper communications cable. The reinforcement members made according to the preferred process are more rigid than known reinforcement members, but are less rigid than glass pultruded rods. Communications cables utilizing these members are lightweight and exhibit an improved combination of strength and flexibility compared to traditional communications cables. Further, these communication cables may then be installed into underground ducts using more economical and faster installation techniques.

Abstract: A buffer tube having therein a ribbon stack formed of optical fiber ribbons, and at least one filler ribbon provided on at least a top or bottom surface of the ribbon stack. The filler ribbon is provided to increase coupling between the ribbon stack and the buffer tube and to reduce fiber attenuation.

Abstract: A modular cable unit for oilfield wireline includes multiple cable modules. The cable modules are interchangeable to achieve a modular cable unit with desired telemetry and electrical properties to suit a specific application. The cable modules can be an optical fiber module, a power cable or an opto-electrical module assembly. The cable modules that make up the modular cable unit are preferably arranged in a triad configuration defining a substantially triangular tangent periphery and are surrounded by a polymeric casing having a circular periphery. The triad configuration of the modular cable unit contributes to an improved mechanical strength. A floating-tube type optical fiber element with improved mechanical strength is also disclosed.

Abstract: A method and apparatus are described, which permit a simple, rapid manufacture of an end of an optical fiber bundle. According to the method a metallic sleeve is placed on an end section of the bundle, the end section with the sleeve on it is positioned in a shaping tool without pressing the sleeve and then pressure is exerted on the sleeve exclusively in a radial direction by press jaws of the shaping tool. In the optical fiber bundle made by the method the outer optical fibers (4?) of the optical fiber bundle (1) are embedded at least partially in the sleeve material. The apparatus for making the end of the bundle (1) with the sleeve (10) has a shaping tool (20) including at least two radially movable press jaws (22a-22f) that substantially surround the sleeve (10).

Abstract: Self-healing cable apparatus and methods disclosed. The self-healing cable has a central core surrounded by an adaptive cover that can extend over the entire length of the self-healing cable or just one or more portions of the self-healing cable. The adaptive cover includes an axially and/or radially compressible-expandable (C/E) foam layer that maintains its properties over a wide range of environmental conditions. A tape layer surrounds the C/E layer and is applied so that it surrounds and axially and/or radially compresses the C/E layer. When the self-healing cable is subjected to a damaging force that causes a breach in the outer jacket and the tape layer, the corresponding localized axially and/or radially compressed portion of the C/E foam layer expands into the breach to form a corresponding localized self-healed region. The self-healing cable is manufacturable with present-day commercial self-healing cable manufacturing tools.

Abstract: Described are new cable designs for indoor installations wherein the cable comprises a dual-layer optical fiber buffer encasement of acrylate resin. The buffer encasement has an acrylate compliant inner layer that protects the fiber and minimizes stress transfer to the fiber; and a hard, tough acrylate outer layer that provides crush resistance. The dual-layer optical fiber buffer encasement is wrapped with reinforcing yarn and encased in an outer protective jacket. A dual jacket embodiment adapted for indoor/outdoor installations is also described.

Abstract: A conductor module (M) comprises a jacket (E) tightly accommodating, in the manner of tubing, at least two flexible conductors (C). The conductors (C) are coated with a small amount of oil (H) having a viscosity strictly less than 100 millipascal second (mPa.s) so as to allow control of the slippage of the jacket (E) in relation to the conductors (C) and longitudinal impenetrability inside the module (M).

Abstract: An optical phase modulator made of lithium niobate or the like phase-modulates the output light of a single-wavelength laser light source 20 that emits CW light, and the phase-modulated light is inputted to a dispersion medium 22. The positive chirp and negative chirp of light to which frequency chirp is applied by phase modulation draw near in the dispersion medium and an optical pulse is generated.

