Abstract:
The present invention provides a non-physical contact (non-PC) visual fault locator (VFL) coupler that functions with fewer components and reduces handling, and without ferrule-to-ferrule contact, thereby reducing endface wear degradation and other problems. Specifically, the non-PC VFL coupler incorporates an alignment sleeve retainer that includes a connector stop, such that, when a field-installable fiber optic connector engages the alignment sleeve retainer of the non-PC VFL coupler, the endfaces of the ferrules of the non-PC VFL coupler and the field-installable fiber optic connector do not physically contact one another. Both 1.25 mm and 2.5 mm versions are contemplated, among others.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to enabling equipment associated with field-installable fiber optic connectors and a related optical continuity test system (CTS). More specifically, the present invention relates to a non-physical contact (non-PC) visual fault locator (VFL) coupler and an associated method of use. The non-PC VFL coupler of the present invention allows an optical CTS to function with fewer components and reduced handling, and without ferrule-to-ferrule contact, thereby reducing endface wear degradation and other problems. 
   2. Technical Background of the Invention 
   Current installation techniques associated with field-installable fiber optic connectors involve the verification of optical continuity using an optical CTS, as described in detail in U.S. Pat. No. 6,816,661 (Barnes, et al.), which is incorporated in-full by reference herein. Such techniques use a visual laser source, one or more jumpers coupled to the visual laser source, and one or more couplers coupled to the one or more jumpers to verify optical fiber contact in a mechanical splice joint. These couplers are generally connector-type specific (e.g., single fiber 1.25 mm and 2.5 mm or multi-fiber ferrules, etc.). There are, however, commercially-available universal couplers that adapt 2.5 mm VFL ports to 1.25 mm connectors, for example. For the most part, these techniques work well, but are somewhat cumbersome due to the number of components involved and the need to periodically replace the worn out jumpers. To complete a connector termination using an existing optical CTS, a VFL is attached to a jumper, the jumper is then attached to a coupler, and the coupler then accepts a field-installable fiber optic connector. An installation tool is used to accept/align/secure the field and factory optical fibers in the mechanical splice joint. The existing optical CTS requires that the ferrule endfaces remain in physical contact (PC) for proper operation. This ferrule endface PC requirement dictates that the coupler holds the ferrule endfaces together, in a robust geometry, and makes endface wear degradation an issue. 
   Specifically, Barnes et al. discloses methods for validating the continuity of one or more optical fibers upon which a fiber optic connector is mounted. Generally, the fiber optic connector is mounted upon an optical field fiber by actuating a cam mechanism to secure the optical field fiber in a position relative to an optical fiber stub. If subsequent testing indicates that the continuity of the optical field fiber and the optical fiber stub is unacceptable, the cam mechanism may be deactuated, the optical field fiber may be repositioned and the cam mechanism may be reactuated without having to remove and replace the fiber optic connector. In order to determine if continuity has been established between the optical field fibers and respective optical fiber stubs, a method is also disclosed that introduces light into at least one of each pair of optical field fibers and optical fiber stubs and that only secures the position of each optical field fiber relative to the respective optical fiber stub once the glow associated with each pair of optical field fibers and optical fiber stubs appreciably dissipates, which dissipation indicates the establishment of acceptable continuity. 
   Thus, as of yet, there is an unresolved need for a non-PC VFL coupler that functions with fewer components and reduces handling, and without ferrule-to-ferrule contact, thereby reducing endface wear degradation and other problems. 
   SUMMARY OF THE INVENTION 
   In various embodiments, the present invention provides a non-PC VFL coupler that functions with fewer components and reduces handling, and without ferrule-to-ferrule contact, thereby reducing endface wear degradation and other problems. Specifically, the non-PC VFL coupler incorporates an alignment sleeve retainer that includes a connector stop, such that, when a field-installable fiber optic connector engages the alignment sleeve retainer of the non-PC VFL coupler, the endfaces of the ferrules of the non-PC VFL coupler and the field-installable fiber optic connector do not physically contact one another. Both 1.25 mm and 2.5 mm versions are contemplated, among others. 
