Patent Publication Number: US-7585116-B2

Title: Fiber optic connector having hermaphroditic coupling mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 11/734,658, filed Apr. 12, 2007, entitled FIBER OPTIC CONNECTOR HAVING HERMAPHRODITIC COUPLING MECHANISM, which is incorporated herein by reference. 

   TECHNICAL FIELD 
   The disclosure relates to fiber optic connectors and in particular, to a hermaphroditic coupling mechanism for such connectors. 
   BACKGROUND OF THE INVENTION 
   Hermaphroditic couplers for fiber optic cable must incorporate features that allow the coupler to perform as either a female or male plug such that identical connectors may be coupled to each other. Known hermaphroditic couplers utilize either a conventional threaded configuration wherein a coupling nut moves to a rearward or forward position or a bayonet configuration. The drawback to the threaded connection is that the coupling nut must be rotated through a number of turns to mate with the opposing connector. 
   Bayonet type connectors are known that use a pin or pins extending inward from a fixed coupling nut. The pins engage J-shaped grooves, one in the first connector body, the second in the mating connector body. The pins engage and slide through the long leg of the J-shaped groove then through the crook of the J and into the short leg or locking recess of the J-shaped groove to prevent the coupling nut from inadvertently loosening. In the case of a plug connecting to a plug, there may be four pins, two of which engage each of the connectors to provide a secure connection. In the case of a panel mounted receptacle, which does not include a coupling nut, there are only two pins, only one of which engages the receptacle. 
   There are two drawbacks to conventional bayonet connectors, the first being the movement of the connector faces as the pins move into the locking recess or short leg of the J-shaped groove. Typically the connector faces mate tightly together at the point where the pins are at the endmost tip of the crook of the J-shaped grooves. As the pins move through the crook and into the locking recess, the mating faces tend to move apart. Thus, the depth of the short leg of the J-shaped groove translates into a space between connector faces that may allow angular movement of the connectors relative to each other. 
   The second drawback of conventional bayonet type connectors is that when the plug is mated into a panel mounted receptacle, only one of the bayonet pins engages the receptacle. In this configuration, only one side of the plug is secured. A normal force applied to the plug may result in angular movement of the plug relative to the receptacle. In the case of fiber optic cables, such movement can result in the terminal ends of the cables being displaced from each other, interfering with or cutting off the transmission carried by the cable. 
   The magnitude of these problems is increased in the case of single mode cables. Multi-mode cables have a core with a nominal diameter from about 50 to 100 microns, typically on the order of 62.5 microns. Alternatively, single mode cables have a core with a nominal diameter of 8-10 microns, typically on the order of 9 microns. Single mode cables are capable of greater transmission speed over longer distances with less signal attenuation; however, because of the small core diameter, alignment of single mode cores with a connector is more critical than in the case of a multi-mode fiber. Alignment of the fibers becomes even more of an issue in the case of multiple channel single mode cables where multiple fiber optic connections must be aligned with a high degree of precision. 
   SUMMARY 
   A hermaphroditic connector for mounting to a cable having a plurality of optical fibers and connecting the fibers to mating optical fibers having termini mounted on the ends thereof including a plug insert for mounting the termini and a generally cylindrical plug body for receiving the plug insert therein. The plug body includes a mating end having a plurality of mating features configured to engage the corresponding mating features of a second connector to align the termini of the connector with the termini of a second connector in opposed relationship. A plurality of ears extend radially outward from the forward end of the mating end of the plug body. 
   The connector includes a coupling nut slidably and rotatably mounted on the plug body and having a generally cylindrical wall and a groove for receiving an ear of the connector and the ear of a mating connector in opposed relationship therein. The groove extends around an inside surface of the cylindrical wall adjacent a first end of the coupling nut so that the groove is aligned with an ear of the connector and an ear of a second connector when the coupling nut is moved to its forward position. Rotation of the coupling nut captures the ear of the connector and the ear of a second connector in opposed relationship in the groove. 
   The connector may include a spring disposed in annular space between the plug body and the coupling nut for biasing the coupling nut in a rearward position on the plug body. In one variation, a pair of ears are positioned at opposed positions on the circumference of the mating end of the plug body and the ears pass through a pair of opposed openings into the groove when the coupling nut is moved into the forward position. In another aspect, the connector includes a shield for mounting the plug insert in the plug body wherein the shield includes alignment features for aligning the shield and plug insert in a selected rotational orientation relative to the plug body. The alignment features may include a plurality of pins extending longitudinally forward from the shield for engaging bores formed in the plug body. 
   In another embodiment, a hermaphroditic connector includes a plug insert for mounting the termini and a plug body for receiving the plug insert therein. The plug body has a central longitudinal axis and a mating end with first and second openings extending longitudinally therethrough for receiving the ends of termini therein. The openings are positioned on either side of a plane extending longitudinally thorough the plug body perpendicular to a line connecting the centers of the openings and intersecting the longitudinal axis of the plug body which divides the mating end into first and second halves. A generally cylindrical tower having a longitudinal passage therethrough aligned with the first opening for receiving an end of a termini of a corresponding mating connector extends from the first half of the mating end of the plug body. First and second mating pins having first opposed concave faces defining a tower receiving aperture therebetween for receiving the tower of a corresponding mating connector extend longitudinally from the second half of the mating end of the plug body. The mating pins include substantially flat second faces aligned with the plane dividing the mating end into first and second halves and substantially convex third faces disposed between the first and second faces. The first half of the mating end of the plug body includes first and second recesses formed therein on opposing sides of the tower for receiving the mating pins of a corresponding mating connector. The recesses include first, substantially concave walls formed on opposing sides of the tower, second substantially flat walls aligned with the plane dividing the mating end into first and second halves and substantially convex third walls disposed between the first and second walls. 