Abstract: A fiber optic cable includes multiple optical fibers extending from a low-pressure environment into a high-pressure environment. At a junction region, the optical fibers are substantially free of any coating, while the fibers include a coating in the low- and high-pressure regions. The fibers are metallized in the junction region, and an epoxy layer is bonded to the metallization. A protective, conductive housing is positioned around the cable. The fibers in the low-pressure region are coupled to communications electronics, and the pattern is repeated as needed to form a needed length of communication cable.

Abstract: An optical fiber cable that sustains reduced increase in transmission loss and optical fiber breakage when subject to external pressure exerted thereon, comprises an aggregate of elements including central buffer filaments disposed in the center part of the optical fiber cable and a plurality of optical fibers disposed around the central buffer filaments, as well as circumferential strength filaments disposed around the outer periphery of the aggregate of elements, and a sheath covering the circumferential strength filaments.

Abstract: A fiber optic cable has at least one optical fiber, at least one strength member having a major strength member dimension, and a cable jacket. The cable jacket has two major surfaces that are generally flat and includes a cavity with a cavity minor dimension generally orientated with a minor dimension of the fiber optic cable, wherein the at least one optical fiber is disposed within the cavity. In one embodiment, the cavity minor dimension of the fiber optic cable is about the same size or larger than the strength member dimension that is generally aligned with a minor dimension of the cable, thereby allowing access to the cavity when the fiber optic cable is entered while inhibiting damage to the at least one optical fiber. Fiber optic cables of the present invention are also suitable as a portion of a cable assembly.

Abstract: Disclosed are fiber optic assemblies for adding additional nodes to a communication network. The fiber optic assemblies include a plurality of optical fibers and a plurality of electrical conductors for transmitting power with a protective sheath covering at least a portion of the same. The fiber optic assembly also includes an optical stub fitting assembly having a rigid housing attached to a optical portion of the composite cable, thereby furcating one or more optical fibers of the fiber optic cable into one or more optical fiber legs. One or more of the optical fiber legs may include one or more optical connector attached thereto. Optionally, the fiber optic assembly may further include a coaxial adapter for transmitting power.

Abstract: A tight-buffered optical fiber includes an optical fiber, at least a first buffer layer of a polymer material enclosing the optical fiber, and a plurality of strength members embedded in the first buffer layer and longitudinally disposed around the optical fiber. A second buffer layer of polymer material may also be formed to enclose the first buffer layer. The first and second buffer layer may be made of acrylate and may be either radiation or thermally curable. The second buffer layer may also have a plurality of strength members embedded in it and longitudinally disposed around the optical fiber.

Abstract: A fiber optic conduit for use in a hostile environment includes an axial tube. The axial tube comprises a corrosion resistant material and is operable to receive one or more optical fibers. The fiber optic conduit further includes a hydrogen barrier shell that is disposed in contact with the axial tube. The hydrogen barrier shell comprises a material that is capable of reducing hydrogen permeation through the fiber optic conduit and has a thickness of at least approximately one-thousandth of an inch.

Abstract: A fiber optic cable having at least one optical fiber such as a microstructured bend performance optical fiber disposed within a protective covering. The protective covering is highly flexible and the fiber optic cable has extremely low delta attenuation when aggressively bent compared with the conventional fiber optic cable designs. By way of example, the delta attenuation of one fiber optic cable design is about 0.33 dB or less when wrapped 3 turns about a 7.5 millimeter mandrel at a reference wavelength of 1625 nanometers. Other variations of the present invention include a connector attached to the fiber optic cable.

Abstract: A drop cable includes a jacket having first and second opposing sides. The first side has a concave surface. At least one strength member is disposed in the jacket. An optical transmission component is disposed within the jacket and proximate the concave surface. The optical transmission component includes a plurality of optical fibers.

Abstract: A fiber optic cable includes a messenger section having at least one strength member, a carrier section having at least one optical fiber therein, and a common jacket that forms a common jacket. In one embodiment, the carrier jacket has a preferential tear portion adjacent to the at least one optical fiber with a substantially continuous outer surface in the carrier jacket adjacent to the preferential tear portion. The preferential tear portion may be defined by at least one of: at least one internal void, at least one weld line, and at least one wing extending from a tape disposed about the one or more optical fibers. Various alternatives are possible. For example, the carrier jacket may also or alternatively include at least one gripping area extending for enhancing the gripping of the carrier section when pulling apart the carrier section and messenger section.

