Abstract: The present invention provides a method of coupling an electrical signal to an optical fiber (14). The method includes encapsulating an electrical connector (21), an optical semiconductor device (18,36), and a fiber optic cable (14) all in one body (23,38,41,42). The semiconductor device (18,36) is electrically coupled to the electrical connector (21), and is also aligned to the fiber optic cable (14). The components are encapsulated in one single body (23,38,41,42). The single body (23,38,41,42) permanently maintains the alignment. The electrical connector (21) portion of the body (23,38,41,42) provides an easy means to couple the fiber optical cable (14) to electrical signals.

Abstract: The invention makes it possible to construct large screens by associating several image intensifier modules.A module comprises an input face (2) receiving the image to be intensified, an output face (10) reconstituting the intensified image and a bundle (8) of optical fibres.The process according to the invention consists of producing bands (16) of optical fibres, each band corresponding to a line or row of the image and collectively put into place the non-contiguous ends (12) of the output face in a matrix output support (14). The latter can be obtained either by moulding, or by constructing beforehand injection moulded strips, which are then introduced into a grid or grating.

Abstract: A protected fiber optical splice and a method for making the protected splice. The protective structure encapsulates first and second spliced optical fibers. The fibers are preferably fusion spliced. The protective structure includes a rigid tube surrounding the splice and its adjacent regions of the spliced fibers. A plastic such as an epoxy or moldable plastic is injected into the tube between the substantially axially centered fibers and splice, and the interior wall of the tube. Two molding fixtures are preferably surrounding the two ends of the tube, for injecting the moldable plastic into the tube and for shaping the portions of the structure external to the the tube ends.

Abstract: Disclosed is a method of forming a doped glass body. The glass body is formed by adding a dopant to a glass preform, at least part of which has interconnective pores. The porous preform is immersed in a solution of a salt of the dopant dissolved in an organic solvent having no OH groups. The solvent is removed, and the porous glass preform is heat treated to consolidate it into a non-porous glassy body containing the dopant dispersed throughout at least a portion of the body. An OH-free solvent is selected because of its beneficial effect on the preform during the drying step. Whereas OH-containing solvents such as water and alcohol caused cracking and/or flaking of the outer surface of the porous preform following the drying step, an undamaged surface is formed by the present invention.

Abstract: A flexible, clad, monofilament optical conduit having a flexible light transmitting polymeric core having a relatively high refractive index which is surrounded by a shrunk, heat shrinkable cladding having a relatively low refractive index in comparison to that of the core and which has a relatively small, uniform gap between the outer periphery of the core and the inner periphery of the heat shrinkable cladding, and a method of manufacture whereby a plurality of such conduits are simultaneously produced by polymerization of the conduit core forming material within a length of unshrunken heat shrinkable material which in turn is contained within a relatively thick, durable protective tubing and removal of the relatively thick protective tubing subsequent to polymerization and then shrinking the heat shrinkable material to form a relatively uniform gap between the core and the clad.

Abstract: A drawn optical fiber (21) is provided with inner and outer layers (42,44) of coating material to protect the optical fiber during handling and use. The coating materials are such that they are characterized by being curable upon exposure to different portions of the light spectrum. In a preferred embodiment, the coating material of the inner layer includes a photoinitiator which absorbs light in the visible portion of the light spectrum whereas the outer coating material of the outer layer includes a photoinitiator which absorbs light in the ultraviolet light portion of the light spectrum.

Abstract: The invention relates to a method of heat processing particles of glass. A first current of a mixture of a combustible gas and a gas capable of oxidizing the combustible gas is introduced into a substantially cylindrical chamber from its lower end. The combustible gas is ignited to form a flame in which the gases have a speed of less than 10 m/s. The resulting flame creates a heat processing zone in the chamber. A quenching zone is provided by a second current of gas introduced into the chamber adjacent the chamber side wall such that it swirls around the flame. Particles of glass are then introduced at the lower end of the chamber and these particles contact the flame in the heat processing zone and are then directed to the quenching zone where they are hardened and from which they are collected.