   In one aspect, the connector further includes a pair of circumferentially opposed ears extending radially from the mating end of the plug body between a pair of chords equidistant from the axis of the plug body and perpendicular to the plane dividing the mating end into first and second halves. In one embodiment, the ears have a semi-circular cross section and a combined radial length of approximately 15% to 20% of the diameter of the mating end of the plug body. In another aspect, the connector includes a pair of alignment pins extending from the forward end of the mating end of the plug body. The mating pins of the connector have longitudinally extending bores formed therein for receiving the alignment pins of a corresponding connector. 
   In yet another embodiment, the connector includes a plug insert for mounting the termini, a plug body for receiving the plug insert therein and a radially extending stop wall formed on an outside surface of the cylindrical wall. The connector further includes a generally cylindrical coupling nut having a stop formed on an inside surface thereof. The stop of the connector engages the stop wall of the plug body (same connector) upon rotation of the coupling nut to couple the connector with the mating connector such that rotation of the coupling nut is limited to a predetermined arc. The predetermined arc may be between about 80 degrees and about 110 degrees. 
   In another aspect, the connector further comprising a compressible retaining member positioned in a recess formed in an outside surface of the stop wall. A corresponding projection extends radially inward from an inside wall of the coupling nut for engaging the compressible retaining member of a corresponding second connector Upon rotation of the coupling nut, the projection of a corresponding second connector compresses and passes the retaining member to engage the connector with a corresponding mating connector, the compressible member retaining the coupling nut in engagement with the mating connector by preventing inadvertent reverse rotation of the coupling nut. The compressible member may be a spring, a solid resilient body, a compressible cylinder or a spring-biased body having an arcuate surface for engaging the projection. In one variation, the projection is wedge-shaped with an inclined wall to facilitate engagement with a compressible member of a corresponding mating connector. 
   In still another embodiment, a hermaphroditic connector for mounting to a cable having a plurality of optical fibers and connecting the fibers to mating optical fibers includes a plug body and a plug insert having a generally cylindrical body including a circular forward face formed integral with the body including a plurality of apertures extending through the face and configured for slidably mounting termini in the plug insert. The plug insert further comprises an axial slot extending rearwardly from the face and at least one axial slot extending rearward from the forward face. The slot is sufficiently long and wide to form an “s-ing” chamber in which optical fibers connected to the termini may flex upon coupling of the connector with a corresponding second connector with the faces of the connectors in abutting relation. A rear section of the plug insert extending rearward of the slot includes a rearwardly opening socket, a forwardly tapered hole having a substantially conical wall that opens into the slot and a central passage extending axially between the socket and the forwardly tapered hole. A wedge having a nose with profile substantially matching a portion of the wall of the forwardly tapered hole is operable to engage the plug insert and compress and hold the strength member of a fiber optic cable between the wedge and the conical wall. The socket may include internal threads to engage a threaded end portion of the insert for coupling the wedge into the socket. 
   In another aspect the connector comprises an end cap enclosing the plug insert, the end cap including internal threads for threadedly engaging corresponding threads on a rear end of the plug body, the end cap including at least one longitudinally extending slot that enables the end cap to be compressed onto the plug body with a set screw. In yet another aspect, the plug insert includes recesses formed around each of the apertures for retaining termini in the apertures. 
   In one aspect, a terminus for use with a fiber optic connector includes a ferrule having first and second ends and an axial bore adapted to receive an optical fiber with an elongate pin body including a longitudinally extending central opening configured to receive the ferrule with the ferrule extending axially from a first end of the pin body. The elongate pin body includes a fixed collar extending around the circumference of the pin body, a shaft portion extending from the fixed collar and a circumferential groove extending around the shaft portion remote from the first end of the pin body. A floating seal is slidably mounted on the shaft portion. The floating seal includes a cylindrical sidewall with first and second ends and an axial passage therethrough for receiving the shaft portion of the pin body. The floating seal further includes an annular groove extending around the outside circumference of the cylindrical sidewall, a first annular recess extending around the inner circumference of the axial passage at the first end of the cylindrical sidewall and a second annular recess extending around the inner circumference of the axial passage at the second end of the cylindrical sidewall. The first and second annular recesses define an annular ridge extending around the inner circumference of the cylindrical sidewall therebetween. In one variation, the cylindrical sidewall includes an angled shoulder at the interior end of the first annular recess. First and second resilient sealing members such as O-rings are disposed in the annular groove and the second annular recess, respectively. 
   The terminus further includes a slip collar disposed on the shaft portion of the pin body, a retainer positioned in the circumferential groove and a spring disposed around the shaft portion between the second collar and the slip collar. A first end of the spring abuts the fixed collar whereby the spring biases the floating seal and slip collar away from the first end of the pin body. In this configuration, the pin body is pivotable relative to the floating seal around the annular ridge. In one aspect, the floating seal has a first internal diameter across the first annular recess, a second internal diameter across the second annular recess and a third internal diameter at the annular ridge wherein the second internal diameter is larger than the first internal diameter and the first internal diameter is larger than the third internal diameter. 
   In another aspect, the terminus includes a first fixed collar formed around the first end of the pin body, a second fixed collar spaced from the first collar wherein a first end of the spring abuts the second fixed collar whereby the spring biases the floating seal and slip collar away from the first end of the pin body. 
   In another variation, a terminus for use with a fiber optic connector includes an elongate pin body having first and second ends with a longitudinal opening therethrough. A ferrule, including an axial bore adapted to receive an optical fiber, is secured in the longitudinal opening at a first end of the pin body such that the ferrule extends in an axial direction from the pin body. The elongate pin body includes a first fixed collar extending around the circumference of the pin body, a second fixed collar spaced from the first fixed collar and a shaft portion extending from the second fixed collar. A floating seal having first and second ends is slidably mounted on the shaft portion, the floating seal including a cylindrical sidewall that defines an axial passage therethrough for receiving the shaft portion of the pin body. In one aspect, the floating seal has a first annular recess extending around the inner circumference of the axial passage at the first end of the cylindrical sidewall and a second annular recess extending around the inner circumference of the axial passage at the second end of the cylindrical sidewall. The first and second recesses define an annular ridge extending around the inner circumference of the cylindrical sidewall between the first and second annular recesses. In one aspect, the annular ridge defines a pivot whereby the pin body is pivotable relative to the floating seal around the pivot 
   A slip collar is disposed on the shaft portion of the pin body and a spring disposed around the shaft portion between the second collar and the slip collar wherein the slip collar has a first end that abuts the second collar such that the spring biases the floating seal and slip collar away from the first end of the pin body. A resilient sealing member disposed in the second annular recess seals in an axial direction between the cylindrical sidewall and the shaft portion and in a radial direction between the cylindrical sidewall and the slip collar. A retainer positioned on the shaft portion of the pin body secures the spring and slip collar on the pin body. In one variation, the terminus includes an annular groove extending around the outside circumference of the cylindrical sidewall adjacent the first end of the seal and a resilient sealing member disposed in the annular groove. 
