Abstract:
A fiber optic cable connector device capable of coupling fiber optic cables for use in installing a fiber optic cable network including a cap member having an for receiving and securing a fiber optic cable end portion, a sleeve member having a retaining device to receive, engage and secure the cap member containing a fiber optic cable end portion, and a coupling member having a retaining device to receive, engage and secure the assembled fiber optic cable end portion, sleeve and cap members. An adapter, having fiber conduit slidably mounted within a support member housing, provides an interface for coupling multiple single-fiber carrying fiber optic cables and dual fiber carrying fiber optic cables. A method of terminating fiber optic ends with little or no polishing incorporates viewing the illuminated fiber end-face through a microscope.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a new and improved method and apparatus for installing fiber optic cables. More particularly, the invention relates to an inventive method of aligning fibers and fiber end-faces to eliminate the need for polishing, and inventive improvements in fiber optic cable components, such as adapters, connectors, coupling assemblies and pull protectors, to provide high quality termination of fiber optic cables and ease of cable installation in the field.  
           [0003]    2. Description of Related Art Including Information Disclosed under 37 CFR 1.97 and 37 CFR 1.98  
           [0004]    Typically, fiber optic cables installed in or between buildings to enable intra-organizational data and telephone communications are housed in conduits and connected with de-matable connectors. The benefits of fiber optics for use in these local networks are many. However, the primary benefit lies in the ability to send the information of many telecommunication instruments over an exceedingly small number of channels as compared to conventional copper cables. A single pair of optical fibers may, in fact, replace several hundred pairs of copper cables.  
           [0005]    Fiber optic cables are desirable because of a need for high capacity small cables, especially where conventional copper or coaxial cables of equivalent capacity will not fit, e.g., in small or congested cable ducts. Copper or coaxial cable bundles as large as 100 mm in diameter can be avoided in favor of fiber optic cables as small as 3 mm in diameter.  
           [0006]    However, single channel de-matable fiber optic connectors which are used to terminate the cable are typically 8 to 20 millimeters in diameter. This results in a connector bundles having diameters much larger then the cable diameters. For example, a typical AT&amp;T Technologies connector used to terminate a typical 6 channel, 8 mm diameter, fiber optic cable will result in a bundle size of 36.7 mm, which is over four (4) times the size of the cable. The National Electrical Code limits a single cable to 53% of the conduit area. Thus, the 8-mm cable can easily fit a standard ½-inch conduit. The same cable with pre-installed connectors would require a 1½inch standard conduit just to clear the connector bundle. Pulling equipment may dictate an even larger size conduit. Furthermore, the existence of previously installed cable and/or a series of 90-degree conduit bends might raise the required conduit size even higher. To compound these problems, the typical cable grip used to install cables in conduits does not expand to a size greater than a small percentage larger than the minimum allowable cable diameter, i.e., it will not fit over a connector bundle with a diameter greater than a small percentage larger than the diameter of the cable. Recently new plastic pull protectors have been developed, which allow the pull of larger bundles. However, these larger bundles cannot be pulled through most electrical ducts because of their larger diameter.  
           [0007]    This situation has almost universally resulted in field termination (as opposed to the more desirable factory termination) of duct-installed fiber optic cables. Installing the typical epoxy and polish connector is time-consuming, and takes approximately 20 to 40 minutes per end (two ends per connection) requiring approximately 40 separate steps. For example, some of these required steps include: (1) stripping the jacket away from the cable; (2) folding back the kevlar material and stripping the buffer material; (3) cleaving or putting a break in the fiber such that the break is perpendicular to the axis of the fiber; (4) cementing the fiber inside of the connector with epoxy; and (5) polishing the fiber optic connector. The connectors may each cost as much as $10.00 or more. An incorrect installation or accidental breakage of the fragile fiber may necessitate that the connector be cut off, discarded and a new installation procedure begun, necessitating repeating all of the tedious steps, including that of polishing the connector, which is perhaps the most time-consuming. As a result, highly skilled personnel are typically required to perform field installation of de-matable connectors.  
