Abstract:
An assembly for fabricating an optical fiber ribbon from optical fibers that extend in a longitudinal direction includes a spacing device. The spacing device is operative to vary the spacing between the optical fibers in the lateral direction. The spacing device can be a rotatable cylinder having diverging external grooves that respectively receive the optical fibers. A bonding device applies bonding material to the optical fibers to form an optical fiber ribbon, after the spacing between the optical fibers has been varied by the spacing device. In accordance with a method of manufacturing an optical fiber ribbon, optical fibers that extend in a longitudinal are advanced along travel paths defined by the grooves of the spacing guide. The travel paths diverge from one another in a lateral direction that is generally perpendicular to the longitudinal direction so that as the optical fibers are advanced the optical fibers become further spaced apart from one another in the lateral direction. The increased spacing between the optical fibers is maintained by bonding the optical fibers together.

Description:
FIELD OF THE INVENTION 
     The present invention relates to optical fiber ribbons and, more particularly, to the spacing between optical fibers of optical fiber ribbons. 
     BACKGROUND OF THE INVENTION 
     Optical fiber is a very popular medium for large bandwidth applications, and as a result there is a demand for increased numbers of optical fibers. In response to these demands, optical fiber ribbons have been developed. An optical fiber ribbon includes a planar array of optical fibers that extend longitudinally and are laterally adjacent, and the optical fibers are bonded together as a unit. 
     It is conventional for adjacent optical fibers of an optical fiber ribbon to be in an abutting side-by-side arrangement. As a result, the spacing between adjacent optical fibers in an optical fiber ribbon is often less than the spacing between adjacent optical receptacles of optical devices that optically communicate with the optical fiber ribbon. Optical devices that optically communicate with an optical fiber ribbon include optical input or output devices, which respectively introduce optical signals into or receive optical signals from the optical fibers of optical fiber ribbon. It is common to prepare an optical fiber ribbon for attachment to the optical receptacles of an optical input or optical output device by striping the bonding material of the optical fiber ribbon away from one end of the optical fiber ribbon. A sufficient amount of the bonding material is stripped away so that exposed ends of the optical fibers can be manually spaced apart from one another and be respectively received by the receptacles of the target optical device. 
     Often it is necessary for relatively long lengths of optical fibers to be exposed at the end of an optical fiber ribbon to obtain the spacing necessary to connect to the relatively far spaced apart receptacles of the target optical device. The binding material that holds the optical fibers of an optical fiber ribbon together provides some protection to the optical fibers; therefore, the optical fibers that are exposed by the stripping are at a relatively greater risk of being damaged. In addition, long lengths of loose optical fibers that extend from an optical fiber ribbon are at risk of becoming tangled and disorganized, and can be difficult to manually manage. These risks or disadvantages are becoming greater and greater as optical fibers and associated equipment become more densely packaged in response to the increasing demand for optical fibers. 
     SUMMARY OF THE INVENTION 
     The present invention provides methods and apparatus for manufacturing optical fiber ribbons and, more specifically, for manufacturing multipitch optical fiber ribbons. 
     In accordance with one aspect of the present invention, an assembly for fabricating an optical fiber ribbon from optical fibers that extend in a longitudinal direction is provided. The assembly includes a spacing device having spacing guides that are spaced apart from one another in a lateral direction that is generally perpendicular to the longitudinal direction. Each spacing guide is operative for respectively receiving and guiding an optical fiber of the optical fibers. The spacing device is operative to vary the spacing between the spacing guides in the lateral direction. The assembly may further include a moving device for advancing the optical fibers generally in the longitudinal direction through their respective spacing guides so that the spacing of the spacing guides is imparted upon portions of the optical fibers that are downstream from the spacing guides. The assembly may further include a bonding device positioned downstream from the spacing guides and operative for applying bonding material to the portions of the optical fibers that are downstream from the spacing guides. The bonding material bonds the portions of the optical fibers that are downstream from the spacing guides together to form an optical fiber ribbon. 
     In accordance with one aspect of the present invention, the spacing guide includes a wall that extends generally arcuately about an axis that extends generally in the lateral direction. The wall further extends generally in the lateral direction and includes an outer surface that generally extends generally arcuately about the axis and in the lateral direction. The wall defines grooves that are open at the outer surface and extend generally arcuately about the axis, and portions of the grooves function as the spacing guides. The grooves are spaced apart from one another in the lateral direction, and the spacing between the grooves varies with respect to an arcuate direction that is defined about the axis. Those grooves are relatively narrow grooves that originate from a relatively wide groove that is also open at the outer surface and extends generally arcuately about the axis. The narrow grooves diverge Is they extend generally in the arcuate direction away from the wide groove. 