   In another aspect, a terminus for use with a fiber optic connector includes a ferrule mounted in a central opening of a pin body such that the ferrule extends axially from a first end of the pin body. The elongate pin body includes a large diameter first portion adjacent the first end and shaft portion extending from the large diameter first portion. A floating seal having a cylindrical sidewall defining an axial passage is slidably mounted on the shaft portion. The floating seal has first and second ends with an annular groove formed around the outside circumference of the cylindrical sidewall adjacent the first end. First and second annular recesses extending around the inner circumference of the axial passage at the first and second ends of the sidewall define an annular ridge extending around the inner circumference of the cylindrical sidewall between the first and second annular recesses. First and second resilient sealing members are disposed in the annular groove and the second annular recess, respectively. In one variation a retainer is disposed on the shaft portion between the floating seal and the second end of the elongate pin body. A spring positioned between the large diameter first portion of the pin body and the retainer biases the floating seal away from the first end of the pin body. In this configuration, the pin body is pivotable relative to the floating seal. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding, reference is made to the drawings, wherein like reference numbers are used herein to designate like elements throughout, and wherein: 
       FIG. 1  is a front perspective view of a connector in accordance with one embodiment; 
       FIG. 2  is front end view of the connector of  FIG. 1 ; 
       FIG. 3  is an exploded view of the connector of  FIG. 1 ; 
       FIG. 4  is a first partial sectional and partial cutaway view of the connector of  FIG. 1  taken along line  4 - 4  of  FIG. 2 ; 
       FIG. 5  is a second partial sectional and partial cut away view of the connector of  FIG. 1 , rotated ninety degrees from the view of  FIG. 4 , taken along line  5 - 5  of  FIG. 2 ; 
       FIG. 6  is a third partial sectional and partial cut away view of the connector of  FIG. 1 , rotated ninety degrees from the view of  FIG. 5  and one hundred eighty degrees from the view of  FIG. 4 , taken along line  6 - 6  of  FIG. 2 ; 
       FIG. 7  is a partial sectional and partial cut away view of the connector of  FIG. 1  coupled to a second, identical connector with portions of the second connector omitted; 
       FIG. 8  is a side view of the connector of  FIG. 1  coupled to a mating receptacle; 
       FIG. 9  is a partial sectional and partial cutaway view of the connector and receptacle of  FIG. 8 ; 
       FIG. 10  is a front end view of a terminus illustrated in  FIG. 1 ; 
       FIG. 11  is a sectional view of the terminus of  FIG. 10  taken along line  11 - 11  of  FIG. 10 ; 
       FIG. 12  is a front end view of an alternate terminus suitable for use in connection with the connector of  FIG. 1 ; 
       FIG. 13  is a sectional view of the terminus of  FIG. 12  taken along line  13 - 13  of  FIG. 12 ; 
       FIG. 14  is a first perspective view of the coupling nut illustrated in  FIG. 1 ; 
       FIG. 15  is a side view of the coupling nut of  FIG. 14 ; 
       FIG. 16  is a rear end view of the coupling nut of  FIG. 14 ; 
       FIG. 17  is a sectional view of the coupling nut of  FIG. 14 , taken along line  17 - 17  of  FIG. 16 ; 
       FIG. 18  is a second perspective view of the coupling nut of  FIG. 14 ; 
       FIG. 19  is an enlarged perspective view of the plug body illustrated in  FIG. 1 ; 
       FIG. 19A  is an enlarged partial front end view of the plug body of  FIG. 19 ; 
       FIG. 19B  is a partial side and partial cutaway view of the forward end of the plug body of  FIG. 19 ; 
       FIGS. 20-22  are partial sectional views of the encircled area of  FIG. 19  wherein alternate versions of a compressible member are illustrated therein; 
       FIG. 23  is an exploded view of the receptacle of  FIGS. 8 and 9 ; 
       FIG. 24  is a front end view of the receptacle of  FIG. 23 ; 
       FIG. 25  is partial sectional and partial cutaway view of the receptacle of  FIG. 23  taken along line  25 - 25  of  FIG. 24 ; 
       FIG. 26  is partial sectional and partial cutaway view of the receptacle of  FIG. 23  taken along line  26 - 26  of  FIG. 24 ; 
       FIG. 27  is a rear end view of an alternate coupling nut; 
       FIG. 28  is a side view of the coupling nut of  FIG. 27 ; 
       FIG. 29  is a front end view of the coupling nut of  FIG. 27 ; 
       FIG. 30  is a sectional view of the coupling nut of  FIG. 27  taken along line  30 - 30  of  FIG. 29 ; 
       FIG. 31  is a perspective view of the coupling nut of  FIG. 27 ; 
       FIG. 32  is a partial sectional drawing of an alternate terminus in accordance with one embodiment; 
       FIG. 33  is a sectional view of a seal for use with the terminus of  FIG. 32 ; and 
       FIG. 34  is an enlarged view of the encircled portion of  FIG. 32 . 
   

   DETAILED DESCRIPTION 
   Referring to  FIGS. 1-7 , in one embodiment, a hermaphroditic connector  10  for connecting a two channel single mode fiber optic cable includes a coupling nut  14  slidably mounted over a plug body  16 . An end cap  18  is positioned over rear end of plug body  16  with a resilient boot  12  mounted on the rearmost end of end cap  18 . 
