OF FIBER OPTIC FERRULE

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of U.S. Patent Application Serial No. 62/145,656, filed on April 10, 2015, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Certain types of fiber optic ferrules, such as MT ferrules, have fiber holes for securing optical fibers therein. Signal transmission through the optical fibers can depend on precise coaxial alignment of the fibers corresponding to mating connectors. Precise positioning of the optical fibers is dependent upon precise positioning of the fiber holes through the ferrules. The angles of the fiber holes also affect positioning precision, particularly when polishing is taken into consideration. It is therefore necessary to accurately position the centers of fiber holes, at which optical fiber cores are located, to achieve low loss of signal transmission. A process of measuring the true positions and angles of the fiber holes on a ferrule is standard for ferrule manufacturers and cable assembly manufacturers.

[0003] In certain examples, the fiber hole positions and angles are determined with respect to guide pin holes formed in a ferrule (i.e., the guide pin holes are used as reference points). However, the guide pin holes of a ferrule are often angled or tilted in the ferrule, and, thus, the position of each guide pin hole can change as the end face of the ferrule is polished. The offset of the guide pin hole position on the end face of the ferrule can cause inaccurate measurement of a position of each fiber hole of the ferrule.

[0004] In certain examples, an interferometer is used to evaluate an end face of a multi-fiber ferrule. Examples of using an interferometer are disclosed in U.S. Patent No. 6,215,555, the disclosure of which is incorporated herein by reference in its entirety. For example, a system for evaluating a ferrule end face includes a reference guide pin having polished fiat end surface oriented at a predetermined angle relative to a longitudinal axis of the reference guide pin. The reference guide pin is inserted into a guide pin hole of the ferrule, and the interferometer is first focused onto the ferrule end face. The ferrule end face is tipped and tilted to minimize a viable fringe density on the ferrule end face. The interferometer then acquires the interferogram data and produces an uncalibrated profile of the connector end surface. The interferometer then is focused on the end surface of the reference guide pin and acquires its interferogram data, and then computes a profile of the end surface. The profiles of the ferrule end face and the end surface of the reference guide pin are combined to provide a calibrated profile of the ferrule end face.

[0005] In certain examples, a measurement pin is employed to determine an orientation of an axis of a guide pin hole defined by a multi-fiber ferrule. Examples of using a measurement pin are disclosed in U.S. Patent No. 6,705,767, the disclosure of which is incorporated herein by reference in its entirety. For example, a measurement pin is positioned in the guide pin hole with a first end disposed proximate the end face of the ferrule. The first end of the measurement pin functions as a reference plane, and the orientation of the axis of the guide pin hole is determined based upon the predetermined angle between the axis of the guide pin hole and the reference plane. Further, a plane defined by at least a portion of the end face of the ferrule is measured. The end face angle is determined based upon the angular difference between the reference plane and the plane defined by the end face of the ferrule.

[0006] However, the reference guide pin as illustrated in US 6,215,555 or the measurement pin as illustrated in US 6,705,767 is a separate piece from the

interferometer and the ferrule, and thus a special tool is required to insert, or remove, the reference guide pin into, or from, the guide pin hole of the ferrule. Further, the end face of the reference guide pin or measurement pin is not large enough to provide a clear and accurate point of reference in evaluating the ferrule end face.

SUMMARY

[0007] In general terms, this disclosure relates to a system for measuring a guide pin hole angle of a fiber optic ferrule. In one possible configuration and by non-limiting example, the system includes a reference pin assembly having a floating reference pin configured to be inserted into a guide pin hole of a ferrule, and a reference plane extending from the reference pin. The reference plane is arranged such that both of the reference plane and the ferrule end face are at least partially detected together by a measuring device.