           [0008]    My U.S. Pat. No. 5,253,315, addressed this issue by disclosing a universal connector body provided with the capability of mating with most existing connectors on the market. A universal inner housing is provided which mates with a wide variety of coupling nut assemblies or adapters, allowing these coupling nut assemblies or adapters to mate with the universal connector body. The connector body design has the fiber terminated to a precision tip, which is spring-loaded within the housing to which the strength member is terminated to prevent interruption of the optical signal if the cable is pulled or otherwise disturbed. This design also provides for the take-up of slack buffered fiber due to the retraction of the spring-loaded tip. The manner in which the universal connector body mates with the universal inner housing provides a method of indexing the rotation of the connector body, allowing it to be tuned as to insertion loss upon installation or thereafter. The inner housing is compatible with a wide variety of connector adapters, including ST, SC, FC, D4, and high-density types.  
           [0009]    The termination of the connector body to an optical fiber is facilitated by its unique design, which greatly simplifies the process as compared to conventional pull-proof connectors. The connector body may be terminated for pulling through a building duct by employing a unique process and a special pull boot described in this patent.  
           [0010]    However, certain aspects of my disclosure U.S. Pat. No. 5,253,315 may be improved upon. The method of interchanging the coupling nut assemblies or adapters requires a special tool. The assembly of the universal connector body does not lend itself well to the incorporation of 900 um cable designs, and the pull protector requires a complicated housing.  
           [0011]    Accordingly, I have invented a new and improved universal connector body, adapter and pull protector method which provides for the interchange of adapters without a tool, facilitates the incorporation of 900 um cable designs, and provides a simplified and pull protector that is relatively easier to use.  
           [0012]    When attaching fiber optic cables to communications systems it is necessary to terminate them with fiber optic connectors. Fiber optic connectors position the fiber ends of the fiber optic cable to receive or transmit light. The surfaces of the fiber ends must be smooth and perpendicular to the fiber axis for greatest efficiency in accepting light rays. In addition, for low-loss terminations, care must be taken to preserve the domed profile of the connector ferrule or prepare the fiber such that is has a slight protrusion. Rough or dirty end surfaces block and scatter light.  
           [0013]    The conventional method of terminating an optical fiber involves the application of epoxy and polishing with a variety of grinding papers and solutions. The objective is to polish the optical fiber end-face flat and smooth, while preserving the domed profile of the connector ferrule. This glue and polish practice is wide-spread, although it has been found to provide acceptable results, such results vary depending upon the skill of the operator.  
           [0014]    The typical steps of the conventional means to terminate fiber optic connectors onto a fiber optic cable include approximately 43 steps as follows:  
           [0015]    Gather all materials (fiber cable, connectors, epoxy, syringes, polishing film, fiber disposal bin, and toolbox);  
           [0016]    Place everything on the table in a convenient location;  
           [0017]    Open connector package and lay-out all parts. Do not take dust cap off the connector ferrule yet;  
           [0018]    Prepare the cable;  
           [0019]    Push rubber strain relief boot about 4 inches up the cable;  
           [0020]    Push the crimp ring up the cable to the boot (make sure it is on in the right direction);  
           [0021]    Strip a length of jacket from the fiber, depending upon the specific connector type;  
           [0022]    Cut the kevlar to some length depending upon the specific connector type;  
           [0023]    Strip the buffer ¼″ at a time until some length of fiber is exposed, depending upon the specific connector type;  
           [0024]    Clean the fiber;  
           [0025]    Prepare epoxy;  
           [0026]    Place needle on syringe to receive the epoxy;  
           [0027]    Mix epoxy;  
           [0028]    Pour into syringe;  
           [0029]    Replace plunger;  
           [0030]    Hold upright and slowly get air out of syringe;  
           [0031]    Select connector;  