   As best illustrated in  FIGS. 3-7 , connector  10  includes a plug insert  20  mounted in plug body  16  for mounting a plurality of termini  45  inside the connector. Termini  45  are configured for mounting on the terminal ends of optical fibers to enable mating of the fibers. Plug insert  20  includes generally cylindrical front section  22  and a larger diameter rear section  24 . A longitudinal slot  26  or “s-ing” chamber formed in forward section  22  of plug insert  20  between a forward circular face  28  of the front section and rear section  24  provides a space in which fiber optic cables may flex when connector  10  is mated to another connector  10  or to receptacle. Termini  45  are slidably mounted in a pair of circumferentially opposed semicircular apertures or cutouts  32  formed in the forward most face  28  of plug insert  20 . Face  28  with cutouts  32  forms a guide or “snowflake” integral with plug insert  20  for retaining termini  45  in position in the insert. 
   Turning to  FIGS. 3 ,  10  and  11 , terminus  45  includes a pin body  47  with an enlarged generally cylindrical forward portion  49  having a ceramic ferrule  46  fitted into a longitudinal recess or socket  48  formed in the forward portion  49 . Socket  48  may have a slight inward taper to facilitate press fitting ferrule  46  into the socket. Terminus  45  is mounted on plug insert  20  with a smaller diameter rear end portion  50  of pin body  47  passing through cutout  32 . 
   A coil spring  54  fitted over end portion  50  of pin body  47  biases a slip collar  56  against the front of face  28  of plug insert  20 . Slip collar  56  is sized to fit into a recess or counterbore  34  formed around cutout  32  to aid in positioning the collar. A retainer such as E-clip  58  is fitted over rear end portion  50  of pin body  47 , engaging one of a plurality of grooves formed in the end portion. E-clip  58  is positioned against the rear of face  28  such that the slip collar  56  and retainer  58  are on opposing sides of face  28 . 
   Spring  54  is compressed between enlarged end portion  49  and a floating annular ring  53 , biasing the slip collar against the front of face  28 . When connector  10  is coupled to a mating connector, as illustrated in  FIG. 7 , ferrule  46  is pressed against the ferrule end of a mating terminus, forcing pin body  47  to move rearward, compressing spring  54 . Spring  54  maintains a biasing force against pin body  47 , holding ferrule  46  against the ferrule end of the mating terminus while permitting rearward longitudinal movement of ferrule  46  and pin body  47  over a predetermined distance. 
   A circumferential groove  51  formed in the outer surface of forward portion  49  receives annular ring  53 , which in turn includes a groove  55  for receiving an O-ring  57 . Ring  53  is formed with an inside diameter that is larger than the outside diameter of forward portion  49  across circumferential groove  51  such that an annular space  59  is formed between ring  53  and forward portion  49 . The arrangement of ring  53  in groove  51  enables the ring, along with O-ring  57 , to float relative to pin body  47  when terminus  45  is positioned in bore  106  of shield  100 , permitting O-ring  57  to conform more closely to the inside surface of the bore. A second O-ring  61  is mounted in an annular space  63  formed by the forward end of ring  53  and a circumferential recess  65  formed in forward portion  49  of pin body  47 . O-ring  61  seals the interface between pin body  47  and ring  53 . 
   While pin body  47 , slip collar  56  and spring  54  are preferably formed from a suitable metal, it is contemplated that the pin body may be formed from other materials such as suitable plastics and/or ceramics. Similarly ferrule  46  may also be formed from materials other than ceramics such as a suitable plastic or metal. 
   A bore  70  for receiving optical fiber  76  extends from the rearmost end  72  of pin body  47  to an outwardly tapering section  74  that opens into socket  48 . A corresponding bore  80 , aligned with bore  70 , extends through ferrule  46 . A tapered guide section  82  formed at the rearmost end of ferrule  46  aids in guiding optical fiber  76  into bore  80 . Bore  80  has a diameter slightly larger than the cladding of the fiber optic which is secured in the bore with an epoxy or similar adhesive. After the optical fiber is secured in ferrule  46 , the fiber is cleaved flush with the forward end  84  of the ferrule and polished to facilitate operative connection of the ferrule with a mating ferrule. 
     FIGS. 12 and 13  illustrate an alternate terminus  40  wherein groove  51 , annular ring  53  and O-rings  57  and  61  are omitted. Terminus  40  includes a pin body  42  with a generally cylindrical forward portion  44  having a ceramic ferrule  46  fitted into socket  48 . Terminus  40  may be suitable for use in applications where the compliant sealing mechanism of terminus  45  is deemed unnecessary. The remaining components of terminus  40  are substantially identical to the correspondingly numbered components of terminus  45  and function is substantially the same manner. 
   Turning to  FIGS. 3-7 , a generally cylindrical shield  100  fits over front section  22  of the plug insert  20 , covering termini  45 . Shield  100  is typically metal, but may be formed from other materials. Shield  100  includes an expanded diameter rearwardly opening portion  102 , a center portion  103  and a solid forward portion  104  having longitudinal bores  106  for receiving termini  45  extending therethrough. Alignment of shield  100  and plug insert  20  with plug body  16  is accomplished with a pair of offset alignment pins  116  that extend longitudinally from the forward end of the shield. 
   Alignment pins  116  are configured to fit into and through holes  117  formed in the face  170  of plug body  16  and into bores  118  in each of a pair of mating pins  200  of a corresponding mating connector. Pins  116  are positioned on the same side of and offset from a diameter of the shield so that shield  100  can be positioned in only one rotational orientation relative to plug body  16  to align the pins with holes  117 . This configuration of pins  116  insures that each of ferrules  46  are each aligned with the corresponding mating ferrule when connector  10  is coupled to a second connector or shield. The length of alignment pins  116  is such that the pins must enter holes  117  before ferrules  46  approach the rear side of face  170  as the shield  100  is slid over plug insert  20 . This arrangement prevents ferrules  46  from contacting the rear face of forward portion  104  of shield  100  rather than entering bores  106 , thereby reducing the possibility of damage to the ferrules and the optical fibers mounted therein. 