[0008] The present disclosure is generally directed to a system for measuring physical characteristics of a guide pin hole defined in a fiber optic ferrule. In certain examples, the physical characteristics relate to an angle of the guide pin hole relative to a reference structure. In some embodiments, the measured characteristic of the guide pin hole is defined as an angle of an axis of the guide pin hole relative to an end face of the ferrule. The angle of the guide pin hole may include an angular position of the guide pin hole axis relative to a first axis (e.g., X-axis) and an angular position of the guide pin hole axis relative to a second axis (e.g., Y-axis). The axes X and Y can be perpendicular to one another and parallel to the end face of the ferrule. The axes X and Y can intersect at the axis of the guide pin hole.

[0009] The system in accordance with the present disclosure may include a reference pin assembly configured to be used with a measuring device, such as an interferometer. The reference pin assembly may include a reference pin and a reference plane. The reference pin is fioatingly secured to the measuring device and configured to be inserted into the guide pin hole as the ferrule is mounted to the measuring device. In some examples, the reference pin extends along a Z-axis and is configured to be slightly displaceable in an X-axis and a Y-axis and able to pivot along the X-axis and the Y-axis. The reference plane is configured to radially extend from the reference pin and configured to be arranged adjacent the ferrule end face when the ferrule is mounted to the measuring device. In some embodiments, the reference plane is arranged to be substantially the same depth of focus as the ferrule end face when scanned by the measuring device. The reference plane may provide a fiat and calibrated reference face configured to be scanned, together with at least a portion of the ferrule end face (e.g., at least a portion of the ferrule end face adjacent fiber holes of the ferrule) by the measuring device. The measuring device can then scan both of the reference plane and the ferrule end face and analyzes an angle of the guide pin hole axis relative to the ferrule end face, which can be reduced to two angular position components about X-axis and Y-axis. [0010] Various aspects are described in this disclosure, which include, but are not limited to, the following aspects.

[0011] One aspect relates to a reference pin assembly for evaluating at least one of a first guide pin hole and a second guide pin hole of a fiber optic ferrule. The system may include a first reference pin and a first reference plane. The first reference pin is floatingly secured to a measuring device and configured to be inserted into the first guide pin hole as the ferrule is mounted to the measuring device. The first reference plane is connected to the first reference pin and configured to be arranged adjacent an end face of the ferrule when the ferrule is mounted to the measuring device.

[0012] Another aspect relates to a system for evaluating a guide pin hole of a fiber optic ferrule. The system may include a measuring device and a reference pin assembly. The fiber optic ferrule may include a ferrule body defining an end face. The ferrule body may include at least one fiber hole configured to receive at least one optical fiber, and at least one guide pin hole configured to receive at least one guide pin, to align the ferrule body with another ferrule body. The measuring device is configured to evaluate the guide pin hole of the ferrule. The measuring device may include a ferrule mounting head to which the ferrule is secured during measurement. The reference pin assembly may include a first reference pin and a first reference plane. The first reference pin is floatingly secured to the ferrule mounting head of the measuring device and configured to be inserted into the guide pin hole as the ferrule is mounted to the ferrule mounting head of the measuring device. The first reference plane is connected to the first reference pin and configured to be arranged adjacent the end face of the ferrule when the ferrule is mounted to the ferrule mounting head of the measuring device.

[0013] Yet another aspect relates to a reference pin assembly for evaluating a guide pin hole of a fiber optic ferrule. The assembly may include a reference pin and a reference plane. The reference pin is floatingly secured to a measuring device and configured to be inserted into the guide pin hole as the ferrule is mounted to the measuring device. The reference plane is configured to radially extend from the reference pin and be arranged adjacent an end face of the ferrule when the ferrule is mounted to the measuring device. [0014] The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a perspective view of an example fiber optic ferrule.

[0016] FIG. 2 is a schematic view of an example system for evaluating the guide pin holes of the ferrule.

[0017] FIG. 3 is a schematic front perspective view of an example reference pin assembly that is secured to a ferrule mounting head of a measuring device.

[0018] FIG. 4 is a schematic rear perspective view of the reference pin assembly of FIG. 3.

[0019] FIG. 5 is a schematic side view of an example reference pin assembly that is movably fixed at a receptacle of the ferrule mounting head and that engages the ferrule through a ferrule mounting adapter.

[0020] FIG. 6 is a schematic top view of the ferrule mounted to the ferrule mounting head for measuring processes.