     In accordance with another aspect of the present invention, the assembly for fabricating an optical fiber ribbon includes a frame, and the spacing guide is pivotally connected to the frame for pivoting about the axis. The fabricating assembly optionally includes a cross member that is movably mounted to the frame and can be positioned in close proximity to the outer surface of the spacing guide. The cross member can extend generally in the lateral direction across the grooves so that the cross member cooperates with the grooves to define spacing apertures that respectively receive the optical fibers. The spacing guide can include marks that can be aligned with the cross member to define intervals along the grooves in the arcuate direction. 
     In accordance with another aspect of the present invention, a method of manufacturing an optical fiber ribbon is provided. In accordance with one example of the method, the optical fibers are advanced along diverging travel paths defined by the grooves of the spacing guide. As the optical fibers are advanced the optical fibers become further spaced apart from one another in the lateral direction. In accordance with one example, the advancing of the optical fiber ribbons along the travel paths is facilitated by moving the spacing guide relative to the optical fibers. More specifically, the advancing of the optical fiber ribbons is facilitated by rotating the spacing guide about an axis. The increased spacing between the optical fibers is maintained by bonding the optical fibers together. The increased spacing between the optical fibers can be established over a long length of the optical fibers by establishing translational movement between the optical fibers and the spacing guide. 
     In accordance with another aspect of the present invention, binding material is removed from an optical fiber ribbon to expose portions of the optical fibers of the optical fiber ribbon. The exposed portions of the optical fibers are advanced along the diverging travel paths and are thereafter bonded together to provide a multipitch optical fiber ribbon. As one example, the multipitch optical fiber ribbon includes optical fibers that extend longitudinally and are laterally adjacent. The optical fibers are bonded together by bonding material having opposite first and second ends. A lateral first spacing is defined between adjacent optical fibers at the first end of the bonding material, a lateral second spacing is defined between adjacent optical fibers at the second end of the bonding material, and the first spacing is different from the second spacing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a multipitch optical fiber ribbon connected between optical devices in accordance with a first embodiment of the present invention. 
     FIG. 2 is an isolated, schematic cross-sectional view of the multipitch optical fiber ribbon of FIG. 1 taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is an isolated, schematic cross-sectional view of the multipitch optical fiber ribbon of FIG. 1 taken along line  3 — 3  of FIG.  1 . 
     FIG. 4 is a top plan view of a guide cylinder that is part of a fabricating assembly for manufacturing the multipitch optical fiber ribbon of FIG. 1, in accordance with the first embodiment of the present invention. 
     FIG. 5 is a schematic end elevation view of the guide cylinder of FIG.  4 . 
     FIG. 6 is a schematic view of the fabricating assembly for forming the multipitch optical fiber ribbon of FIG. 1, wherein the fabricating assembly is partially set up for operation and includes the guide cylinder of FIGS. 4 and 5, in accordance with the first embodiment of the present invention. 
     FIG. 7 is a schematic, partial cross-sectional view taken along line A—A of FIG. 6 with the guide cylinder in a first configuration, in accordance with the first embodiment of the present invention. 
     FIG. 8 is a schematic, partial cross-sectional view taken along line A—A of FIG. 6 with the guide cylinder in a second configuration, in accordance with the first embodiment of the present invention. 
     FIG. 9 is a schematic, partial cross-sectional view taken along line A—A of FIG. 6 with the guide cylinder in a third configuration, in accordance with the first embodiment of the present invention. 
     FIG. 10 is a schematic, partial cross-sectional view taken along line A—A of FIG. 6 with the guide cylinder in a fourth configuration, in accordance with the first embodiment of the present invention. 
     FIG. 11 is a schematic view of the fabricating assembly of FIG. 6 in operation, in accordance with the first embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
     FIG. 1 illustrates a multipitch optical fiber ribbon  20  extending in a longitudinal direction between and connected between an optical device  22  and an optical device  24 , in accordance with a first embodiment of the present invention. Each of the optical devices  22 ,  24  can be a wide variety of different optical devices, such as optical transmitters that transmit optical signals into optical fibers and optical receivers that receive optical signals from optical fibers. More specifically, the optical devices  22 ,  24  can include optical/electromechanical systems or switches, optical cross connects, and a wide variety of other types of optical devices that connect to and optically communicate with an array of optical fibers. 