           [0032]    Remove dust cap from connector;  
           [0033]    Push syringe all the way into connector;  
           [0034]    Push in plunger to inject epoxy until a bead appears on the end of the ferrule of the connector;  
           [0035]    Pull the syringe halfway out of the connector and fill the backshell with epoxy carefully;  
           [0036]    Insert the fiber into the connector and carefully work it through the ferrule, twisting the connector as you go, until the fiber is in as far as possible;  
           [0037]    Insure that you have a good-sized bead of epoxy on the tip of the ferrule;  
           [0038]    Push the crimp sleeve up, capture the kevlar and crimp it to the back-shell of the connector;  
           [0039]    Crimp the back of the crimp sleeve to the cable;  
           [0040]    Push the boot over the crimp sleeve;  
           [0041]    Wipe off excess epoxy from the protruding fiber. Be careful not break off the fiber or remove the epoxy bead at the tip of the ferrule. Fiber breakage at this point could make connector unusable;  
           [0042]    Cure the epoxy. Cure only until the bead of epoxy is hardened. The epoxy inside the ferrule will cure fully at room temperature in less than 24 hrs;  
           [0043]    Cleave and polish using the following steps: Gather up tools and supplies, set up polishing plate with 3 and 0.3 micron lapping film (the connector is ready for cleaving and polishing when the epoxy bead on the tip is hardened), cleave the fiber, using  15 micron film, “Air Polish” to remove most of the protruding fiber and epoxy bead, and air polish with 12 micron film to remove burr and most of the epoxy bead;  
           [0044]    Put connector in polishing puck;  
           [0045]    Lay gently on 3 micron film;  
           [0046]    Polish with a FIG. 8 motion until epoxy bead is gone and it gets “slippery”;  
           [0047]    Wipe off;  
           [0048]    Polish a few figure “8&#39;s” on 3 micron film;  
           [0049]    Clean;  
           [0050]    Test;  
           [0051]    View in microscope; and  
           [0052]    Test for loss.  
           [0053]    These steps must be carefully followed and checked by experienced persons in order to achieve acceptable results. An alternative to this 43-step termination method is to use less durable termination processes with lower environmental performance. Alternatively, much more expensive connectors can be used which may eliminate some of these termination steps.  
           [0054]    There exists a need to improve this method cheaply and efficiently, in that regard, I have invented an apparatus and method for the termination of optical fiber connectors with little or no polishing. This device and method produces consistent, low-loss terminations with considerably less effort that the 43-step method and using conventional inexpensive connectors. Also, this device and method preserves the domed profile of the connector ferrule and enables preparation of the fiber such that is has a slight protrusion if desired. Furthermore, this device and method has been found to yield the best fiber contact between mating connectors and, therefore, the lowest loss and back reflection.  
         SUMMARY OF THE INVENTION  
         [0055]    A new and improved apparatus and method for installing fiber optic cables, resolving the deficiencies of past systems, is disclosed herein. The inventive system serves to simplify the process of installing fiber optic cables and reduce the associated installation and equipment costs.  
           [0056]    The inventive components comprise a new and improved universal connector body capable of securing a fiber optic cable and being mated with a new and improved coupling nut assembly or new and improved adapter. The universal connector body has an inventive retaining device to capture and secure receiving devices on the coupling nut assembly or adapter. The inventive components are also suitable for mating with existing connectors on the market.  
           [0057]    The present invention also provides for capturing and securing a spring-loaded cap or ferrule assembly within the inventive universal connector body housing, which may then be captured and secured in an inventive coupling nut assembly, thus preventing separation of the terminated ends of fiber within the components.  
           [0058]    The present invention further provides a new and improved pull-protector apparatus for protecting one or more pre-terminated universal connector bodies while being pulled through a duct or conduit during installation of a communications system.  