Abstract: Optical cable, in particular for submarine connections. A water blocking resin filling composition of reduced hardness is disposed into interstices. Preferably, the resin composition is a polyurethane resin having less than about 35% by weight of a polyol/polyisocyanate mixture and about 60% to about 90% by weight of a mineral oil. The polyurethane resin preferably has less than about 12% by weight of a coupling agent. The cable has an optical core surrounded by a plurality of metallic wires and an outer polymeric sheath. The optical core is of the “tight” type with a plurality of optical fibers embedded into a polymeric matrix disposed around a strength member.

Abstract: A wireless PC card includes a housing portion including a width and a lens extending substantially the width of the housing portion; a light pipe housed by the housing portion; a substantially flat plug portion extending from the housing portion and configured to be received by a socket of a portable computer for communicating the PC card with the portable computer; an antenna for sending and receiving a wireless signal connected to the housing portion; and a circuit board including an illumination device and electronics to cause the illumination device to emit flashing illumination, causing the lens to emit flashing illumination via the light pipe while the PC card searches for a wireless signal and emit steady state illumination, causing the lens to emit steady state illumination via the light pipe while the PC card maintains a sufficient wireless signal connection.

Abstract: The present disclosure relates to a telecommunications cable having a layer constructed to resist post-extrusion shrinkage. The layer includes a plurality of discrete shrinkage-reduction members embedded within a base material. The shrinkage-reduction members can be made of a liquid crystal polymer. The disclosure also relates to a method for manufacturing telecommunications cables having layers adapted to resist post-extrusion shrinkage.

Abstract: A method includes incorporating an optical fiber into a buffer tube, wherein the buffer tube has a first length. The buffer tube contains the optical fiber and a filler compound to create a buffer tube assembly. The buffer tube assembly is heated to an elevated temperature for a period of time, wherein the first length of the buffer tube decreases to a second length, such that extra optical fiber length is created relative to the second length. The buffer tube assembly is cooled to stabilize the second length and to retain the excess fiber length in the buffer tube.

Abstract: A securement system includes at least one retention arrangement securing a tether to a distribution cable; and a release device secured to the distribution cable. The release device extends along at least a portion of the length of tether. Pulling the release device away from the distribution cable disengages the retention arrangement to free the tether from the distribution cable. Multiple retention arrangements can be used to secure the tether.

Abstract: An optical aerial line has an optical cable extending parallel to an aerial electrical conductor and lashed to the electrical conductor by means of securing elements, wherein the securing elements have at least two binders helically wound onto the electrical conductor and the optical cable, and wherein the number of said binders, the tension of application of said binders, and the lashing pitch are selected so as to have a binding force of at least 5 kg/m, so as to avoid lateral displacements of the optical cable.

Abstract: Between an optical fiber (LF11, LFB12, LFB13) and a surrounding core covering (AH11, AH12, SB13) of an optical transmission element (OE11 to OE13) there is at least one dry and compressible fixating element (FE11 to FE13), which surrounds the optical fiber totally or partially, and which exerts a defined contact pressure against the core covering and against the optical fiber for fixating the optical fiber in the longitudinal direction of the transmission element. The fixating element is further formed and positioned in such a way, that position changes of the optical fiber due to bending or elongation are possible. In this way, unallowable attenuation increases in the optical fiber due to bending or position changes can be avoided.

Abstract: A method for treating a polymeric optical element which includes the steps of mounting a polymeric optical element into a chamber, injecting a compressed gas as an annealing medium into the chamber and annealing the polymeric optical element and removing the annealing medium from the chamber. The present method provides a new way of preventing disadvantageous molecular orientation and residual stress which causes a deterioration in the optical properties of the polymeric optical element.