     In accordance with the first embodiment, the multipitch optical fiber ribbon  20  includes a relatively narrow section  26  having opposite relatively narrow ends  28 ,  29 , and a relatively wide section  30  having opposite relatively wide ends  32 ,  33 . In accordance with the first embodiment, the narrow section  26  in isolation is a conventional optical fiber ribbon; therefore, at times the terms narrow section  26  and conventional fiber ribbon  26  are used interchangeably when describing the first embodiment. It is preferred for the multipitch optical fiber ribbon  20  to be generally planar, yet flexible enough so that it can be manually bent into a variety of curved shapes so that it can be routed around various obstacles, or the like. 
     As illustrated in FIG. 1, receptacles of an array of receptacles  38  of the optical device  22  are respectively in receipt of the ends of the optical fibers  36  that extend from the narrow end  28 , and receptacles  40  of the optical device  24  are respectively in receipt of the ends of the optical fibers  36  that extend from the wide end  33 . As will be discussed in greater detail below, different spacing between the optical fibers  36  at the differently sized ends  28 ,  33  allows the multipitch optical fiber ribbon  20  to be conveniently and efficiently connected between the array of receptacles  38  and the receptacles  40 , which are spaced differently. 
     The multipitch optical fiber ribbon  20  include&#39;s a laterally extending array  34  of longitudinally extending optical fibers  36  that extend between the narrow end  28  and the wide end  33 . Each of the optical fibers have opposite ends that respectively protrude from the narrow end  28  and the wide end  33 . The optical fibers  36  are laterally adjacent and are held together by bonding material  42 ,  44 . In FIG. 1, the centerlines of the portions of the optical fibers  36  that are embedded in the bonding material  42 ,  44  are illustrated by dashed lines that extend between the narrow end  28  and the wide end  33 . In accordance with the first embodiment, the array  34  is absent of splices between the optical fibers  36  between the narrow end  28  and the wide end  33 , and none of the optical fibers cross one another between the narrow end  28  and the wide end  33 . 
     A relatively small separation spacing “S 1 ” is defined between the centerlines of adjacent optical fibers  36  in the narrow section  26  of the multipitch optical fiber ribbon  20 , and the separation spacing S 1  is approximately the same as the spacing between adjacent receptacles of the array of receptacles  38  of the optical device  22 . A relatively large separation spacing “S 2 ” is defined between the centerlines of adjacent optical fibers  36  in the wide section  30  of the multipitch optical fiber ribbon  20 , and the separation spacing S 2  is approximately the same as the spacing between the adjacent receptacles  40  of the optical device  24 . The separation spacing S 2  is greater than the separation spacing S 1 , as will be discussed in greater detail below. The spacing between optical fibers of an optical fiber ribbon is often referred to as pitch. Accordingly, the optical fiber ribbon of the first embodiment is referred to as the multipitch optical fiber ribbon  20  because it has more than one pitch. In addition, the narrow section  26  of the multipitch optical fiber ribbon  20  defines a relatively small width “W 1 ” that is smaller than a relatively large width “W 2 ” defined by the wide section  30  of the multipitch optical fiber ribbon  20 . 
     In accordance with the first embodiment, in the narrow section  26  of the multipitch optical fiber ribbon  20  the optical fibers  36  are held together by a homogeneous bonding material  42  that extends between the opposite narrow ends  28 ,  29 . The homogeneous bonding material  42  is best seen in FIG. 2, which is a schematic cross-sectional view of the narrow section  26  of the multipitch optical fiber ribbon  20  taken along line  2 — 2  of FIG.  1 . FIG.  2  and all other cross-sectional views are schematic because, for example, it is preferred for each of the optical fibers  36  to be conventional coated glass fibers, but the coatings are not distinguished from the glass fibers in the figures. 
     In accordance with the first embodiment, the homogeneous bonding material  42  is preferably a polymeric bonding material, and an acceptable design for the narrow section  26  of the multipitch optical fiber ribbon  20  is described in U.S. Pat. No. 4,900,126, which is incorporated herein by reference. Briefly, the homogeneous bonding material  42  is preferably an ultraviolet-curable matrix bonding material, or the like. The homogeneous bonding material  42  material fills the interstices between the optical fibers  36 , binds together the optical fibers, and extends to the outside boundary of the narrow section  26  of the multipitch optical fiber ribbon  20 . 