   In one embodiment, the present invention provides a non-physical contact visual fault locator coupler for coupling a light source to a fiber optic connector under test without physical contact of the associated ferrules, including: an alignment sleeve retainer having an interior surface defining a bore therethrough, a light source side, and a fiber optic connector side, the fiber optic connector side of the alignment sleeve retainer including a connector stop; and a first ferrule disposed partially within the light source side of the bore of the alignment sleeve retainer; wherein the fiber optic connector side of the alignment sleeve retainer is configured to selectively engage and retain a fiber optic connector including a second ferrule, the second ferrule disposed partially within the fiber optic connector side of the bore of the alignment sleeve retainer; and wherein the connector stop of the alignment sleeve retainer is configured to prevent an endface of the second ferrule disposed partially within the fiber optic connector side of the bore of the alignment sleeve retainer from making physical contact with an endface of the first ferrule disposed partially within the light source side of the bore of the alignment sleeve retainer. 
   Optionally, the non-physical contact visual fault locator coupler also includes an alignment sleeve disposed at least partially within the bore of the alignment sleeve retainer and about the portions of the first and second ferrules disposed therein. The non-physical contact visual fault locator coupler also includes a ferrule holder having an interior surface defining a bore therethrough, a light source side, and a fiber optic connector side, the fiber optic connector side of the alignment ferrule holder configured to engage and retain the light source side of the alignment sleeve retainer, the first ferrule disposed partially within the fiber optic connector side of the bore of the ferrule holder. The non-physical contact visual fault locator coupler further includes a third ferrule disposed partially within the light source side of the bore of the ferrule holder. The light source side of the ferrule holder is configured to selectively engage and retain one or more of a jumper and a port of a visual fault locator. The non-physical contact visual fault locator coupler still further includes a bayonet disposed about the alignment sleeve retainer and the ferrule holder. Finally, the connector stop of the alignment sleeve retainer is configured to prevent the endface of the second ferrule disposed partially within the fiber optic connector side of the bore of the alignment sleeve retainer from making physical contact with the endface of the first ferrule disposed partially within the light source side of the bore of the alignment sleeve retainer and maintaining a separation distance of between about 1 μm and about 500 μm. 
   In another embodiment, the present invention provides a non-physical contact visual fault locator coupler for coupling a light source to a fiber optic connector under test without physical contact of the associated ferrules, including: an alignment sleeve retainer having an interior surface defining a bore therethrough, a light source side, and a fiber optic connector side; a first flat ferrule disposed partially within the light source side of the bore of the alignment sleeve retainer; and a ferrule holder having an interior surface defining a bore therethrough, a light source side, and a fiber optic connector side, the fiber optic connector side of the alignment ferrule holder configured to engage and retain the light source side of the alignment sleeve retainer, the first ferrule disposed partially within the fiber optic connector side of the bore of the ferrule holder; wherein the fiber optic connector side of the alignment sleeve retainer is configured to selectively engage and retain a fiber optic connector comprising a second angled physical contact (APC) ferrule, the second ferrule disposed within the fiber optic connector side of the bore of the alignment sleeve retainer; and wherein a portion of the APC ferrule endface contacts a portion of the UPC ferrule to generate an air gap at the ferrule-to-ferrule interface. The air gap prevents fiber-to-fiber contact and is accounted for in the setup of the VFL. Optionally, the non-physical contact visual fault locator coupler includes an alignment sleeve disposed at least partially within the bore of the alignment sleeve retainer and about the portions of the first and second ferrules disposed therein. The non-physical contact visual fault locator coupler also includes a third ferrule disposed partially within the light source side of the bore of the ferrule holder. The light source side of the ferrule holder is configured to selectively engage and retain one or more of a jumper and a port of a visual fault locator. The non-physical contact visual fault locator coupler may further include a bayonet disposed about the alignment sleeve retainer and the ferrule holder. The air gap provides varying separation distances at various points dependent upon the angle of the APC ferrule. 