           [0059]    The present invention further provides a new and improved apparatus and method for aligning the fiber optic connector end-face while terminating the fibers. An inventive positioning apparatus and method provides a view of the precise location of the fiber optic fiber with respect to the fiber optic connector end-face, thus enabling a technician to properly align the fiber optic fibers in the fiber optic connector while cementing material is setting. The resulting termination is characterized by optimal positioning of the fiber and a very low insertion loss and back reflection, thus minimizing or even eliminating the time-consuming step of polishing connector end-faces for both multimode and single-mode terminations.  
           [0060]    An inventive adapter for adapting different connector and fiber optic cable formats. In particular, the inventive adapter is useful for connecting the 2.5 mm diameter type, characteristic of the ST, FC and SC connector interfaces or other connector types, to duplex connector formats with closely-spaced fibers, like the 0.75 millimeter fiber separation of the MT-RJ connector or other industry standard fiber optic simplex and duplex connectors. The inventive adapter allows for immediate interfacing of other connector formats to duplex fiber optic connectors with closely-spaced fibers without employing expensive jumper cables. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0061]    [0061]FIG. 1 is a diagram useful to explain the assembly process showing the ferrule assembly being captured by the new and improved universal connector body housing, which in turn, is sliding into a new and improved coupling nut assembly or adapter;  
         [0062]    [0062]FIG. 2 is a cross-section of a fiber optic cable with a fiber stripped and prepared for termination to the ferrule assembly of the present invention;  
         [0063]    [0063]FIG. 3 is a cross-section of the ferrule and universal connector body housing with a fiber optic cable in place, prior to the ferrule and universal connector body housing being engaged;  
         [0064]    [0064]FIG. 4 is a top view of the ferrule and universal connector body housing with a fiber optic cable in place, after the ferrule and universal connector body housing have been engaged;  
         [0065]    [0065]FIG. 5 is a cross-section of the inventive pull-protector, showing the attachment of two terminated ferrule and universal connector body housing assemblies with the pull-protector;  
         [0066]    [0066]FIG. 6 is a cross-section of the inventive pull-protector of FIG. 5, illustrating the configuration of the two terminated ferrule and universal connector body housing assemblies while attached to and being pulled by the inventive pull-protector;  
         [0067]    [0067]FIG. 7 is a cross-section of a terminated ferrule and universal connector body housing assembly and inventive coupling nut assembly, prior to the engagement of the ferrule and connector assembly;  
         [0068]    [0068]FIG. 8 is a cross-section of the terminated ferrule and universal connector body housing assembly and inventive coupling nut assembly of FIG. 7, after engagement of the ferrule and universal connector body housing assembly;  
         [0069]    [0069]FIG. 9 is a diagram useful to explain the assembly process of a second embodiment of the present invention, in which a ferrule assembly is captured by an alternative method and alternative embodiment of the inventive universal connector body housing;  
         [0070]    [0070]FIG. 10 is a cross-section of the ferrule and fiber optic cable of the present invention being terminated onto a stripped fiber optic cable in accordance with the alternative method;  
         [0071]    [0071]FIG. 11 is a cross-section of the ferrule and universal connector body housing assembly with a fiber optic cable in place, after the assembly has been engaged, in accordance with the second embodiment illustrated in FIG. 9;  
         [0072]    [0072]FIG. 12 illustrates the attachment of the two terminated ferrule and universal connector body housing assemblies of FIG. 9 with the inventive pull-protector;  
         [0073]    [0073]FIG. 13 illustrates the configuration of the two terminated ferrule and universal connector body housing assemblies of FIG. 9 while attached to and being pulled by the pull-protector;  
         [0074]    [0074]FIG. 14 is a cross-section of the terminated ferrule and universal connector body housing assembly in accordance with the second embodiment, and inventive coupling nut assembly, prior to the engagement of the ferrule and universal connector body housing assembly;  
         [0075]    [0075]FIG. 15 is a cross-section of the terminated ferrule and universal connector body housing assembly in accordance with the second embodiment, and inventive coupling nut assembly, after the engagement of the ferrule and universal connector body housing assembly;  
         [0076]    [0076]FIG. 16 is an illustration useful for explaining the inventive termination method of optical fiber connectors with little or no polishing;  
         [0077]    [0077]FIG. 17 is an illustration useful for explaining the viewing procedure for determining the fiber end-face position relative to the connector ferrule end-face and fiber protrusion δ; and  
         [0078]    [0078]FIG. 18 illustrates the inventive adapter and method for use with the disclosed inventive components or other standard fiber optic formats. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0079]    Reference is made to FIGS.  1 - 18  of the drawings in detail, which show the assembly and installation procedure for the new and improved universal connector body.  