     A known ultraviolet-curable matrix material from which the homogeneous bonding material  42  is acceptably formed includes a resin, a diluent and a photoinitiator. The resin may include a diethylenic-terminated resin synthesized from a reaction of hydroxy-terminated alkyl acrylate with the reaction product of a polyester of polyethyl polyol of molecular weight of 1,000 to 6,000 with an aliphatic or aromatic diisocyanate, or diethylenic-terminated resin synthesized from the reaction of glycidyl acrylate with a carboxylic-terminated polymer or polyether of molecular weight 1,000 to 6,000. The diluent may include monofunctional or multifunctional acrylic acid esters having a molecular weight of 100 to 1,000 or N-vinylpyrrolidinone. For the photoinitiator, the composition may include ketonic compounds such as diethoxyacetophenone, acetophenone, benzophenone, benzoin, anthraquinone, and benzil dimethyl ketal. In a typical composition, the bonding matrix may include a resin (50-90%), diluents (5-40%), and a photoinitiator (1-10%). All percentages are by weight unless otherwise noted. 
     In accordance with the first embodiment, in the wide section  30  of the multipitch optical fiber ribbon  20  the optical fibers  36  are held together by a composite bonding material  44  that extends between the opposite wide ends  32 ,  33 . The composite bonding material  44  is best seen in FIG. 3, which is a schematic cross-sectional view of the wide section  30  of the multipitch optical fiber ribbon  20  taken along line  3 — 3  of FIG.  1 . In accordance with the first embodiment, the composite bonding material  44  includes longitudinally extending pieces of tape  46  that are positioned on opposite sides of the optical fibers  36 . The composite bonding material  44  further includes adhesive  48  that is positioned between the inner surfaces of the tapes  46  and extends into the interstices between the optical fibers  36 . The adhesive  48  preferably originates as backings on the inside surfaces of the tapes  46 . 
     As will be discussed in greater detail below, in accordance with the first embodiment, the wide section  30  of the multipitch optical fiber ribbon  20  is preferably constructed using a fabricating assembly  70  (FIGS.  1  and  11 ). Central to the fabricating assembly is a spacing device that can be referred to as a spacing guide member, and in accordance with the first embodiment the spacing guide member is in the form of a guide cylinder  50 , which is illustrated in FIGS. 4 and 5. In accordance with the first embodiment, it is preferred for the spacing guide member to have some arcuate characteristics, but it is not necessary for the spacing guide member to be cylindrical. 
     As best understood with reference to FIG. 4, in accordance with the first embodiment the guide cylinder  50  includes generally circular opposite ends  52 ,  54 . The guide cylinder  50  further includes a.cylindrical wall that includes an outer cylindrical surface  56 . The outer surface  56  extends laterally between the opposite ends  52 ,  54  and extends arcuately around an axis that is concentric with an axle  58  about which the guide cylinder  50  can rotate. 
     Defined in the guide cylinder  50  are multiple narrow guide grooves  60   a-f  that diverge from a wide guide groove  62 . Each of the grooves  60   a-f ,  62  are open at the outer surface  56  and extend arcuately partially around the axle  58 . Although the guide cylinder  50  is described as including six narrow guide grooves  60   a-f  and the multipitch optical fiber ribbon  20  (FIG. 1,  2 , and  3 ) is described as including six optical fibers  36  (FIGS.  1 - 3 ), it is within the scope of the present invention for the guide cylinder to include a greater or lesser number of narrow guide grooves and for the multipitch optical fiber ribbon to include a greater or lesser number of optical fibers. 
     In accordance with the first embodiment, a series of marks  64  are defined across the outer surface  56  of the guide cylinder  50 . The series of marks  64  is illustrated and described as including a Roman number I mark, Roman number II mark, Roman number III mark, and Roman number IV mark that designate intervals along the grooves  60   a-f ,  62  in the arcuate direction. The series of marks  64  can incorporate a wide variety of different indicia for designating different intervals along the grooves  60   a-f ,  62 . 
     As will be discussed in greater detail below with reference to FIGS. 7-10, the wide guide groove  62  defines a width “W 3 ”, the narrow guide grooves  60   a-f  define a width “W 4 ”, and each of those grooves define a depth “D”. As best understood with reference to FIG.  4  and FIG. 5, in which the wide guide groove  62  and the narrow guide groove  60   a  are shown by broken lines, the depth of each of the grooves  60   a-f ,  62  is uniform along the length of the groove, except as noted. More specifically, the depths of the narrow guide grooves  60   a-f  taper to zero just past the Roman number IV mark in the direction away from the Roman number III mark. In addition, the depth of the wide guide groove  62  tapers to zero just past the Roman number I mark in the direction away from the Roman number II mark. As illustrated in FIG. 4, the width of each of the grooves  60   a-f ,  62  is uniform along the length thereof. In addition, edges  66  that define the transition between the wide guide groove  62  and the narrow guide grooves  60   a-f  are smooth and slightly rounded to facilitate smooth passage of the optical fibers  36  (FIGS. 1-3) from the wide guide groove to the narrow guide grooves, as will be discussed in greater detail below. 