   In a further embodiment, the present invention provides method for coupling a light source to a fiber optic connector including any type of ferrule under visual fault test or the like, including: mating the fiber optic connector including the ferrule with a coupler including a ferrule and a connector stop; wherein the connector stop of the coupler is configured to prevent an endface of the ferrule of the fiber optic connector from making physical contact with an endface of the ferrule of the coupler, while allowing the endface of the ferrule of the fiber optic connector to be optically coupled with the endface of the ferrule of the coupler. Preferably, the connector stop comprises a shoulder structure manufactured into the outside surface of the coupler. Optionally, the connector stop comprises a collar disposed wholly or partially within an inside portion of the coupler. Another method of the present invention provides coupling a light source to a fiber optic connector including an APC ferrule under visual fault test or the like, including: mating the fiber optic connector including the APC ferrule with a coupler including a flat ferrule, such that an air gap is generated at the mating interface as a portion of the APC ferrule contacts the flat ferrule endface. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of one embodiment of the non-PC VFL coupler of the present invention, specifically a 1.25 mm version. 
       FIG. 2  is a cross-sectional view of the non-PC VFL coupler of  FIG. 1 . 
       FIG. 3  is a cross-sectional view of the non-PC VFL coupler of  FIG. 1  engaged with a compatible field-installable fiber optic connector, the endfaces of the ferrules of the non-PC VFL coupler and the field-installable fiber optic connector not physically contacting one another. 
       FIG. 4  is a perspective view of another embodiment of the non-PC VFL coupler of the present invention, specifically a 2.5 mm version. 
       FIG. 5  is a cross-sectional view of the non-PC VFL coupler of  FIG. 4 . 
       FIG. 6  is a cross-sectional view of the non-PC VFL coupler of  FIG. 4  engaged with a compatible field-installable fiber optic connector, the endfaces of the ferrules of the non-PC VFL coupler and the field-installable fiber optic connector not physically contacting one another. 
       FIG. 7  is a cross-sectional view of a non-PC VFL coupler engaged with a compatible field-installable fiber optic connector including a 1.25 mm APC ferrule, the endface portions about the optical fiber of the flat ferrule of the non-PC VFL coupler and the APC ferrule not physically contacting one another. 
       FIG. 8  is a cross-sectional view of a non-PC VFL coupler engaged with a compatible field-installable fiber optic connector including a 2.5 mm APC ferrule, the endface portions about the optical fiber of the flat ferrule of the non-PC VFL coupler and the APC ferrule not physically contacting one another. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Reference is now made to preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Whenever possible, like reference numbers are used to refer to the same or like components/parts. It should be noted that the features of the non-PC VFL coupler disclosed could be applied equally to the receptacle or plug portion of a receptacle and plug assembly. Thus, the generic term “connector” is used herein. Although specific connector types and ferrule sizes are described herein, it is contemplated that any type, number and ferrule size may be used in the present invention. 
     FIGS. 1 and 2  illustrate one embodiment of the non-PC VFL coupler  10  of the present invention, specifically a 1.25 mm version. The non-PC VFL coupler  10  includes a substantially-cylindrical or annular ferrule holder  12  that is configured to engage and retain a 1.25 mm ferrule  14  on one end  15  and a larger 2.5 mm ferrule  16  on the other end  17 . The first ferrule  14  is disposed partially within a corresponding opening formed by the first end  15  of the ferrule holder  12  and the second ferrule  16  is disposed partially within a corresponding opening formed by the second end  17  of the ferrule holder  12 . The ferrule holder  12  may be manufactured from a substantially-rigid material, such as a plastic, metal or ceramic material. Optionally, the second end  17  of the ferrule holder  12  is keyed, such that it engages a VFL port or the like, as described in greater detail below. In alternative embodiments, the alignment member may also be keyed. 