Abstract: When effecting a fusion splice between two optical fibres, end parts of the two fibres are introduced transversely into opposite ends of an open-ended channel in a surface of a rigid elongate support member having at a position intermediate of its ends and in the surface a transversely extending open-ended slot for temporarily accommodating the electrodes by which fusion splicing is to be effected. After fusion splicing of the fibres and withdrawal of the electrodes, any space in the channel not occupied by the fushion spliced fibres and the transversely extending slot are filled with a curable material which is permitted or caused to set. A preformed elongate lid is secured to the surface of the support member 1 and the support member and lid provide permanent protection for the fusion splice.

Abstract: In a blood gas sensing probe, a cylindrical sleeve contains an optical fiber. The end of the optical fiber is withdrawn into the sleeve thereby creating a receptacle at the end of the sleeve. A sensitive dye, HOPSA for example, is encapsulated in a gel and deposited in the receptacle to form the probe. In making the probe, the end of the optical fiber is in the same plane as the end of the sleeve in which it is placed. The dye and gel contact the combined ends of optical fiber and sleeve. The fiber is withdrawn into the sleeve thereby creating a vacuum which is filled by the dye and gel.

Abstract: A method is presented for writing a permanent spatially periodic phase-matching second-order non-linearity grating in an optical waveguide. Single frequency exciting radiation is launched in a pair of guided modes of the waveguide in the presence of an external DC electric field applied in a direction transverse to the waveguide. The exciting radiation may be either co-propagating or counter-propagating. The above method may be refined by performing it once for an estimated value of exciting radiation frequency, testing the waveguide to determine error in the chosen estimate, erasing the grating and re-performing the method using a corrected value for the frequency of the exciting radiation.

Abstract: A process for producing fine powder, which includes entraining a starting powder material in a carrier gas, injecting the starting powder material using the carrier gas into a high temperature jet to form a high velocity stream of molten droplets, fragmenting the resulting high velocity molten droplets by impacting against a substrate wherein the temperature of the substrate is above the melting point of the powder material, to form smaller droplets, and allowing the resulting fragmented smaller droplets to spheroidize and solidify in flight.

Abstract: A plastic light conduit of cross-linked polymer material having good light transmitting characteristics, without voids or noticeable bubbles, is disclosed. Also disclosed is a method of manufacture and an apparatus, involving progressive heating of reactive monomer mixture in a tube which is submerged in a progressive reactor utilizing cold oil to maintain a cold, non-reacting zone, and hot water to create a hot zone that causes reaction, while simultaneously carrying away the excess exothermic heat of reaction.

Abstract: Apparatus for use in terminating an optical fibre F in the bore of a tubular connector body C comprises a movable support 1 having first gripping means 5 for holding a tubular connector body in a fixed position on the support, second gripping means 7 for holding an optical fibre in a predetermined position in which the fibre extends through and protrudes from the bore of the connector body when so held, and a handle of thermally insulating material. A first mounting 10 for temporarily supporting the movable support 1 is of such a form that it facilitates ready positioning of the connector body C and optical fibre F. A second mounting 20, to which the movable support 1 is transferred from the first mounting 10, incorporates heating means for hardening of heat-hardenable adhesive employed to secure the optical fibre in the connector body. Reduction in the level of manual dexterity needed to ensure consistent satisfactory terminations can be achieved.

Abstract: A process for producing scintillating optical fibres consisting in dissolving in a monomer having aromatic cycles, in particular vinyltoluene or styrene, 1-phenyl-3-mesityl-2-pyrazolin (PMP) doping molecules and a chain transfer agent, especially glycoldimercapto acetate, in heating the mixture so as to cause it to polymerize and to effect the final sheathing and stretching of the polymer so as to produce the optical fibres. The process of the invention enables fibres to be obtained which have a very small diameter (in the region of 30 to 50 microns) with a reduced molar extinction in a proportion exceeding 100 in relation to conventional scintillating fibres; it also totally suppresses diaphotic phenomena when the fibres are arranged to form a beam.