   Referring to  FIGS. 3 ,  5  and  11 , as shield  100  is slid over insert  20 , bores  106  receive the forward end portions  49  of pin bodies  47  such that ferrules  46  extend forward from the shield with the forward ends of the pin bodies flush with the forward end of the shield. The diameter of bores  106  is only slightly larger than that of the forward portions  49  of pin bodies  47  so as to maintain proper alignment of ferrules  46 . O-ring  57  mounted in a groove  55  formed in the outside surface of forward portion  40  of pin body  47  seals between the inside wall of bore  106  and the pin body. An annular groove  113  formed on the inside surface of enlarged end portion  102  of shield  100  is aligned with corresponding groove  36  in the front section  22  of plug insert  20  to receive O-ring  37  to aid in retaining shield  100  on plug insert  20 . O-ring  37  also serves as an environmental seal preventing foreign material from entering the plug insert/shield assembly. 
   As best illustrated in  FIGS. 3 ,  4  and  5 , plug insert  20  includes a central opening  120  extending longitudinally between the rearmost end of the insert and “s-ing” chamber  26 . Opening  120  includes a rearwardly opening socket  122  having internal threads  126  and a forwardly tapering conical hole  124  that extends from socket  122  to chamber  26 . A wedge  130  including a conical nose  134  having a profile to match conical hole  124  and a cylindrical middle section  136  with exterior threads  140  for engaging threads  126  of socket  122  secures a fiber optic cable in insert  20 . The cable is extended through a central bore  138  passing longitudinally through wedge  130  and the strength member of the cable, typically a woven sheath of high strength synthetic material such as Aramid® or Kelvar® strands is wrapped over the nose of the wedge. 
   Wedge  130  is inserted into opening  120  and rotated to engage threads  140  with threads  126  of socket  122 . As wedge  130  is tightened, the cable strength member is pinched between nose  134  and the wall of conical hole  124 , securing the cable in the insert. A hexagonal nut  142  formed at the rear end of wedge  130  allows tightening of the wedge with a wrench. Similarly, flats  144  formed on the exterior of plug insert  20  allow the insert to be grasped with a wrench as the wedge is tightened. An O-ring  227  seated in a groove  229  formed around the outside of perimeter of wedge  130  rearward of threads  140  seals between wedge  130  and insert  20 . 
   Shield  100  with plug insert  20  is fitted into plug body  16 . Plug body  16  includes a cylindrical wall  154  that defines a rearwardly opening cavity  156  for receiving plug insert  20  and shield  100 . An annular ring  152  formed midway along the length of plug body  16  includes a groove  158  for receiving an O-ring  157  that seals between plug body  16  and coupling nut  14 . An enlarged rear end portion  160  of plug body  16  includes exterior threads  162  for engaging corresponding interior threads  404  of a cylindrical end cap  18 . 
   End cap  18  encloses plug insert  20  and wedge  130  in plug body  16 . End cap  18  includes an enlarged forward cylindrical wall  402  having internal threads  404  formed therein and a second, rear cylindrical wall  406  having a radially extending lip  408  formed around the outer perimeter of wall. A first, longitudinal slot  412  extends rearwardly from the forward end of wall  402 , intersecting a second slot  414  that extends approximately 180 degrees around the circumference of wall  402 . Slots  412  and  414  allow wall  402  to be compressed and locked onto the rear end portion  160  of plug body  16  with a cap screw  416  after end cap  18  has been threaded onto the plug body. 
   A hollow conical resilient boot  12  is fitted onto end cap  18  to inhibit lateral flexing of a fiber optic cable passing through end cap  18  into connector  10 . Boot  12  includes a forward cylindrical collar  422  with an annular groove  424  formed on the inside surface of the collar. Boot  12  is manufactured from a stretchable synthetic rubber or similar material such that the collar  422  can be stretched to fit over wall  406  with lip  408  engaging groove  424  to secure the boot on end cap  18 . Boot  12  may be provided with a series of slots or cuts  426  extending partially around the circumference of the boot at spaced apart intervals. The width and spacing of slots  426  may be varied to control the resistance of the boot  12  to lateral flexing. 
   A fiber optic cable passing through boot  12  and end cap  18  extends through a resilient seal grommet  244  positioned in a rearwardly opening recess  246  formed in the rearmost end of wedge  130 . Grommet  244  provides a seal around a fiber optic cable passing through end cap  18  into wedge  130 . A conical washer  248 , formed from a low friction material, protects seal grommet  244  from deformation as end cap  18  is tightened onto plug body  16 . 
   Plug body  16  includes a pair of circumferentially opposed, longitudinal slots  168  formed in end portion  160  of the body. Slots  168  receive a corresponding pair of cylindrical projections or keys  30  that extend radially from the rear end portion  24  of plug insert  20 . Engagement of keys  30  in slots  168  insures proper alignment of plug insert  20  and termini  45  relative to plug body  16 . 
   Referring to  FIGS. 2 ,  4 - 9  and  19  and  19 A-B the forward or mating end  166  of plug body  16  includes a recessed circular face  170  having openings  172 ,  174  through which ferrules  46  extend. In one embodiment, the diameter of mating end  166  is approximately 0.56 inches and the distance between the centers of openings  172 ,  174  is approximately 0.2 inches. Openings  172 ,  174  are formed in opposing half sections  178 ,  180  of face  170 . Opposing half sections  178 ,  180  of face  170  are defined by a plane  175  ( FIG. 2 ) that extends through plug body  16  along a central longitudinal axis of the body perpendicular to a line connecting the centers of openings  172 ,  174 . 