[0021] FIG. 7 is a schematic front view of the reference pin assembly engaged with the ferrule.

[0022] FIG. 8 illustrates another example of the system for evaluating the guide pin holes of the ferrule in accordance with the present disclosure.

[0023] FIG. 9 illustrates another example reference pin assembly.

[0024] FIG. 10 illustrates yet another example reference pin assembly.

[0025] FIG. 11 A illustrates an example pin shifting mechanism.

[0026] FIG. 1 IB illustrates the pin shifting mechanism in a different position.

[0027] FIG. 12A illustrates an example pin tilting mechanism.

[0028] FIG. 12B illustrates the pin tilting mechanism in a different position. DETAILED DESCRIPTION

[0029] Various embodiments will be described in detail with reference to the drawings, wherein like reference numerals represent like parts and assemblies throughout the several views.

[0030] In general, the present disclosure is directed to a system for measuring a physical characteristic of a guide pin hole defined in a fiber optic ferrule. In some embodiments, the characteristic of the guide pin hole is defined as an angle of an axis of the guide pin hole relative to an end face of the ferrule. The angle of the guide pin hole may include an angular position of the guide pin hole axis relative to a first axis (e.g., an X-axis) and an angular position of the guide pin hole axis relative to a second axis (e.g., a Y-axis). The axes X and Y can intersect one another at the guide pin hole axis and can be parallel to or coplanar with the end face of the ferrule.

[0031] The system in accordance with the present disclosure may include a reference pin assembly configured to be used with a measuring device, such as an interferometer. The reference pin assembly may include a reference pin and a reference plane. The reference pin is floatingly secured to the measuring device and configured to be inserted into the guide pin hole as the ferrule is mounted to the measuring device. In some examples, the reference pin extends in a Z-axis (i.e., the center axis of the reference pin is coaxial with the Z-axis) and is configured to be slightly displaceable in X-axis and Y-axis and rotatable about the X-axis and the Y-axis. The reference plane is configured to radially extend from the reference pin and configured to be arranged adjacent the ferrule end face when the ferrule is mounted to the measuring device. Examples of the reference plane include a reference flag or tab defining a reference plane. In some embodiments, the reference plane is arranged to be substantially the same depth of focus as the ferrule end face when scanned by the measuring device. The reference plane may provide a flat and calibrated reference face configured to be scanned, together with at least a portion of the ferrule end face (e.g., at least a portion of the ferrule end face adjacent fiber holes of the ferrule) by the measuring device. The measuring device can then scan both of the reference plane and the ferrule end face and analyzes an angle of the guide pin hole axis relative to the ferrule end face, which can be reduced to two angular position components about X-axis and Y-axis. [0032] FIG. 1 is a perspective view of an example fiber optic ferrule 100.

[0033] In some examples, the fiber optic ferrule 100 is a mechanical transfer (MT) ferrule for multi-fiber connections. The fiber optic ferrule 100 can hold optical fibers such as optical fibers that are part of a multicore fiber tape or ribbon. A fiber ribbon has a plurality of optical fibers. A polymeric matrix material that encases the optical fibers of the ribbon is removed so that the optical fibers are exposed, and the exposed optical fibers are individually inserted into fiber holes 122 through a fiber insertion opening 128 (FIG. 2) defined at the rearward end face of the ferrule 100. In some examples, the ferrule 100 has a fiber support portion therewithin that includes a plurality of grooves formed in parallel at regular pitch, each of the grooves configured to receive and support each of the optical fibers. The present disclosure primarily describes a fiber optic ferrule 100 configured to hold a plurality of optical fibers. In other examples, however, the same principles described in the present disclosure are also applicable to a fiber optic ferrule for holding a single optical fiber.