Abstract: A plastic optical fiber comprising a core polymer having a refractive index of n.sub.1, which comprises a polymer of .alpha., .beta.-unsaturated carboxylic acid fluoroalkylester represented by the general formula [I] as the main monomer, and a clad copolymer having a refractive index of n.sub.2, which comprises perfluoro(2,2-dimethyl-1,3-dioxole) as the main monomer, and which satisfies the relationship of (n.sub.1 -n.sub.2 .gtoreq.0.01): ##STR1## wherein X represents CH.sub.3, H, D, F, Cl, or CF.sub.3, Y represents H or D, and Rf represents a fluoroalkyl group having a linear or branched chain. The optical fiber is prepared by a melt-extrusion method. The optical fiber has excellent light transmitting properties, and it is suitable as an optical fiber for long distance light communication.

Abstract: A star-coupler and a method for constructing the star-coupler employing injection molding technology are disclosed. The star-coupler may be constructed from a single injection molded block or a plurality of mating sections, and is supplied with a plurality of input ports and a plurality of output ports. Each input port as well as each output port is connected to at least one channel. The channels are filled with a fiber optical core material and the single block or mating sections are fabricated from fiber optical core material. Alternatively, a separate cladding material may be coated on the surfaces of the block or mating sections which define the channels. Optical signals are guided and confined by the core and cladding material from input ports to output ports along the channels.

Abstract: A method of producing an optical multi-fibre cable element provided with a secondary sheathing by extruding (1) a loose secondary sheathing (10) around a fibre bundle (9) and providing the fibres with a desired extra length with respect to the secondary sheathing. To avoid variation in fibre length in the production of cable elements the secondary sheathing (10) together with the fibre bundle (9) is twisted (12) around its axis after the extrusion step (1) at least to such an extent that the longitudinal sliding of the fibres with respect to each other is prevented in the twisted fibre bundle and that the stretching of the fibres in the fibre bundle at the step of providing the extra length (3; 18) is kept within the elastic range of the fibres.

Abstract: A method of fabricating an optical branching and coupling device includes the steps of preparing at least a pair of coated optical fibers; partly stripping the coating of the optical fibers; and fixedly inserting the coating stripped portions of the optical fibers into a pair of comb-shaped grooves under a condition prior to a unification step which is free from tension and torsional stress in an optical axial direction to bring the coating stripped portions into contact with each other between the comb-shaped grooves. The method also includes the steps of melting the coating stripped portions thus contacting each other by heating to unify the coating stripped portions and extending the coating stripped portions in the optical axial direction while in the melted state.

Abstract: A composition for use in injection molding powder metallurgy, is provided by applying mechanical sphericalization to a metal powder of an irregular shape and having an average grain size of not more than 50 .mu.m to form a sphericalized metal powder, and then mixing and kneading a binder of not more than 9 parts by volume relative to 11 parts by volume of the sphericalized metal powder.

Abstract: An active device mount 1, comprises a body 2 for receiving an optoelectronic device 10 and having a socket 11 for receiving a holder 15 for an optical fiber, an interior and an entrance end of the socket 11 being covered from the entrance end, the lip 17 having exterior mold vestiges 54, and the material 16 preventing a rubbing mark from being applied on the holder 15 by the socket 11. Very small apertures either in the face of body 2 as at 58 or in the side wall of body 2 as at 78 are filled with material 16 during molding to preclude rotation of the material 16 relative to body 2.

Abstract: After fusion splicing of optical fibers, the splice area is positioned within a two-part transparent mold. Light-curable epoxy is injected into the mold and surrounds the splice area. A visible light source shines through the mold, which is preferably made of transparent plexiglass, thus allowing the epoxy to harden. The mold is opened and the rejacketed cable is removed. In order to ensure that the original jacket material at the cable ends does not separate from the epoxy rejacketing material, a heat-shrinkable tube may be installed over the rejacketed splice area.