   A substantially-cylindrical or annular alignment sleeve retainer  18 , also referred to herein as an “alignment member”, is configured to engage and retain the first end  15  of the ferrule holder  12 , as well as a ferrule alignment sleeve  19  disposed within a bore  26  formed therethrough. It should be noted that this ferrule alignment sleeve  19  is optional, and the alignment sleeve retainer  18  may alternatively be manufactured with a precision bore to provide adequate ferrule alignment. The first ferrule  14  is disposed partially within the ferrule alignment sleeve  19 . The alignment sleeve retainer  18  is manufactured from a substantially-rigid material, such as a plastic or metal material. A bayonet  20  is selectively disposed about the alignment sleeve retainer  18 , the ferrule holder  12 , and the other components of the non-PC VFL coupler  10 . Preferably, the bayonet  20  is internally threaded and engages the VFL port or the like. The ferrule holder  12  is manufactured from a substantially-rigid material, such as a plastic or metal material. Within the non-PC VFL coupler  10 , an optical fiber  21  ( FIG. 2 ) optically couples the first ferrule  14  to the second ferrule  16 . In alternative embodiments, ferrules  14  and  16  may be similar. 
   The second end  17  of the ferrule holder  12 , the second ferrule  16 , and the bayonet  20  are collectively configured to engage and optically mate with a VFL port  24  of a CTS system (not illustrated) or the like, either directly or through a jumper (not illustrated) or the like. Likewise, referring to  FIG. 3 , the alignment sleeve retainer  18  is configured to engage and retain the end of a connector  30 , such as a 1.25 mm ferruled connector, as in the present embodiment, a 2.5 mm ferruled connector, a multi-fiber connector, etc. The end of the connector  30  includes a 1.25 mm ferrule  32 . This third ferrule  32  is disposed partially within the ferrule alignment sleeve  19  of the coupler  10  when the alignment sleeve retainer  18  and connector  30  are engaged. Advantageously, a connector stop  22  manufactured into the outside surface of the alignment sleeve retainer  18  contacts the end of the connector housing  30  and controls the depth of penetration of the third ferrule  32  into the ferrule alignment sleeve  19 . Preferably, the connector stop  22  brings the endfaces of the first ferrule  14  and the third ferrule  32  into close proximity, but does not allow the endfaces to make PC. Ideally, the separation of the endfaces of the first ferrule  14  and the third ferrule  32  is on the order of micrometers (microns). 
   The connector  30  also includes a field fiber lead-in tube  34  and a plurality of other components, not directly relevant to the discussion herein. All of the components of the coupler  10  and connector  30  may be press-fit together, joined using an adhesive, integrally formed, etc. 
     FIGS. 4 and 5  illustrate another embodiment of the non-PC VFL coupler  50  of the present invention, specifically a 2.5 mm version. The non-PC VFL coupler  50  includes a substantially-cylindrical or annular ferrule holder  52  that is configured to engage and retain a 2.5 mm ferrule  54  on one end  55  and a 2.5 mm ferrule  56  on the other end  57 . The first ferrule  54  is disposed partially within a corresponding opening formed by the first end  55  of the ferrule holder  52  and the second ferrule  56  is disposed partially within a corresponding opening formed by the second end  57  of the ferrule holder  52 . The ferrule holder  52  is manufactured from a substantially-rigid material, such as a plastic or metal material. Optionally, the second end  57  of the ferrule holder  52  is keyed, such that it engages a VFL port or the like, as described in greater detail below. 
   A substantially-cylindrical or annular alignment sleeve retainer  58  is configured to engage and retain the first end  55  of the ferrule holder  52 , as well as a ferrule alignment sleeve  59  disposed within a bore  66  formed therethrough. Again, it should be noted that this ferrule alignment sleeve  59  is optional, and the alignment sleeve retainer  58  may alternatively be manufactured with a precision bore to provide adequate ferrule alignment. The first ferrule  54  is disposed partially within the ferrule alignment sleeve  59 . The alignment sleeve retainer  58  is manufactured from a substantially-rigid material, such as a plastic or metal material. A bayonet  60  is selectively disposed about the alignment sleeve retainer  58 , the ferrule holder  52 , and the other components of the non-PC VFL coupler  50 . Preferably, the bayonet  60  is internally threaded and engages the VFL port or the like. The ferrule holder  52  is manufactured from a substantially-rigid material, such as a plastic or metal material. Within the non-PC VFL coupler  50 , an optical fiber  61  ( FIG. 5 ) optically couples the first ferrule  54  to the second ferrule  56 . In alternative embodiments, ferrules  54  and  56  may be similar. 