     FIG. 6 illustrates the fabricating assembly  70  partially set up for fabricating the multipitch optical fiber ribbon  20  (FIG. 1) from a conventional optical fiber ribbon  26  having an exposed array  34  of optical fibers  36  (FIG. 1) extending therefrom, in accordance with the first embodiment. In accordance with one method of the present invention, it is preferred for a portion of the binder material  42  (FIG. 2) to be stripped from an end of an isolated conventional optical fiber ribbon  26  to expose the array  34  of optical fibers  36 , and thereafter for the multipitch optical fiber ribbon  20  to be formed therefrom, as described below. 
     In accordance with the first embodiment, the fabricating assembly  70  includes a frame  72 , which is illustrated by broken lines, that carries the opposite ends of the axle  58  of the guide cylinder  50  (also see FIGS.  4  and  5 ). In accordance with the first embodiment, the frame  72  optionally carries a cross member  74  that is moveable between a remote position that is illustrated by dashed lines and a proximate position that is illustrated by solid lines in FIG.  6 . The cross member  74  is distant from the guide cylindrical  50  while in the remote position. In contrast, the cross member  74  is in close proximity to the apex of the outer surface  56  of the guide cylinder  50  while in the proximate position. Depending upon the rotational position of the guide cylinder  50  about the axle  58 , the cross member  74  can extend laterally across the grooves  60   a-f ,  62  (FIGS. 4 and 5) while in the proximate position, as will be discussed in greater detail below. 
     In accordance with the first embodiment, the frame  72  is moveable and the movability is acceptably facilitated, in part, by a pair of wheels  81  that travel along a track  83 , all of which is illustrated by broken lines in FIG.  6 . More specifically, the frame  72  is movable in a direction between a downstream holding device  88  and an upstream holding device  84 . The upstream holding device  84  is a gripping or clamping device that holds the free end of the exposed array  34  of optical fibers  36 . Preferably the upstream holding device  84  is equipped with a tensioning mechanism  86 , such as a pair of springs, or the like, that maintains a desired tension on the exposed array  34  as it is acted upon, as will be discussed in greater detail below. The downstream holding device  88  is a gripping or clamping device that holds the end of the conventional optical fiber ribbon  26 . 
     In accordance with the first embodiment, a pair of tape application assemblies  76  are positioned on opposite sides of the conventional optical fiber ribbon  26  and are carried by the frame  72 . The tape application assemblies  76  are operative for applying the composite bonding material  44  (FIG. 3) to the exposed array  34  of optical fibers  36 . The tape application assemblies  76  are positioned remotely from the conventional optical fiber ribbon  26  in FIG.  6 . In accordance with the first embodiment, the frame  72  includes mechanisms (not shown) for moving the tape application assemblies  76  from their remote positions illustrated in FIG. 6 to positions in which the tape application assemblies are more proximate to the exposed array  34  of optical fibers  36 . 
     As illustrated in FIG. 6, in accordance with the first embodiment, each tape application assembly  76  acceptably includes a roll  78  of tape and an applicator roller  82 , or the like. For each tape application assembly  76 , the tape  80  is preferably in the form of a tape  46  (FIG.  3 ), such as a conventional water-blocking tape, that is backed on one side with adhesive  48  (FIG.  3 ). In accordance with an alternative embodiment, the adhesive  48  is applied to the exposed array  34  of optical fibers  36  and thereafter the tape  46  is applied to the combination of the adhesive and the exposed array of optical fibers. In accordance with this alternative embodiment, the adhesive can be applied by spraying or other coating techniques. 
     The frame  72 , wheels  81 , and track  83  are illustrated in broken lines in FIG. 6 because in accordance with the first embodiment a variety of different frames and moving mechanisms therefor are suitable for carrying out the movement operations of the present invention. For example, in accordance with one embodiment of the present invention the frame  72 , wheels  81 , and track  83  are not required. As one example, the guide cylinder  50  can be a handheld device that is manually moved along the exposed array  34  of optical fibers  36  and the tape  80  can be manually applied to the exposed array of optical fibers without using the specifically illustrated tape application assemblies  76 . 