         [0080]    Referring to FIG. 1, fiber  10  from fiber optic cable  12  is inserted through universal connector body housing  14 , and engaged by a ferrule  16  having a hollow ceramic tip  18 . A spring  20  is disposed over a length of hollow tube  22  having a protruding member  24  proximate to opening  26  in the hollow tube  22 . Protruding member  24  secures spring  20  on tube  22 , and functions to connect the body housing  14 , as will be discussed below.  
         [0081]    Ferrule  16  is connected with connector body housing  14  by a retaining device. In this embodiment, the retaining device comprises inserting protruding member  24  into gripping device  28  on a universal connector body housing  14 , as illustrated in FIG. 4. Gripping device  28  has ramps  29  which are slanted to allow member  24  to be easily inserted into and locked into position but not easily removed from opening  31 . Opening  3 lis configured to engage member  24  upon its insertion.  
         [0082]    [0082]FIG. 3 illustrates fiber  10  inserted through ferrule  16  and connector body housing  14  just prior to member  24  being engaged by gripping device  28  and kevlar ends  30  being set through opening  34 . The universal connector body housing  14  is installed over the fiber optic cable  12  before the termination process. Ripped open and pulled away kevlar sheath ends  30  surround fiber  10  and are pulled away from cable  12  after fiber  10  and kevlar  30  is inserted through ferrule assembly  16 . Cable  12  also has an exterior casing  13 , which is typically made of PVC or plastic material. FIG. 2 illustrates fiber optic cable  12  being stripped of casing  13  to expose kevlar  30  and fiber  10 . When cable  12  is passed through connector body housing  14  and retaining device  29  is engaged, ferrule  16  is secured to housing  14 . Separated kevlar ends  30  are slipped through opening  31  into slot  32  and finally into opening  34 . Opening  34 , slot  32  and opening  31  are cut in universal connector body housing  14 . Kevlar ends  30  are exposed to a sufficient length to enable their attachment to a pull protector  36 .  
         [0083]    As shown in FIG. 4, the kevlar ends  30  and universal connector body housing  14  may be fixed to cable  12  by using an adapter tube  37 , which is placed over cable  12  before cable  12  is connected to ferrule  16 . Adapter  37  has an end configured to engage housing  14  and an opposing end configured to engage cable  12 . Preferably, adapter tube  37  is filled with adhesive prior to it being installed on housing  14  and cable  12 . A latch  38  (FIG. 3) on universal connector body housing  14  secures housing  14  on coupling nut assembly  40  as shown, or an adapter, by engaging slot  42  (FIG. 1) in receiving tube  44  on coupling nut  40 , as shown in FIG. 1. Housing  14  would be installed in coupling nut  40  once the fiber  10 , ferrule  16  and housing  14  are assembled together.  