[0034] The ferrule 100 has a ferrule body 102 and an enlarged base 104. The ferrule 100 extends between a forward end 106 and a rearward end 108 and is formed in a substantially rectangular shape. The enlarged base 104 is provided at the rearward end 108 of the ferrule 100 and meets with the ferrule body 102 at a shoulder 1 18 that extends outwardly from the exterior surface of the ferrule body 102. In the illustrated example, the shoulder 1 18 extends from upper, lower and opposite side surfaces 1 10, 1 12, 1 14 and 1 16 at the ferrule body 102. In some embodiments, the shoulder 1 18 extends substantially perpendicularly or radially from the exterior surface of the ferrule body 102. The shoulder 1 18 can be substantially parallel with a forward end face 120 of the ferrule 100. A plurality of fiber holes 122 and one or more guide pin holes 124 can be defined at the ferrule end face 120.

[0035] The end face 120 is a surface of the ferrule 100 at the forward end 106. At least a portion of the end face 120 is configured to be abutted to at least a portion of an end face 120 of another ferrule 100 to perform an optical line connection. The end faces 120 of the abutting ferrules 100 are arranged opposite to each other, and alignment pins (e.g., guide pins) (not shown) are inserted into the guide pin holes 124 so as to be interposed between the opposing guide pin holes 124. [0036] Once the ferrule 100 is assembled with optical fibers and related components, the end face 120 can be polished, thereby ensuring proper fiber-to-fiber contact and reduced signal loss. The polished end surface can be alternatively referred to herein as a butt end face or a mating end face.

[0037] The fiber holes 122 are defined in the ferrule body 102 to be in

communication with a fiber insertion opening 128 (FIG. 2) defined at the rearward end of the ferrule 100. The fiber holes 122 are configured to receive optical fibers, respectively, that are inserted into the ferrule body 102 through the fiber insertion opening 128. The fiber holes 122 are open at the end face 120 of the ferrule body 102. When receiving the optical fibers, the fiber holes 122 expose tip ends of bare fibers at the end face 120. In some embodiments, the plurality of fiber holes 122 are arranged along a line at the forward end face 120 of the ferrule 100 so as to form a row of optical fibers. The plurality of fiber holes 122 can be arranged multiple lines such as two lines. Other configurations of the fiber holes 122 are also possible.

[0038] One or more guide pin holes 124 (including a first guide pin hole 124A and a second guide pin hole 124B) are provided at the forward end face 120 of the ferrule 100 to receive guide pins (not shown) that are configured to align two mating ferrules 100. Each of the guide pin holes 124 extends along a pin hole axis A _G , which is coaxial with the Z-axis in the illustrated example. The guide pin holes 124 can also be referred to herein as alignment holes. In the illustrated example, the guide pin holes 124 can be formed in a substantially circular shape in cross-section in a perpendicular direction relative to an inserting direction of a guide pin. Other cross-sectional shapes of the guide pin holes 124 are possible in other examples. In some examples, the guide pin holes 124 can extend through the ferrule 100 to open at a rearward end face 130, as well as the forward end face 120 of the ferrule 100. In the illustrated example, the ferrule 100 has two guide pin holes 124. In other examples, however, the ferrule 100 has a single guide pin hole or more than two guide pin holes.

[0039] The fiber optic ferrule 100 can be made of synthetic resin. For example, the ferrule 100 is formed by transfer molding using thermosetting resin such as an epoxy resin, injection molding using thermoplastic resin such as polyphenylene sulfide resin (PPS) or liquid crystal polymer (LCP). Other materials can be used to form the ferrule 100.

[0040] FIG. 2 is a schematic view of an example system 200 for evaluating the guide pin holes 124 of the ferrule 100. In some embodiments, the system 200 is configured to measure an angle of the axis A _R of the guide pin hole 124 relative to the end face 120 of the ferrule 100. In some embodiments, the angle of the guide pin hole axis A _R can be represented by a combination of a component of the guide pin hole axis A _R relative to X- axis (also referred to herein as X-angle) and a component of the guide pin hole axis A _R relative to Y-axis (also referred to herein as Y-angle).

