Abstract: A hermetically sealed optical fiber cable (20) includes a core (21) comprising a plurality of optical fiber ribbons (22,22) disposed within a core tube (30) comprised of a high temperature resistant polymeric material. The core tube is disposed within a hermetic sealing member (40) which comprises a metal of low electrochemical activity having a sealed seam. An outer jacket (50) is disposed about the hermetic sealing member. The core may be filled with a waterblocking filling material (35). The material of the core tube undergoes only limited degradation because of the limited amount of oxygen and/or moisture trapped in the hermetically sealed cable. The filling material and/or other materials of the cable scavenge moisture and oxygen which travel longitudinally of the cable and reach portions of the cable subjected to a high temperature because of a leak in an adjacent steam line.

Abstract: Optical fiber (20) which may be disposed in the form of a ribbon (28,30), for example, is caused to become disposed in a conduit (42) such as a duct which may exist in the field by introducing the optical fiber and a pressurized liquid transporting medium (37) into the conduit. The liquid transporting medium is effective to cause the optical fiber to be moved along in the conduit to cause a leading end of the fiber to emerge from a far end of the conduit and be accessible for connective arrangements, for example.

Abstract: A steam-resistant optical fiber cable (20) includes a core (21) comprising a plurality of optical fiber ribbons (22,22) disposed within a tubular member (30) comprised of a high temperature resistant material. The tubular member is disposed within a hermetic sealing member (40) which comprises a metal of low electrochemical activity having a sealed seam. An outer jacket (50) is disposed about the hermetic sealing member and in a preferred embodiment is characterized by resistance to degradation in high temperature, high humidity environments. The core may be unfilled or filled with a waterblocking material and in a preferred embodiment, a waterblocking member is interposed between the tubular member and the hermetic sealing member.

Abstract: A totally dielectric cable includes a core (21) comprising a plurality of optical fiber transmission media (24--24). The core is enclosed by a core tube (34) which is made of a plastic material and water blocking provisions are provided within the core tube for preventing the longitudinal migration of water. A water blocking tape (44) may be provided in engagement with an outer surface of the core tube and a plastic jacket is extruded thereover. Interposed between the outer surface of the jacket and the core tube are two diametrically opposed pluralities (60--60) of strength members each of which may be made of glass fibers. At least one strength member (62) of each plurality is rod-like to provide compressive as well as tensile strength for the cable. The remaining strength members of each plurality are relatively flexible rovings (64--64) which supplement the tensile strength of the rod-like members.

Abstract: An optical fiber cable (20) which may be used in a high temperature environment for a substantial period of time without degradation of transmission includes an optical fiber core (22) which is enclosed by an inner tubular member (32) having suitable temperature resistant properties. A braided metallic outer tubular member (50) encloses the inner tubular member and provides suitable mechanical protection and strength for the cable. The integrity of the cable and its performance is further enhanced by a corrugated metallic tube having a sealed periphery and being interposed between the inner and outer tubular members to prevent the ingress of liquid contaminants and to provide the cable with flexibility.

Abstract: Optical fiber cables have an inner sheath extruded or otherwise applied to surround optical fibers. If the fibers are coupled to the sheath, substantial shrinkage of the sheath during manufacturing induces microbending losses in the optical fibers. The inventive technique involves choosing a sheath material having a low viscoelastic modulus, typically PVC, and the application of tension thereto during or after extrusion that prevents such shrinkage. This approach typically avoids the necessity of including longitudinal compressive strength members in the cable. A filled optical fiber cable having a flexible gel to prevent water entry advantageously uses the present technique.

Abstract: An optical fiber cable (20) includes a core (21) comprising at least one optical fiber (24) which is enclosed in a tubular member (34) and which includes a sheath system (40). The sheath system includes two strength members 42--42 which extend linearly longitudinally along the cable parallel to a longitudinal axis (29) of the cable. The strength members are enclosed in a plastic jacket (46). The strength members have predetermined relative tensile and compressive stiffnesses. The stiffnesses are such that the strength members are capable of withstanding expected compressive as well as tensile loading and are coupled sufficiently to the jacket to provide a composite arrangement which is effective to inhibit contraction and which controls the position of the neutral axis during bending while providing suitable flexibility.

Abstract: A single mode optical fiber ribbon cable is disclosed. In preferred embodiments, the cable comprises a filling compound having a critical yield stress less than about 70 Pa at 20.degree. C. and/or fibers having a coating that comrises a low modulus (less than about 1.5.multidot.10.sup.6 Pa at 20.degree. C.) inner coating and a high modulus (more than 10.sup.8 Pa at 20.degree. C.) outer coating. Communication cable according to the invention can have low cabling loss, is adapted for array joining, can have high fiber density, and can advantageously be used in short-haul applications such as for metropolitan trunk lines or loop, as well as for long-haul applications.

Abstract: Compressive strain in cabled optical fibers can cause buckling of the fibers and resulting microbending loss. To measure the longitudinal compression in cabled optical fibers, a modulated laser beam is directed through a first fiber and looped back to the origin by a second fiber. Next, the cable is stretched until tensile strain is indicated by a change in phase of the modulated signal. The amount of stretching required indicates the degree of compression on the fibers in the unstretched cable, and hence the amount of excess length of fiber in the cable. To measure excess fiber in relatively long lengths of cable, a portion of the cable can remain reeled, and the strain applied to the unreeled portion. A correction factor can be determined for slippage between the fiber and sheath in the reeled portion.

Abstract: In the manufacture of a lightguide fiber cable (21) in which a lightguide fiber core (32) is loosely disposed in a composite sheath 40 it is important to control the ratio of the lengths of the core and sheath. A core which is shorter than the sheath and which follows a shortened path on a reel may be unduly strained when the cable is installed in the field. This problem is overcome by coupling the core to the sheath by a system (25) which includes a constant speed linear capstan (146) and a relatively large variable speed sheave (150) that is positioned between the linear capstan and a takeup reel (154). The coupling of the core to the sheath is accomplished on the sheave after the sheath is elongated between the linear capstan and the sheave. The coupling and the elongation cooperate to compensate for the inherent shortfall in core length which otherwise would occur when the cable is wound on a reel.

Abstract: An improved optical cable (10) having increased bending flexibilitiy along with increased tensile strength comprises means for controlling coupling between a cable jacket (28) and its reinforcing strength members (26). In one embodiment, a reinforcement bedding layer (23) is applied between a plastic-extruded inner jacket (22) and the outer cable jacket (28). Before extrusion of the outer jacket (28), the reinforcing strength members (26) are helically applied onto the bedding layer with predetermined strength member surfaces (27) making intimate surface contact with the bedding layer. Because the bedding layer is impervious to the plastic extrudant used to construct the outer jacket and is capable of rendering the predetermined strength member surfaces sufficiently inaccessible to the plastic extrudant, encapsulation of strength member lengths (25) containing the predetermined strength member surfaces (27) by the plastic extrudant is prevented.