Abstract: A twisted FRP structure having sufficient strength and flexibility is produced by providing a rod member disposed centrally and twist a plurality of side strands twisted around the rod member in the same direction at a predetermined pitch. At least the side strand includes a composite strand having an FRP element from by impregnating fibers with an uncured thermosetting resin and a thermoplastic coating on such FRP element, the thermosetting resin being cured after the side strands are twisted around the rod member. The twisting pitch is not less than 25 times the outside diameter of the FRP element in the side strand.

Abstract: The invention relates to a method of producing an optical cable in which at least one optical waveguide fed forward from a supply reel is provided with a loosely surrounding jacket by means of extrusion, whose length is subsequently reduced relative to the length of the optical waveguide travelling through the expander and is thereafter wound-up. The excessive length of the optical waveguide is consequently distributed uniformly along the overall length of the optical cable, because of the fact that the optical waveguides paid-out from the supply reel are stranded before they are fed into the extruder.

Abstract: Mechanically robust star couplers of polymer optical waveguides having low insertion losses and small fluctuations between the individual output fibers are obtained if polymer optical waveguides are arranged in parallel in the middle region of an apparatus and fused with one another under pressure and with the supply of heat. The optical cladding of the polymer optical waveguides has been previously removed. The method is easy and cost-effective. The apparatus is composed of a lower part with a channel recessed therein and an upper part with a male die located therein, which male die corresponds in its shape to the shape of the channel.

Abstract: The invention discloses fuel nuggets with high heat value which is virtually dust-free, and a method of making the same. The nuggets are preferably made of scrap particleboard made of wood particles bonded together by a urea/formaldehyde adhesive. The scrap is hogged and shaped into roughly spherical nuggets of a preselected size suited for automated furnaces. The nuggets are then coated with an aqueous urea solution and then oven-dried to achieve a preselected moisture content.

Abstract: A method of forming an optical fiber defining an axis, the fiber having a dipolar dopant wherein a substantial number of the dipoles of the dopant are oriented in essentially the same direction along the axis of the fiber; the method comprising the steps of providing a vessel having a spinneret, establishing a substantially constant electric (or magnetic) field adjacent to, axially aligned with and downstream of the spinneret, forming a prefiber homogenous liquid mixture of at least one dipolar dopant and at least one polymer in the vessel, extruding the prefiber through the spinneret, drawing the extrudate through the electric (or magnetic) field to generally align the dipoles in the same direction and simultaneously elongating the extrudate while it is still in the fluid state by drawing the extrudate.

Abstract: In a blood gas sensing probe, a cylindrical sleeve contains an optical fiber. The end of the optical fiber is withdrawn into the sleeve thereby creating a receptacle at the end of the sleeve. A sensitive dye, HOPSA for example, is encapsulated in a gel and deposited in the receptacle to form the probe. In making the probe, the end of the optical fiber is in the same plane as the end of the sleeve in which it is placed. The dye and gel contact the combined ends of optical fiber and sleeve. The fiber is withdrawn into the sleeve thereby creating a vacuum which is filled by the dye and gel.

Abstract: A method is described for forming hollow particles, or shells, of extremely small size. The shell material is heated to a molten temperature in the presence of a gas that is at least moderately soluble in the shell material, to form a solution of the molten shell material and the soluble gas. The solution is atomized to form a multiplicity of separate droplets that are cooled while in free fall. Cooling of a droplet from the outside traps the dissolved gas and forces it to form a gas bubble at the center of the droplet which now forms a gas-filled shell. The shell is reheated and then cooled in free fall, in an environment having a lower pressure than the gas pressure in the shell. This causes expansion of the shell, to form a shell having a small wall thickness compared to its diameter.