[0041] In some embodiments, the system 200 includes a measuring device 204 and a reference pin assembly 202. The measuring device 204 is used to evaluate the end face 120 of the ferrule 100. The measuring device 204 includes a ferrule mounting head 206 to which the ferrule 100 is secured for measuring processes. As illustrated, the ferrule 100 is held at or adjacent the ferrule mounting head 206 with the end face 120 facing the inside of the measuring device 204 such that at least a portion of the end face 120 falls within a field of view (FOV) of a camera included in the measuring device 204. In some embodiments, the ferrule 100 is supported by a ferrule mounting adapter 210 (FIG. 5) that is configured to at least partially receive the ferrule 100 and disposed between the ferrule mounting head 206 and the enlarged base 104 of the ferrule 100.

[0042] In some embodiments, the measuring device 204 is an interferometer. The measuring device 204 can include a computer read CCD camera configured to scan at least a portion of the end face 120 of the ferrule 100, along with at least a portion of the reference pin assembly 202 (e.g., a reference plane 306 (FIG. 3) as described below. One example of the measuring device 204 is the DAIS I™ interferometer available from Data- Pixel SAS (Chavanod, France). Other interferometers can also be used for the measuring device 204 in accordance with the present disclosure.

[0043] The reference pin assembly 202 is secured to the ferrule mounting head 206 of the measuring device 204 and used to provide a point of reference for measuring the an angle of the guide pin hole axis A _R . In some embodiment, the reference pin assembly 202 is provided at a receptacle 208 defined by the ferrule mounting head 206. An example of the reference pin assembly 202 is illustrated and described with reference to FIGS. 3-7. [0044] Referring to FIGS. 3-7, an example reference pin assembly 202 is described. In particular, FIG. 3 is a schematic front perspective view of an example reference pin assembly 202 that is secured to the ferrule mounting head 206. FIG. 4 is a schematic rear perspective view of the reference pin assembly 202 of FIG. 3.

[0045] In some embodiments, the reference pin assembly 202 includes an assembly body 302, a reference pin 304, and a reference plane 306 defined by a flag or tab.

[0046] The assembly body 302 is configured to be fioatingly secured to the ferrule mounting head 206. In some embodiments, the ferrule mounting head 206 includes a support base 230, and the assembly body 302 is mounted onto the support base 230 such that at least a portion of the reference pin assembly 202 is received within the receptacle 208 of the ferrule mounting head 206.

[0047] The assembly body 302 is slightly movable relative to the support base 230 of the ferrule mounting head 206. In some embodiments, the assembly body 302 is free to move on a plane perpendicular to a reference pin axis Ap (e.g., Z-axis in this example) of the reference pin 304 (i.e., a plane defined by X-axis and Y-axis in this example).

Further, the assembly body 302 can also be free to pivot along at least one of X-axis and Y-axis. Other configurations for permitting the assembly body 302 in different directions are also possible as necessary.

[0048] In some embodiments, the assembly body 302 is fioatingly secured to the support base 230 of the ferrule mounting head 206 through an elastic coupling element 232 (FIG. 5). The elastic coupling element 232 can be disposed between the assembly body 302 and the support base 230 and allows the assembly body 302 to move relative to the support base 230. Examples of the elastic coupling element 232 include one or more spring elements.

[0049] The reference pin 304 is fixed to the assembly body 302 and extends therefrom. In the illustrated example, the reference pin 304 extends along the Z-axis away from the ferrule mounting head 206. The reference pin 304 is configured to be inserted into one of the guide pin holes 124 of the ferrule 100 when the ferrule 100 is supported by the ferrule mounting head 206 to be evaluated by the measuring device 204.

[0050] The reference plane 306 is fixed to the assembly body 302 and extends therefrom. The reference plane 306 can be defined by a flag, tab, plate, panel, or other suitable structures. In some embodiments, the reference plane 306 is secured to the assembly body 302, and perpendicular to the reference pin 304 (e.g., the reference pin axis Ap). At least a portion of the reference plane 306 is arranged outside a cylindrical boundary (e.g., imaginary boundary) defined by the exterior of the reference pin 304. In the illustrated example, the reference plane 306 has a length that extends along the X-axis along the ferrule mounting head 206.