   A hollow cylindrical tower  210  extending longitudinally from first half section  178  of face  170  of plug body  16  includes a central passage  212  extending longitudinally through the tower. In one embodiment, tower  210  has a diameter of approximately 0.19 inches and extends approximately 0.21 inches beyond the forward most end  166  of plug body  16 . Tower  210  is formed over opening  172  with passage  212  aligned with the opening to receive a ferrule of a second connector in mating relationship with ferrule  46  of connector  10 . A split sleeve  216  is positioned inside a cylindrical shroud  214  coaxial with opening  172  and passage  212  to align ferrule  46  in a mating orientation. Shroud  214  and sleeve  216  are retained between a lip  220  formed around the inside circumference of the forward end of passage  212  and an annular retainer  222  fitted into the rear end of passage  212 . In one variation, sleeve  216  is formed from a ceramic material while shroud  214  is constructed from an appropriate metal. It is, however, contemplated that sleeve  216  and shroud  214  may be formed from any suitable metal, ceramic, plastic or other material. 
   Referring to  FIGS. 2 ,  19  and  19 A, plug body  16  includes a pair of mating features such as pins  200  extending longitudinally from second half section  180  of face  170  on either side of opening  174 . Mating pins  200  have a cross section approximating a quarter circle with rounded corners, opposing concave sides  230 , substantially flat sides  231  aligned with plane  175  and outward convex sides  233 . Mating pins  200  are oriented with concave sides  230  facing opening  174  such that the mating pins and tower  210  define an aperture  232  therebetween for receiving the tower of a corresponding mating connector or receptacle. In one embodiment, mating pins  200  extend approximately 0.21 inches beyond the forward most end  166  of plug body  16 . 
   Plug body  16  includes axially extending grooves  236  formed in the inside surface of wall  154  that extend forward from face  170  adjacent tower  210 . Grooves  236  along with tower  210  define apertures  238  for receiving the corresponding mating pins of an identical connector or receptacle. In one embodiment, grooves  236  extend approximately 0.21 inches rearward from forward end  166  of plug body  16 . Apertures  238  have opposing concave walls  235 , substantially flat walls  237  aligned with plane  175  and convex outward walls  239 . When connector  10  is coupled with a second connector, the tower and mating pins of the second connector are aligned with and inserted into apertures  232 ,  238  as the connectors are brought together. Similarly, tower  210  and mating pins  200  of connector are inserted into the corresponding apertures of the second connector. 
   A pair of mating ears  250  extend radially outward from mating end  166  of plug body  16  for coupling connector  10  to a second connector. In one embodiment, each of mating ears  250  have a radial length of approximately 0.05 inches and a circumferential width of approximately 0.20 inches. As best shown in  FIG. 19A , ears  250  are located 180 degrees apart on the circumference of plug body  16  between parallel chords e and e′ equidistant from the center of the longitudinal axis of plug body  16 . As illustrated, ears  250  have a generally semi-cylindrical geometry with a semicircular cross section having a flat mating face  252  flush with mating end  166  of the body. Faces  252  and forward most end  166  of plug body  16  define a mating plane p-p′ ( FIGS. 9 ,  19 B). Faces  252  are configured to oppose the corresponding faces of the mating ears  252 ′ of a second connector  10 ′ ( FIG. 7 ) when connector  10  is coupled to the second connector. 
   Referring to  FIGS. 4-9  and  14 - 18 , coupling nut  14  is slidably and rotatably mounted over plug body  16  for coupling connector  10  to a receptacle or a second connector. Coupling nut  14  includes a cylindrical wall  272  defining a central longitudinally extending passage  280  for receiving plug body  16 . A coil spring  288  disposed in an annular space  290  between wall  272  and wall  154  of plug body  16  abuts annular ring  152  of plug body  16  to bias coupling nut  14  in the rearward direction. A retainer ring  292  positioned in an annular groove  294  formed in the inside surface of wall  272  near the rear end  286  of the wall retains spring  288  and coupling nut  14  on plug body  16 . O-ring  157  positioned in groove  158  of plug body  16  prevents foreign material from entering space  290 . 
   As best illustrated in  FIGS. 14-18 , coupling nut  14  includes a pair of first ribs  300  that extend radially inward from the inside circumference of wall  272  adjacent coupling end  284  of the coupling nut. Ribs  300  each extend over equal and opposed arcs along wall  272 . Openings  304  between the ends  302  of first ribs  300  are positioned 180 degrees apart on the inside circumference of wall  272 . 
   A pair of second ribs  310  extends around the inside of wall  272  rearward of ribs  300  to form a pair of arcuate grooves  330  between first ribs  300  and second ribs  310 . Second ribs  310  are formed substantially parallel to ribs  300  and extend over the same arcuate intervals or segments as ribs  300  around the inside circumference of wall  272 . Arcuate grooves  330  have forward walls  322  defined by ribs  300  and rear walls  324  defined by ribs  310 . Walls  322  and  324  are each substantially perpendicular to a longitudinal axis  325  extending through the center of coupling nut  14 . The ends  312  of second ribs  310  define opposed openings  314  positioned 180 degrees apart on the inside circumference of wall  272 . Openings  314  are longitudinally aligned with openings  304  in first ribs  300 . 
   Ribs  300 ,  310  form a substantially circular longitudinal opening  332  having a diameter slightly larger than the diameter of forward end  166  of plug body  16 . Openings  304  and  314  are sized such that the width of the openings is slightly larger than the width of ears  250  so that coupling nut  14  can slide over plug body  16  when ears  250  are aligned with openings  304  and  314 . 
   Referring to  FIGS. 7 ,  14 - 18  and  19 A, connector  10  is coupled to a second connector by aligning and inserting the mating pins  200  and towers  210  of each of the connectors into the corresponding apertures  232 ,  238  of the second connector. Alignment of the mating pins  200  and tower  210  with the corresponding apertures also aligns ears  250  of connector  10  with the corresponding ears of the second connector so that faces  252  of the ears oppose the corresponding faces  252 ′ of the second connector as illustrated in  FIG. 7 . When an ear  250  is placed in opposed mating relationship with an ear  250 ′ of a second connector  10 ′ or receptacle, the opposed ears form a generally cylindrical projection having a substantially circular cross-section. 