Abstract: An apparatus for terminating an optical fiber includes a resiliently deformable spherical member disposed in contact with a front end of a bore of an optical fiber contact body. Subsequent to softening an adhesive disposed within the contact body bore, an optical fiber is inserted through the bore and the adhesive until the fiber contacts the blocking member and deforms it. The resiliency of the blocking member causes adhesive to be wiped off the front face of the fiber being terminated and into an annulus formed between an outer cylindrical surface of the fiber and an inner cylindrical surface of the bore, and causes the fiber front end to be recessed a predetermined amount from a front end of the contact body.

Abstract: An active device mount 1, comprises, a body 2 for receiving an optoelectronic device 10 and having a socket 11 for receiving a holder 15 for an optical fiber, an interior and an entrance end of the socket 11 being covered with a material 16 molded with a lip 17 projecting from the entrance end, the lip 17 having exterior mold vestiges 54, and the material 16 preventing a rubbing mark from being applied on the holder 15 by the socket 11.

Abstract: An optical simulator 10, shaped to be interchangeable with a complimentary connector 7 that intermates with an optical connector housing 6 having an optical emitter 4 and an optical detector 5, comprises an alignment fixture with connectors for intermating with the optical emitter 4 and the optical detector 5. Included is an optical fiber 11 formed in a loop and installed within the alignment fixture 12 with a first end face 15 of the loop 11 aligned with the emitter 4 and a second end face 16 of the loop 11 aligned with the detector 5 of the optical connector 6. The simulator 10 is a solid molded body of an electrically insulating material. The optical fiber formed in a loop 11 further comprises an optical fiber having a rigid thin coating of electroplated metal 14.

Abstract: A multifilament type plastic optical fiber having a substantially rectangular cross-section and an islands-in-the-sea structure in which 100 to 10,000 islands are arranged in the sea, wherein the respective islands have a substantially circular cross-section and a core-sheath structure, the islands are arranged in a zigzag-stacked structure, the core occupaney ratio in the multifilament type optical fiber cores section is at least 50% and the brightness index value I which is defined by the following (1), is at least 4.5.times.10.sup.-2 : ##EQU1## wherein S stands for the core occupancy ratio in the multifilament type optical fiber, .alpha. stands for the transmission loss (dB/m) per meter of the multifilament type optical fiber, NA stands for the numeral apertures, and L stands for the length (m) of the used optical fiber.

Abstract: An injection-molded connector for single-mode optical fibers includes two mating plugs having aligned fiber-receiving holes. To keep transmission losses in the connector at an acceptable level, the eccentricity of each hole relative to its plug profile must be maintained within a fraction of a micron. The mold utilized to form the plugs includes a dual-eccentric-cam adjustment mechanism that comprises nested conically shaped cams. In a method for fabricating such plugs, rotation of the cams serves to move a part of the mold that positions a hole-forming pin. By rotating this mechanism, the eccentricity of the fiber hole relative to the profile of the molded plug can be established and maintained within the required precision.

Abstract: A star-coupler and a method for constructing the star-coupler employing injection molding technology are disclosed. The star-coupler may be constructed from a single injection molded block or a plurality of mating sections, and is supplied with a plurality of input ports and a plurality of output ports. Each input port as well as each output port is connected to at least one channel. The channels are filled with a fiber optical core material and the single block or mating sections are fabricated from fiber optical core material. Alternatively, a separate cladding material may be coated on the surfaces of the block or mating sections which define the channels. Optical signals are guided and confined by the core and cladding material from input ports to output ports along the channels.

Abstract: An optical fiber cable core (20) which is sold to a cable manufacturer for oversheathing or for incorporation into electrical power aerial cables, for example, includes in a preferred embodiment at least one bundle (23) of optical fibers (25--25). The at least one bundle is disposed in a tubular member (30) which is made of a plastic material suitable for use in relatively wide temperature range. The core is manufactured to cause a predetermined excess length of fiber to be disposed in the tubular member. The excess length of each fiber is such that it is sufficient to avoid undue strains on the fiber as the cable core is exposed to the elements and to forces imparted during handling such as during installation. On the other hand, the excess fiber length must not be so great as to result in undue curvature of the fiber or excessive interactive engagement of the fiber with an inner wall of the tubular member.