   The second end  57  of the ferrule holder  52 , the second ferrule  56 , and the bayonet  60  are collectively configured to engage and optically mate with a VFL port  64  of a CTS system (not illustrated) or the like, either directly or through a jumper (not illustrated) or the like. Likewise, referring to  FIG. 6 , the alignment sleeve retainer  58  is configured to engage and retain the end of a connector  70 , such as a 1.25 mm ferruled connector, a 2.5mm ferruled connector, as in the present embodiment or, a multi-fiber connector, etc. The end of the connector  70  includes a 2.5 mm ferrule  72 . This third ferrule  72  is disposed partially within the ferrule alignment sleeve  59  of the coupler  50  when the alignment sleeve retainer  58  and connector  70  are engaged. Advantageously, a connector stop  62  manufactured into the outside surface of the alignment sleeve retainer  58  contacts the end of the connector  70  and controls the depth of penetration of the third ferrule  72  into the ferrule alignment sleeve  59 . Preferably, the connector stop  62  brings the endfaces of the first ferrule  54  and the third ferrule  72  into close proximity, but does not allow the endfaces to make PC. Ideally, the separation of the endfaces of the first ferrule  54  and the third ferrule  72  is on the order of micrometers (microns). 
   The connector  70  also includes a field fiber lead-in tube  74  and a plurality of other components, not directly relevant to the discussion herein. All of the components of the coupler  50  and connector  70  may be press-fit together, joined using an adhesive, integrally formed, etc. 
     FIG. 7  illustrates another embodiment of the non-PC VFL coupler  10  of the present invention, specifically a 1.25 mm version. The non-PC VFL coupler  10  includes a substantially-cylindrical or annular ferrule holder  12  that is configured to engage and retain a 1.25 mm flat ferrule  14  on one end  15 , and a larger 2.5 mm ferrule  16  on the other end  17 . The flat ferrule  14  is disposed partially within a corresponding opening formed by the first end  15  of the ferrule holder  12  and the second ferrule  16  is disposed partially within a corresponding opening formed by the second end  17  of the ferrule holder  12 . The ferrule holder  12  is manufactured from a substantially-rigid material, such as a plastic, metal or ceramic material. Optionally, the second end  17  of the ferrule holder  12  is keyed, such that it engages a VFL port or the like, as described in greater detail below. 
   A substantially-cylindrical or annular alignment sleeve retainer  18  is configured to engage and retain the first end  15  of the ferrule holder  12 , as well as a ferrule alignment sleeve  19  disposed within a bore  26  formed therethrough. It should be noted that this ferrule alignment sleeve  19  is optional, and the alignment sleeve retainer  18  may alternatively be manufactured with a precision bore to provide adequate ferrule alignment. The flat ferrule  14  is disposed partially within the ferrule alignment sleeve  19 . A bayonet  20  is selectively disposed about the alignment sleeve retainer  18 , the ferrule holder  12 , and the other components of the non-PC VFL coupler  10 . Preferably, the bayonet  20  is internally threaded and engages the VFL port or the like. Within the non-PC VFL coupler  10 , an optical fiber  21  optically couples the first ferrule  14  to the second ferrule  16 . 
   The second end  17  of the ferrule holder  12 , the second ferrule  16 , and the bayonet  20  are collectively configured to engage and optically mate with a VFL port  24  of a CTS system (not illustrated) or the like, either directly or through a jumper (not illustrated) or the like. The alignment sleeve retainer  18  is configured to engage and retain the end of a connector  30 , such as a 1.25 mm APC ferruled connector, as in the present embodiment, a 2.5 mm APC ferruled connector, a multi-fiber APC connector, etc. The end of the connector  30  includes an APC ferrule  32 . This third ferrule  32  is disposed partially within the ferrule alignment sleeve  19  of the coupler  10  when the alignment sleeve retainer  18  and connector  30  are engaged. A portion of the APC ferrule endface contacts a portion of the flat ferrule endface and generates an air gap therebetween such that the endface portions of the ferrules about the optical fiber bore are not in physical contact, thus preventing endface wear and degradation. The air gap is shown exaggerated for clarity. In other words, the physical stop is provided by mating a flat ferrule and an APC ferrule. The resulting air gap at the ferrule-to-ferrule interface is accounted for by the operator or VFL during a continuity test. Preferably, the angle of the APC ferrule endface brings the endfaces of the first ferrule  14  and the third ferrule  32  into close proximity, but does not allow the fiber presenting portions to make PC. Ideally, the separation of the endfaces of the first ferrule  14  and the third ferrule  32  is on the order of micrometers (microns), and varies along the air gap length. In alternative embodiments, the coupler ferrule may be an APC ferrule and the connector ferrule under test a flat ferrule, still producing an air gap therebetween. In another alternative embodiment, the coupler ferrule and the connector ferrule that optically mates with the coupler ferrule may both be APC type ferrule having non-complimentary angles or oriented such that an air gap is formed therebetween. 