   As connectors  10  and  10 ′ are pushed together, ferrules  46 ,  46 ′ of the aligned connectors meet, compressing springs  54 ,  54 ′ of termini  45  as the termini move to the rear. Coupling nut  14  is pushed from the rearward position forward over plug body  16  until opposed ears  250 ,  250 ′ of each connector pass through openings  304  between the ends of first ribs  300  and into alignment with grooves  330 . Coupling nut  14  is then rotated approximately 90 degrees, trapping ears  250 ,  250 ′ of connectors  10  and  10 ′ in grooves  330  between ribs  300 ,  310 . 
   Ribs  300 ,  310  are configured such that the width of groove is less than the width or diameter of a pair of opposed ears  250  plus the predetermined longitudinal travel of opposed ferrules  46  permitted by springs  54 . In this manner, ferrules  46  of mated connectors  10  are maintained in biased opposed contact when the connectors are coupled. In the illustrated embodiment, the distance, denoted Wg ( FIG. 17 ), between walls  322  and  324 , i.e., the width of grooves  330 , is selected to substantially match the combined width, denoted We ( FIGS. 7 ,  9 ) of the opposed ears  250  when connector  10  and the second connector are pushed firmly together. Thus, the groove  330  holds ears  250 , and therefore connectors  10  (or a connector and receptacle) operatively together against the biasing force of the termini springs  54 . 
   Turning to  FIGS. 14-19  rotation of coupling nut  14  is limited by means of one or more stops  316  formed on the inside of wall  272  of the coupling nut rearward of second ribs  310 . Stops  316  engage corresponding stop walls  224  that extend radially outward from wall  154  of plug body  16 . Stops  316  and stop walls  224  are circumferentially positioned on coupling nut  14  to limit the rotation of coupling nut  14  to approximately 100 degrees. These features prevent over-rotation of coupling nut  14  when connector  10  is coupled to a second connector. 
   Coupling nut  14  is maintained in the coupled position by means of a compressible member  226  positioned in a recess  228  in each of stop walls  224 . As coupling nut  14  is rotated to the coupled position, a pair of opposing projections or wedges  318  formed on the inside surface of wall  272  of the coupling nut compress and rotate past members  226 . When wedges  318  pass members  226 , the members expand to the uncompressed state, preventing coupling nut  14  from rotating in the reverse direction due to vibration or incidental movement of connector  10 . Wedges  318  are positioned on the inside circumference of coupling nut  14  so that wedges  318  rotate over members  226  as the nut is rotated approximately 90 degrees from its initial position. In one variation, wedges  318  include an inclined face  320  to facilitate movement of member  226  over the wedge. Since stops  316  prevent further rotation of coupling nut  14 , the nut is retained in the selected rotational position. 
   Members  226  and wedges  318  may be selected and sized as to permit rotation of coupling nut  14  in the reverse direction only with the application of a predetermined force. As illustrated in  FIGS. 20-22 , member  226  may comprise a coil spring  226   a , ( FIG. 20 ) a compressible plastic or rubber cylinder  226   b  ( FIG. 21 ), or a spring biased spherical member  226   c  ( FIG. 22 ). In one embodiment, illustrated in  FIG. 21A , member  226   d  comprises a phosphorous bronze metal cylinder, similar to a roll pin. Preferably, members  226  are selected to have sufficient resistance to compression to provide a user with a discernable tactile indication or “snap” when wedges  318  rotate over the members, indicating that connector  10  is fully engaged. 
   Conventional bayonet connectors rely on the engagement of one or more pins in the short leg of a J-shaped groove to prevent the connector from inadvertently loosening. Stop walls  224  and stops  316  along with compressible members  226  and wedges  318  provide a rotational stop and click mechanism that eliminates the need for J-shaped grooves of conventional bayonet-type connectors, permitting the use of a straight groove for capturing and holding receiving ears  252 . The use of a straight groove or grooves  330  eliminates the rearward movement of the connector faces associated with the pins of conventional bayonet connector moving into the short leg or recess of the J-shaped groove. 
   Stop walls  224  in conjunction with second ribs  310  also provide an additional alignment feature. When coupling nut  14  is in the rearward position, walls  224  are positioned in openings  314  between second ribs  310 , preventing rotation of the coupling nut. In order to rotate coupling nut  14 , the nut must be moved forward until second ribs  310  are forward of stop walls  224 . This feature insures that coupling nut  14  is maintained in the proper orientation for coupling when not in use. 
   In the embodiment shown in  FIGS. 14-18 , a pair of circumferentially extending slots  336  are formed during the machining process extending completely though the outer surface of coupling nut  14 . In an alternate embodiment, a coupling nut  15 , illustrated in  FIGS. 27-31  is formed without an externally visible slot  336 , but with substantially identical internal features, identified with the same reference numbers, as coupling nut  14 . Coupling nut  15  can be used as part of a connector  10  substantially identical to that illustrated in  FIGS. 1-8 , except without the externally visible slot  336 . Operation of the connector  10  with alternate coupling nut  15  is substantially identical to that previously described. 
   Referring to  FIGS. 8 ,  9  and  23 - 26 , a receptacle  500 , adapted for panel mounting, includes a forward mating fixture  502  having a base  504  and substantially identical mounting features as the forward end  166  of plug body  16 . Such features are identified with the same reference numbers previously used in connection with plug body  16 . Fixture  502  is mounted on the enlarged diameter forward end  506  of a cylindrical housing  508  that defines a cylindrical cavity  512  for receiving a pair of termini  514  having ferrules  516 . Base  504  includes a flattened side  518  that abuts a ledge  520  formed on the forward end  506  of housing  508  to align the base in the proper rotational orientation relative to the housing. A pair of alignment pins  509  extend longitudinally from the forward end  506  of housing  508  for engagement in bores  118  of a corresponding connector. Fixture  502  is mounted on housing  508  with a pair of screws  524  that engage threaded apertures  526  formed in the housing. An O-ring  510  is seated in an annular groove  511  formed on the forward end  506  of housing  508  to seal between fixture  502  and housing  508 . 