Abstract: A connector having a body and a connecting portion is molded within a mold in which an end portion of an optical fiber is fixedly positioned. The end portion of the optical fiber consists of an exposed end portion of a core of the fiber and a terminal portion of a sheath of the fiber adjacent to the exposed end portion of the core. A molten mass of a selected synthetic material is injected into the mold at a melt flow rate of 5g/min, whereby the connector is molded integrally with the end portion of the optical fiber, such that the exposed end portion of the core is bonded to the connecting portion, while the terminal portion of the sheath is bonded to the body of the connector. The mold is maintained at a temperature not higher than the softening point of the optical fiber, and the molten resin mass is maintained at a temperature which is higher than the softening point but is not higher than a temperature 150.degree. C. higher than the softening point.

Abstract: Production of mono- or multimodal lightwave guides from special substrate glasses of the glass system SiO.sub.2 --B.sub.2 O.sub.3 --Al.sub.2 O.sub.3 -- K.sub.2 O--F.sup.-, with partial exchange of the Li.sup.+, Na.sup.+, and/or K.sup.+ ions present in the glass against Cs.sup.+ ions, the substrate glasses having the following compositions (in mol.-%): SiO.sub.2 45-72, B.sub.2 O.sub.3 8-25, Al.sub.2 O.sub.3 1-25, Li.sub.2 O 0-1, Na.sub.2 O 0-2, K.sub.2 O 6-18, MO 0-1 (MO=MgO, CaO, SrO, BaO, ZnO, PbO), in which a portion of the O.sup.- ions present in the glass are replaced by 1-15 mol % F.sup.- ions.

Abstract: A lens array of rod lenses (16), to be used for reading image data in document copier, facsimile, printer, white board scanner, and so on, is made by injection molding of a transparent resin in an already made plastic lens-holding frame (3) having an array of through-holes (2) and gates (1) leading to respective through-holes (2) for injecting melted transparent resin therethrough, both ends of the through-holes having cores (6) and (7) with concave faces.

Abstract: The present invention provides a method of manufacturing an optical fiber of high heat-resisting and light-receiving properties as well as greater flexibility. The optical fiber of the present invention comprises a core made of a setting type transparent silicone rubber, and an outer portion made of a high molecular weight transparent substance whose refractive index is at least 0.02 less than that of the core. Silicon rubber is injected into the cylindrical outer portion and set, and the silicone rubber and the outer portion are thereafter subjected to heat treatment at a temperature of 120.degree. C. or more for at least 1 hour.

Abstract: A method and apparatus for forming a cable which has a supporting member that is provided by an extruder with helically extending grooves or chambers that proceed in changing directions for the acceptance of light waveguides characterized by synchronously rotating the cable elements proceeding an extruder for applying the supporting member and also following the insertion point for the light waveguides. The light waveguides are inserted at a position which is an even-numbered multiple of the distance between reversing points of the chambers of the supporting members from the output of the extruder so that the direction of the chambers at the extruder and at the insertion point, respectively, proceed in the same direction.

Abstract: Light collectors formed by rolling one edge of a sheet of transparent thermoplastic material into an annular configuration, while keeping an opposite edge flat suffer from light collection inefficiency caused by local stretching and thus thinning of the sheet near the annular end, thereby increasing the number of internal reflections experienced by a light ray. This problem is solved by making a light collector that is uniform in thickness, or thicker toward the annular end.

Abstract: A method for manufacturing an optical cable includes simultaneously introducing a light waveguide and filling material into a chamber of a central element with the waveguide having an excess length. Preferably, the central element is moved axially and rotated on the axis and the light waveguide and filling material are passed through a tube which is inserted in the chamber as the central element is moved relative thereto.