     Referring to FIGS. 4 and 6, operations of the fabricating assembly  70  will be described in accordance with the first embodiment. The fabricating assembly  70  is set up for operation by having the cross member  74  in its remote position, which is illustrated by broken lines in FIG. 6, and rotating the guide cylinder  50  about its axle  58  so that the Roman number I mark is at the apex of the outer surface  56  of the guide cylinder. Thereafter, an end of the conventional optical fiber ribbon  26  is connected to the downstream holding device  88  and the exposed array  34  of optical fibers  36  extending from the conventional optical fiber ribbon  26  is connected to the upstream holding device  84  so that the array passes through the portion of the wide guide groove  62  (FIGS. 4 and 5) that is at the apex of the outer surface  56  of the guide cylinder  50 . Then the cross member  74  is moved to its proximate position, at which time the fabricating assembly  70  can be characterized as being in a first configuration. In the first configuration, a portion of the exposed array  34  of optical fibers  36  extends through at least a portion of the wide guide groove  62  and the Roman number I mark is aligned with the cross member. 
     FIG. 7 is a partial, schematic cross-sectional view taken along line A—A of FIG. 6 with the fabricating assembly  70  in the first configuration, in accordance with the first embodiment. As best seen in FIG.  7  and as mentioned above, the wide guide groove  62  defines a width W 3  and a depth D. The width W 3  is slightly greater than the number of optical fibers  36  within the wide guide groove  62  multiplied by the diameter of those optical fibers. The depth D that is slightly greater than the diameter of the optical fibers  36 . Like in the narrow section  26  (FIGS. 1 and 2) of the multipitch optical fiber ribbon  20  (FIGS.  1  and  2 ), approximately the separation spacing S 1  is defined between the centers of the portions of adjacent optical fibers  36  illustrated in FIG.  7 . In accordance with the first embodiment, each of the optical fibers has a diameter of approximately 250 microns, and in FIG. 7 the sides of adjacent optical fibers  36  are abutting one another, so that the separation spacing S 1  is approximately 250 microns. 
     From the viewpoint of FIG. 6, while the fabricating assembly  70  is in the first configuration, which is illustrated in FIG. 7, the spacing between the portions of the optical fibers  36  (FIG. 7) engaged by the guide cylinder  50  can be gradually increased in a consistent and controlled manner by rotating the guide cylinder  50  counterclockwise about its axle  58 . More specifically, the guide cylinder  50  can be rotated counterclockwise about its axle  58 , so that the Roman number II mark, Roman number III mark, or Roman number IV mark (FIG. 4) is aligned with and in contact with the bottom surface of the cross member  74 . As the guide cylinder  50  is rotated counterclockwise, relative motion occurs between the portions of the optical fibers  36  engaged by the guide cylinder  50  and the narrow guide grooves  60   a-f . As will become apparent, the guide grooves  60   a-f  respectively define travel paths, and as the guide cylinder  50  is rotated the optical fibers  36  respectively advance along those travel paths such that the optical fibers become further laterally spaced apart. 
     As best understood with reference to FIGS. 4 and 6, by having the fabricating assembly  70  in the first configuration, which is illustrated in FIG. 7, and then rotating the guide cylinder  50  counterclockwise about its axle  58  so that the Roman number II mark is aligned with and in contact with the bottom surface of the cross member  74 , a second configuration is achieved. The second configuration is characterized by a portion of the exposed array  34  of optical fibers  36  extending through respective portions of the narrow guide grooves  60   a-f  and the Roman number II mark being aligned with the cross member  74 . 
     FIG. 8 is a partial, schematic cross-sectional view taken along line A—A of FIG. 6, with the fabricating assembly  70  in the second configuration. Like in the wide section  30  (FIGS. 1 and 2) of the multipitch optical fiber ribbon  20  (FIG.  1 ), approximately the separation spacing S 2  is defined between the centers of each of the portions of the adjacent optical fibers  36  illustrated in FIG.  8 . Likewise, approximately the separation spacing S 2  is defined between the centers of the portions of each of the adjacent narrow guide grooves  60   a-f  illustrated in FIG.  8 . In accordance with the first embodiment, the separation spacing S 2  is at least approximately twice as great as the separation spacing S 1  (FIGS. 1,  2 , and  7 ), and more specifically the separation spacing S 2  is approximately 500 microns. 
     As best understood with reference to FIGS. 4 and 6, by having the fabricating assembly  70  in the first configuration, which is illustrated in FIG. 7, and then rotating the guide cylinder  50  counterclockwise about its axle  58  so that the Roman number III mark is aligned with and in contact with the bottom surface of the cross member  74 , a third configuration is achieved. The third configuration is characterized by a portion of the exposed array  34  of optical fibers  36  extending through respective portions of the narrow guide grooves  60   a-f  and the Roman number III mark being aligned with the cross member  74 . 