   Termini  514  are mounted in cylindrical housing  508  of receptacle  500  with a guide  528  that receives the ends  530  of pin bodies  532  of the termini in cutouts  535 . Guide  528  is retained in housing  508  with a threaded insert  525  that engages internal threads  527  formed on the inside surface of the housing. Ferrules  516  are biased with springs  534  in the same manner as ferrules  46  described above to provide a predetermined amount of longitudinal travel during connection. Ferrules  516  extend through a recess  536  formed in the rear face of base  504  into fixture  502  for mating engagement with the ferrules of a corresponding connector such as connector  10 . As best illustrated in  FIG. 9 , when connector  10  is coupled with receptacle  500 , the mating ends of ferrules  46  of the connector and receptacle are substantially coplanar with the mating faces  252  of ears  250  of the connector and receptacle. 
   A rearwardly facing, radially extending wall  540  extends between a threaded rear end portion  542  of receptacle  500  and enlarged diameter portion  506 . Threaded end portion  542  of receptacle  500  is configured for insertion though a panel opening with a wall  540  abutting the panel. An O-ring  544  seated in an annular groove  546  formed in wall  540  provides an environmental seal between connector  500  and the wall of the panel. Receptacle  500  is secured in the panel wall with a nut  550  threaded over end  542  of the receptacle. 
   Referring again to  FIG. 5 , termini  45  should be sealed from the external environment to insure proper functioning of the connector. Effective sealing generally requires relatively close tolerances between an exterior surface of a terminus and the bore in which it is mounted. However, in order to align termini  45  of connector  10  with the corresponding termini of a mating connector, each of the termini should be able to move a limited distance at an angle relative to the longitudinal axis of bore  106  in which the terminus is mounted. 
   Turning to  FIG. 32 , an alternative terminus suitable  600  for use with the connector(s) described herein permits the desired angular movement (indicated by arrow  601 ) while providing the desired sealing of the terminus from the environment. Terminus  600  includes a pin body  602  having first and second ends  604 ,  606 . Pin body  602  includes a large diameter end portion  608  formed adjacent the first end  604  and a shaft portion  610  extending from the large diameter end portion. A longitudinally extending central opening  612  extending through pin body  602  includes a socket  614  configured to receive a ferrule  620 . Socket  614  may have a slight inward taper to facilitate press fitting ferrule  620  into the socket. As illustrated, a portion of ferrule  620  extends axially from the first end  604  of pin body  602 . A bore  622  extends longitudinally through ferrule  620  for receiving an optical fiber therethrough. In one variation, ferrule  620  is formed from a ceramic material; in other variations ferrules may be formed from glass, plastic or suitable metals. 
   Referring still to  FIG. 32 , large diameter end portion  608  includes a first fixed collar  616  formed adjacent first end  604  and a second fixed collar  618  spaced from the first fixed collar. Shaft portion  610  extends from second fixed collar  618  to second end  606  of pin body  602 . A floating seal  624  is slidably mounted on shaft portion  610  between a spring  626  and a slip collar  628 . As illustrated, slip collar  628  has a generally “C” shaped section in an axial direction. A retainer  630  such as an e-clip or snap ring is mounted in a circumferential groove  632  formed in shaft portion  610 . Retainer  630  retains floating seal  624 , spring  626  and slip collar  628  on pin body  602 . Terminus  600  is configured to be mounted in cutouts  32  formed in the forward most face  28  of plug insert  20  ( FIG. 3 ) with face  28  positioned between slip collar  628  and retainer  630  such that spring  626  pinches face  28  between the slip collar and retainer. 
     FIG. 33  is an enlarged sectional view of floating seal  24 . Floating seal  624  includes a cylindrical sidewall  636  that defines an axially extending passage  638  extending through the seal. Floating seal  624  is slidably mounted on shaft portion  610  of pin body  602  with the shaft portion extending through the seal. As illustrated, a first annular recess  640  is formed around the inside circumference of cylindrical sidewall  636  at a first end  642  of the seal. A second annular recess  644  is formed around the inside circumference of cylindrical sidewall  636  at the second end  648  of the sidewall. An annular ridge  650  extends around the inner circumference of cylindrical sidewall  636  between the first and second annular recesses  640 ,  644 , respectively. 
   Referring still to  FIG. 33 , passage  638  includes a first internal diameter d 1  across first annular recess  640 , a second internal diameter d 2  across second annular recess  644  and a diameter d 3  across passage  638  at annular ridge  650 . As illustrated, diameter d 2  is greater than diameter d 1  which in turn is greater than diameter d 3 . This configuration permits pin body  602  to rotate a limited distance relative to seal  624  around a pivot defined by ridge  650  and generally indicated at  652 . First annular recess  640  provides clearance to permit angular movement of pin body  602  around pivot  652  while second annular recess is sized to receive a resilient sealing member such as O-ring  656  ( FIG. 34 ). Also as illustrated, second annular recess  644  is includes an inwardly sloping shoulder  658  at the internal end of the recess to provide additional clearance. 
     FIG. 34  is an enlarged view of the encircled portion of  FIG. 32 . Outer and inner O-rings  654 ,  656  provide radial and axial sealing of terminus  600 . Outer O-ring  654  is positioned in a groove  660  that extends around the outside circumference of cylindrical sidewall  636  adjacent first end  642  of the seal to provide axial sealing between cylindrical sidewall  636  and the bore in which terminus  600  is mounted. Inner O-ring  654  is retained in second annular recess  644  to provide axial sealing between cylindrical sidewall  636  and shaft portion  610  as well as radial sealing between the cylindrical sidewall and slip collar  628 . O-rings  654 ,  656  are typically formed from a resilient elastomeric material such as a synthetic rubber. 
   The drawings and detailed description herein are to be regarded in an illustrative rather than a restrictive manner, and are not intended to limit the following claims to the particular forms and examples disclosed. On the contrary, further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments will be apparent to those of ordinary skill in the art. Thus, it is intended that the following claims be interpreted to embrace all such further modifications, changes, rearrangements, substitutions, alternatives, design choices, and embodiments.