     FIG. 8  illustrates another embodiment of the non-PC VFL coupler  50  of the present invention, specifically a 2.5 mm version. The non-PC VFL coupler  50  includes a substantially-cylindrical or annular ferrule holder  52  that is configured to engage and retain a 2.5 mm ferrule  54  on one end  55  and a 2.5 mm ferrule  56  on the other end  57 . The first ferrule  54  is disposed partially within a corresponding opening formed by the first end  55  of the ferrule holder  52  and the second ferrule  56  is disposed partially within a corresponding opening formed by the second end  57  of the ferrule holder  52 . Optionally, the second end  57  of the ferrule holder  52  is keyed, such that it engages a VFL port or the like, as described in greater detail below. 
   A substantially-cylindrical or annular alignment sleeve retainer  58  is configured to engage and retain the first end  55  of the ferrule holder  52 , as well as a ferrule alignment sleeve  59  disposed within a bore  66  formed therethrough. Again, it should be noted that this ferrule alignment sleeve  59  is optional, and the alignment sleeve retainer  58  may alternatively be manufactured with a precision bore to provide adequate ferrule alignment. The first ferrule  54  is disposed partially within the ferrule alignment sleeve  59 . A bayonet  60  is selectively disposed about the alignment sleeve retainer  58 , the ferrule holder  52 , and the other components of the non-PC VFL coupler  50 . Preferably, the bayonet  60  is internally threaded and engages the VFL port or the like. Within the non-PC VFL coupler  50 , an optical fiber  61  optically couples the first ferrule  54  to the second ferrule  56 . 
   The second end  57  of the ferrule holder  52 , the second ferrule  56 , and the bayonet  60  are collectively configured to engage and optically mate with a VFL port  64  of a CTS system (not illustrated) or the like, either directly or through a jumper (not illustrated) or the like. Likewise, the alignment sleeve retainer  58  is configured to engage and retain the end of a connector  70 , such as a 1.25 mm APC ferruled connector, a 2.5 mm APC ferruled connector, as in the present embodiment or, a multi-fiber APC connector, etc. The end of the connector  70  includes a 2.5 mm APC ferrule  72 . This third ferrule  72  is disposed partially within the ferrule alignment sleeve  59  of the coupler  50  when the alignment sleeve retainer  58  and connector  70  are engaged. A portion of the APC ferrule endface contacts a portion of the flat ferrule endface and generates an air gap therebetween such that the endface portions of the ferrules about the optical fiber bore are not in physical contact, thus preventing endface wear and degradation. The air gap is shown exaggerated for clarity. In other words, the physical stop is provided by mating a flat ferrule and an APC ferrule. The resulting air gap at the ferrule-to-ferrule interface is accounted for by the operator or VFL during a continuity test. Preferably, the angle of the APC ferrule endface brings the endfaces of the first ferrule  54  and the third ferrule  72  into close proximity, but does not allow the fiber presenting portions to make PC. Ideally, the separation of the endfaces of the first ferrule  54  and the third ferrule  72  is on the order of micrometers (microns). In alternative embodiments, the coupler ferrule may be an APC ferrule and the connector ferrule under test a flat ferrule, still producing an air gap therebetween. 
   Although the non-PC VFL coupler of the present invention has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present invention and are intended to be covered by the following claims.