     FIG. 9 is a partial, schematic cross-sectional view taken along line A—A of FIG. 6, with the fabricating assembly  70  in the third configuration. A separation spacing “S 3 ” is defined between the centers of each of the portions of the adjacent optical fibers  36  illustrated in FIG.  9 . Likewise, approximately the separation spacing S 3  is defined between the centers of each of the portions of the adjacent narrow guide grooves  60   a-f  illustrated in FIG.  9 . In accordance with the first embodiment, the separation spacing S 3  is at least approximately three times greater than the separation spacing S 1  (FIGS. 1,  2 , and  7 ), and more specifically the separation spacing S 3  is approximately 750 microns. 
     As best understood with reference to FIGS. 4 and 6, by having the fabricating assembly  70  in the first configuration, which is illustrated in FIG. 7, and then rotating the guide cylinder  50  counterclockwise about its axle  58  so that the Roman number IV mark is aligned with and in contact with the bottom surface of the cross member  74 , a fourth configuration is achieved. The fourth configuration is characterized by a portion of the exposed array  34  of optical fibers  36  extending through respective portions of the narrow guide grooves  60   a-f  and the Roman number IV mark being aligned with the cross member  74 . 
     FIG. 10 is a partial, schematic cross-sectional view taken along line A—A of FIG. 6, with the fabricating assembly  70  in the fourth configuration. A separation spacing “S 4 ” is defined between the centers of each of the portions of the adjacent optical fibers  36  illustrated in FIG.  10 . Likewise, approximately the separation spacing S 4  is defined between the centers of each of the portions of the adjacent narrow guide grooves  60   a-f  illustrated in FIG.  9 . In accordance with the first embodiment, the separation spacing S 4  is at least approximately four times greater than the separation spacing S 1  (FIGS. 1,  2 , and  7 ), and more specifically the separation spacing S 4  is approximately 1000 microns. 
     As best seen in FIGS. 8-10 and as mentioned above, each of the narrow guide grooves  60   a-f  defines a width W 4  and the above-discussed depth D. The width W 4  is slightly greater than the diameter of the optical fibers  36 . 
     In accordance with the first embodiment, in each of the first through fourth configurations respectively illustrated by FIGS. 7-10, the optical fibers  36  extend in a plane that is approximately tangent to the innermost surfaces of the guide cylinder  50  that define the respective groove(s)  60   a-f ,  62  so that only small arcuate lengths of the respective groove(s) are occupied at any time by the optical fibers  36 . Accordingly, in each of the second through fourth configurations respectively illustrated by FIGS. 8-10, only a small arcuate length of each of the narrow guide grooves  60   a-f  is occupied at any time by its respective optical fiber  36 , and each of those small arcuate lengths can be characterized as an active portion or a spacing guide portion. As best seen in FIGS. 8-10, the cross member  74  cooperates with the spacing guide portions to define what can be characterized as spacing apertures through which the optical fibers  36  respectively extend. The spacing guide portions and spacing apertures move laterally with respect to one another as the guide cylinder  50  is rotated, as is best understood with reference to FIGS. 7-10, which sequentially illustrate rotational positions of the guide cylinder. 
     As best understood with reference to FIGS.  4  and  7 - 10 , the rate at which the narrow guide grooves  60   a-f  transition from the separation spacing S 1  to the separation spacing S 2 , from the separation spacing S 2  to the separation spacing S 3 , and from the separation spacing S 3  to the separation spacing S 4  is preferably sufficiently gradual so as not to cause the optical fibers  36  to be damaged by stress and strain when the optical fibers  36  are moved between the first through fourth configurations. 
     As best understood with reference to FIGS.  6  and  8 - 10 , the fabricating assembly  70  is set up for operation by establishing the desired spacing between the optical fiber ribbons  36 , which is achieved by placing the fabricating assembly  70  in the second configuration (FIG.  8 ), the third configuration (FIG.  9 ), or the third configuration (FIG.  9 ), or in any of the other numerous configurations that are between the first configuration (FIG. 7) and the fourth configuration. Thereafter, the guide cylinder  50  is preferably locked with a locking mechanism (not shown) so that the guide cylinder will not rotate relative to the cross member  74 . As best seen in FIG. 11, in accordance with the first embodiment, the tape application assemblies  76  are placed in their proximate positions by moving them toward one another so that the applicator rollers  82  force the adhesive sides of the tape  80  onto or immediately adjacent to the opposite sides of the narrow end  29  (FIG. 1) of the conventional multipitch optical fiber ribbon  26 . 