         [0084]    Kevlar ends  30  may also be attached to pull-protector  36  in the manner shown in FIG. 5. Pull-protector  36  consists of a central cylinder  46  sufficiently large enough to contain at least one pre-terminated universal connector housing  14 . Preferably, cylinder  46  is sufficiently large enough to contain several pre-terminated universal connector housing bodies. Central cylinder  46  has a closed end  48  with an opening  50 , an open end  51  for receiving the pre-terminated universal connector housings  14  and a pair of opposing cylinder side openings  52 . Kevlar ends  30  of two universal fiber optic cable assemblies  54  are fixed together at  56  by any conventional means, thus forming a first loop  53 . Rope  58  is threaded from the inside of cylinder  46  through opening  50  and fixed by a knot  60  or epoxy drop to form a loop  55  on the outside of closed end  48  and prevent it from slipping back through opening  50 . The ends of rope  58  are threaded through side openings  52  and then fixed around the first loop  53  by knot  62 , an epoxy drop, or similar artifice. Thus, pulling on rope  58  while holding cylinder  46  in place results in pulling the first loop and the universal cable assemblies  54  into the cylinder but not beyond the point at which side openings  52  are located, as illustrated in FIG. 6. This procedure protects the universal fiber optic cable assemblies  54  while installation is being completed by the cable being pulled through a pipe or other conduit with the pull-protector protecting the forward end of the cable while it is being pulled forward, after which the pull-protector is removed.  
         [0085]    Once the universal fiber optic cable assembly  54  is terminated, for example, after having been installed in a communication duct or tray, kevlar ends  30  that were attached to the pulling rope  58  of the pull-protector  36  are cut and the assembly  54  is inserted into coupling nut assembly  40 , as illustrated in FIGS. 7 and 8. Upon insertion, latch  38  engages slot  42  to keep assembly  54  within coupling nut  40 . Assembly  54  may then be removed by depressing latch  38  while pulling assembly  54  from coupling nut  40 . Coupling nut  40  comprises hollowed out tube  64  and spring  66  within housing  68 . Tube  64  has an opening at one end configured to engage assembly  54  and an opening at the other end configured to engage ceramic tip  18 .  
         [0086]    FIGS.  9 - 15  illustrate an alternative embodiment of the universal connector body  114  and retaining device. In this second embodiment, universal connector body housing  114  has a longitudinal groove  132  connected to two slots  131  and  134  cut out in housing  114 . Slot  134  receives kevlar ends  130  from fiber optic cable  112 . As shown in FIG. 11, one or more of the kevlar ends  130  is reserved for attaching to pull-protector  136 . The second segment  44  is brought out of the new and improved universal connector body housing through slot  38  and captured on the rear of the Ferrule  116  is connected to cable  112  before being inserted into housing  114 , as illustrated in FIG. 10. Retaining member  122  is a separate part which is inserted into universal connector body housing  114  to retain ferrule  116 , by sliding tab  170  through groove  132  into engagement with slot  131 . Member  122  has a beveled bottom  172 , which permits it to be depressed inside of universal connector body housing  114  by pushing down on tab  170 , thus enabling tab  170  to be inserted into tube  144  of coupling nut  140  as shown, or an adapter, and engaged with opening  142 . After engagement, the lower step  174  of tab  170  is used to fill slot  131  and opening  142  to further secure the assembly and prevent relative motion between parts, as illustrated in FIG. 15. The beveled bottom  172  maintains tab  170  in a substantially upright position within slot  131  and opening  142 , when not being forcibly depressed, as illustrated by arrow  176  in FIG. 14.  
         [0087]    FIGS.  16 - 17  illustrate the method and apparatus for termination of a fiber optic cable with little or no polishing in detail. An optical fiber  210  is cleaved perpendicular to its axis to within one degree. Fiber  210  is inserted into an optical fiber connector  212  filled with a curing adhesive. The optical fiber connector  212 , with fiber  210  inserted, is positioned in a termination mechanism consisting of a holder  216  (which may be the user&#39;s hand) for fiber optic connector  212 , a fiber positioning device  214 , a microscope  218  for viewing fiber  210 , and a lamp  220  for illuminating the end of ferrule  222  and fiber  210 .  