Abstract: An optical fiber connector can be easily and quickly assembled by mounting the end of an optical fiber in a thermoplastic adhesive that is heated to a viscosity of between 1000 and 10,000 cp, has an Adhesion-to-Glass Value of at least 10N, and a Shore D hardness of at least 60 at 20.degree. C. The optical fiber connector lends itself to mass-production techniques and can be reused by heating to liquify the thermoplastic adhesive.

Abstract: A method for controlling excess fiber length (EFL) in a loose tube optical fiber buffer tube which includes traversing a just extruded plastic buffer tube, containing optical fibers and a filling compound, through a vertical cooling tower along a buffer tube path of travel in the cooling tower where the cooling tower contains a water blocking device disposed at a predetermined point along the buffer tube path of travel and the water blocking device has a body containing (a) a chamber with inlet and outlet ports, defining a buffer tube path of travel aligned with the cooling tower path of travel, a conical shaped portion circumscribing a part of the buffer tube path of travel and an annulus shaped portion circumscribing the buffer tube path of travel and a portion of the conical shaped portion; (b) a device disposed near the outlet port for providing a stream of gas directed at the buffer tube path of travel; and, (c) a drain port to remove accumulated water from the annulus-shaped portion.

Abstract: An optical waveguide having a core/sheath structure whose sheath comprises a terpolymer based on vinylidene fluoride, tetrafluoroethylene and hexafluorpropylene, is suitable for transmission paths of ca. 10 to 100 m and can also be used at a temperature of above 100.degree. C. without significant reduction of the transmission path.

Abstract: A sheet-shaped photoconductor composed of a plurality of optical fibers is prepared by melt-spinning a spinning dope into optical fibers and, before the as-spun fibers are completely solidified, bonding the fibers to one another along the entire length thereof. The melt-spinning is carried out using a nozzle having a plurality of annularly arranged orifices. The as-spun fibers are arranged linearly in parallel to but not in contact with one another by using a grooved guide, and then the optical fibers are brought into contact with and fusion-bonded to one another by using a fusion bonding guide having a concave curved face in the central portion thereof, and the thus-formed sheet-shaped photoconductor is taken up.

Abstract: A crystalline metal halide optical fiber having a two or a three layer structure is provided. The core consists of relatively small crystals. A crust surrounds the core and has the same composition but consists of relatively large crystals. Optionally, an optical outer crust surrounds the inner crust and has a different composition from the inner crust but has generally the same sized crystals. The differing crystal sizes can be produced from a preform by extruding a crystal at a low uniform temperature at a relatively high speed.

Abstract: A process for the preparation of a membrane comprising bisphenol-based polycabonate wherein at least 25 percent by weight of the bisphenol moieties are tetrahalogenated wherein the halogen is Cl or Br, and the membrane prepared by such process.

Abstract: Process for producing a fiber reinforced plastics linear material like a tension member for optical communication cables. A groove capable of accomodating an optical fiber is formed in the outer surface of the tension member. In accordance with the conventional method, the groove is necessarily formed in parallel along the axial direction of the tension member and, therefore, if the tension member is bent in the state that the optical fiber is placed in the groove, a force due to bending is applied directly to the optical fiber and the transmission loss of the optical fiber is increased.

Abstract: An optical fiber cable (20) includes a core (21) comprising a units a unit (22). The unit is formed by a plurality of optical fibers (24-24) which are assembled together without intended standing. The unit is enclosed in a tube (34) which provides a predetermined packing density and which is substantially parallel to the longitudinal axis of the cable. In one embodiment, a waterblocking material (36) is disposed within the tube to fill the interstices between the optical fibers and between the unit and the tube. The waterblocking material is such that its critical yield does not exceed about 70 Pa at 20.degree. C. and such that it has a shear modulus of less than about 13 KPa at 20.degree. C. The tube is enclosed with non-metallic or metallic strength members and a plastic inner jacket and by another layer of strength members and by a plastic outer jacket.