     After the fabricating assembly  70  is fully set up for operation as described above, the exposed array  34  of optical fibers  36  is advanced through the respective spacing guide portions of the narrow guide grooves  60   a-f . As mentioned above, in each of the second through fourth configurations respectively illustrated by FIGS. 8-10, only a small arcuate length of each of the narrow guide grooves  60   a-f  is occupied at any time by the respective one of the optical fibers  36 , and each of those small arcuate lengths can be characterized as an active portion or a spacing guide portion. In accordance with the first embodiment, the advancing is achieved by moving the guide cylinder  50  relative to the optical fibers  36 , and preferably that movement is translational. More specifically, the advancing is achieved by moving the frame  72  along the track  83 , as illustrated in FIG.  11 . The frame  72  is one example of a moving device for advancing the optical fibers  36  in the longitudinal direction through their respective spacing guide portions of the guide grooves  60   a-f  so that the spacing of the spacing guide portions is imparted upon portions of the optical fibers that are downstream from the guide cylinder  50 . 
     As best seen in FIG. 11, as the frame  72  moves toward the upstream holding device  84 , the pieces of tape  80  are longitudinally applied to the opposite sides of the exposed array  34  of optical fibers  36  that are downstream from the guide cylinder  50  to form the wide section  30  of the multipitch optical fiber ribbon  20 . Alternatively, one or more pieces of the tape  80  may be helically wrapped around the exposed array  34  of optical fibers  36  that are downstream from the guide cylinder  50  to form the wide section  30  of the multipitch optical fiber ribbon  20 . The formed multipitch optical fiber ribbon  20  is removed from the fabrication assembly  70  by releasing the narrow section  26  from the downstream holding device  88 , releasing the array  34  of optical fibers  36  from the upstream holding device  84 , and moving the cross member  74  to its remote position, which is illustrated by broken lines in FIG.  6 . 
     In accordance with the first embodiment, the wide section  30  of the multipitch optical fiber ribbon  20  has the separation spacing S 2  (FIGS. 1,  3 , and  8 ). Accordingly, in accordance with the first embodiment, when the fabricating assembly  70  is fully set up for operation it is in the second configuration, which is illustrated in FIG.  8 . 
     A multipitch optical fiber ribbon of a second embodiment of the present invention is like the multipitch optical fiber ribbon  20  (FIG. 1) of the first embodiment, except that in the second embodiment the separation spacing S 3  (FIG. 9) is defined between the optical fibers in the wide section (for example see the wide section  30  in FIGS. 1 and 3) of the multipitch optical fiber ribbon, and the wide section defines a greater width than the width W 2  (FIG.  1 ). In accordance with the, second embodiment, when the fabricating assembly  70  is fully set up for operation it, is in the third configuration, which is illustrated in FIG.  9 . 
     A multipitch optical fiber ribbon of a third embodiment of the present invention is like the multipitch optical fiber ribbon  20  (FIG. 1) of the first embodiment, except that in the third embodiment the separation spacing S 4  (FIG. 10) is defined between the optical fibers in the wide section (for example see the wide section  30  in FIGS. 1 and 3) of the multipitch optical fiber ribbon, and the wide section defines a greater width than the width W 2  (FIG.  1 ). In accordance with the third embodiment, when the fabricating assembly  70  is fully set up for operation it is in the fourth configuration, which is illustrated in FIG.  10 . 
     As best understood with reference to FIGS. 1-3, in accordance with a fourth embodiment of the present invention, homogenous bonding material  42  is substituted for the composite bonding material  44  of the wide section  30  of the multipitch optical fiber ribbon  20 . In accordance with the fourth embodiment, the tape application assemblies  76  illustrated in FIGS. 6 and 11 are replaced with conventional assemblies for applying the homogenous bonding material  42 . 
     As best understood with reference to FIG. 11, in accordance with a fifth embodiment of the present invention, the frame  72  of the fabricating assembly  70  is stationery, and the exposed array  34  of optical fiber ribbons  36  are drawn past the guide cylinder  50  during the formation of the wide section  30  of the multipitch optical fiber ribbon  20 . This is acceptably achieved by paying the exposed array  34  of optical fiber ribbons  36  off of an upstream supply roll (not shown) and wrapping the formed multipitch optical fiber ribbon  20  onto a downstream take up roll (not shown). 
     Whereas the present invention is described above in the context of forming the multipitch optical fiber ribbon  20  from a previously formed conventional multipitch optical fiber ribbon  26 , it is within the scope of the present invention for the fabricating assembly  70  to be used to construct a multipitch optical fiber ribbon or a single-pitch optical fiber ribbon from an array of optical fibers that were not previously associated with an optical fiber ribbon, as should be understood by those of ordinary skill in the art in view of this disclosure. 
     Many other modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.