         [0088]    Holder  216  for fiber optic connector  212  keeps connector  212  secured so that stable viewing of the protrusion of the fiber  210  in the ferrule  222  is possible. The microscope  218  for viewing fiber  210  and lamp  220  for illuminating the end-face of fiber  210  and ferrule  222  are positioned on opposite sides of fiber  210  and ferrule  222 , but at the same angle φ with respect to plane  224  of the fiber end-face. This geometric arrangement of microscope  218  and lamp  220  permits the lamp light to reflect into microscope  218 , thus providing brilliant illumination of the position of fiber  210  with respect to the ferrule end-face. Then, using fiber-positioning device  214 , fiber  210  may be adjusted to a perfect, slightly protruded, position before the adhesive is cured. Also, the fiber end-face protrusion relative to the connector ferrule δ may be determined by comparing shadow  226  cast by lamp  220  to a graticule etched on the optics of microscope  218 , as illustrated in FIG. 17.  
         [0089]    Reference is now made to FIG. 18, which illustrates an adapter  310 , which may be used with the inventive universal housing  14  or  114 , for mating fiber optic cables and components. Adapter  310  comprises a fiber carrier or conduit  312  inside a housing  314 . Fiber optics channels  316  and  318  which permit light to travel through adapter  310  are contained within conduit  312 . Conduit  312  spans housing  314 , having two ends  332  and  334 . Fiber optics channels  316  and  318  terminate in duplex connector interface  324  near end  332 , and extend separately and terminate in two ferrule legs  320  and  322  near end  334 , thus creating spaces  336 ,  337  and  338  in conduit  312  within housing  314 . Spaces  336 ,  337  and  338  have coupling and retaining devices for securely mating components within housing  314 . The coupling and retaining devices may be any conventional device, such as a snap-fitting engagement or retaining devices previously discussed and illustrated in FIGS. 1 and 9, that is, such as the latch  38  or tab  170  and corresponding slots  42  and  142 , respectively. Spaces  336 ,  337  and  338  also allow conduit  312  to slide longitudinally within housing  314  to protect ferrule legs  320  and  322  and duplex fiber optic connector interface  324  from the force applied when mating adapter  310  with other components.  
         [0090]    A duplex connector  326 , connected to a duplex or multi-channel fiber optic cable  344  having fibers  350 , is inserted into housing  314  to connect with interface  324 . Thus, when connector  326  is mated with interface  324 , light from fiber optic channels  316  and  318  is able to travel through connector  326  and into fibers  350  of cable  344 .  
         [0091]    Generic coupling sleeves  340  and  342  of two single-channel fiber optic connectors  328  and  330 , respectively, are inserted into conduit  312  at end  334  to connect with legs  320  and  322 , thus permitting light to travel through fiber channels  316  and  318  into cables  346  and  348 . Ferrules  320  and  322  are sufficiently spaced to allow proper mating with individual single channel fiber optic connectors  328  and  330 .  
         [0092]    Fibers  316  and  318  are polished or otherwise suitably prepared so as to enable a low-loss connection at points  352  and  354  and at interface  324 . The polishing process enables the light traveling in the fibers of one connector to pass, with low attenuation, to the fibers of the mating connector. Typically, manufacturers of duplex connectors employ close spacing of fibers to enable the duplex connector to maintain a compact width and height.  
         [0093]    Adapter  310  may also be configured for alternative formats of fiber cables, such as the 0.75 millimeter fiber separation characteristic of the MT-RJ connector interface. Ferrules  320  and  322  may be of the simplex 2.5 mm diameter type, which is characteristic of the ST, FC and SC connector interfaces and other connector types. Furthermore, adapter  310  may also be connected to the universal fiber optic connector of U.S. Pat. Nos. 4,711,517 and 5,253,315 and to the MT-RJ connector without employing expensive jumper cables.  
         [0094]    While illustrative embodiments of the invention have been described above, it is, of course, understood that various modifications will be apparent to those of ordinary skill in the art. Many such modifications are contemplated as being within the spirit and scope of the invention.