[0051] The reference plane 306 provides a point of reference (i.e., a reference structure) to measure the angle of the guide pin hole axis A _R . The reference plane 306 is configured to be arranged adjacent the end face 120 of the ferrule 100 when the ferrule 100 is supported to the ferrule mounting head 206, such that at least a portion of the reference plane 306 and at least a portion of the end face 120 of the ferrule 100 are positioned in a field of view (FOV) (FIG. 5) of the measuring device 204. In some embodiments, the reference plane 306 is arranged to be substantially the same depth of focus as the ferrule end face 120 when scanned by the measuring device 204.

[0052] FIG. 5 is a schematic side view of an example reference pin assembly 202, illustrating that the reference pin assembly 202 is movably mounted at the receptacle 208 of the ferrule mounting head 206 and engages the ferrule 100 through a ferrule mounting adapter 210.

[0053] The ferrule mounting adapter 210 is configured to engage the ferrule 100 and support the ferrule 100 against the ferrule mounting head 206. In some embodiments, the ferrule mounting adapter 210 has an adapter body 212 extending between a first end 214 and a second end 216 along a longitudinal axis (e.g., substantially parallel with Z-axis in FIG. 3). The adapter body 212 defines an opening 218 configured to receive a ferrule body 102 of the ferrule 100 with the second end 216 abutted to the shoulder 118 of the ferrule 100. The first end 214 of the adapter body 212 is adapted to oppose to the ferrule mounting head 206 such that the end face 120 of the ferrule 100 faces the measuring device 204 (e.g., the receptacle 208 of the ferrule mounting head 206). A spacer 220 can be provided between the first end 214 of the adapter body 212 and the ferrule mounting head 206. In some examples, the adapter body 212 can be fastened or otherwise secured to the ferrule mounting head 206. [0054] In some embodiments, the ferrule mounting adapter 210 is configured to keep the ferrule 100 in place with respect to the ferrule mounting head 206 and adjacent the reference plane 306. As described above, the ferrule 100 can be biased or pressed by a force (F) against the ferrule mounting adapter 210 such that the shoulder 118 of the ferrule 100 is abutted to the second end 216 of the ferrule mounting adapter 210. Such a force (F) can be created in various manners, such as by one or more spring elements, clamping elements, magnetic elements, and any mechanisms suitable for holding the ferrule 100 in place relative to the ferrule mounting adapter 210.

[0055] As illustrated in FIG. 5, when the ferrule 100 is secured to the ferrule mounting head 206 through the ferrule mounting adapter 210, the reference pin 304 of the reference pin assembly 202 is inserted into one of the guide pin holes 124 of the ferrule 100, and the reference plane 306 is arranged adjacent the end face 120 of the ferrule 100, such that both of the end face 120 of the ferrule 100 and the reference plane 306 are at least partially scanned together by the measuring device 204. Once the end face 120 of the ferrule 100 and the reference plane 306 are scanned by the measuring device 204, an orientation of the reference plane 306 relative to the end face 120 can be determined based upon the scanned image. The detected orientation of the reference plane 306 relative to the end face 120 can be used to determine an angle of the guide pin hole 124 relative to the end face 120 of the ferrule 100. Such an angle of the guide pin hole 124 can be reduced to a combination of X-angle and Y-angle. Further, a position of the guide pin hole 124 can be eventually determined relative to other features (e.g., one or more of the fiber holes 122) on the end face 120 of the ferrule 100. Such a position of the guide pin hole 124 can also be reduced to a combination of X-axis and Y-axis components. As such, the reference plane 306 can be used as a point of reference for determining a relative position of the guide pin holes 124.

[0056] As illustrated in FIG. 5, a movement limiting mechanism 240 is provided to constrain a movement of the reference pin assembly 202 in a predetermined range. In some embodiments, the movement limiting mechanism 240 includes a first limiting element 242 provided at the receptacle 208 of the ferrule mounting head 206, and a second limiting element 244 provided at the ferrule mounting adapter 210. For example, the first and second limiting elements 242 and 244 are configured to limit a movement of the reference pin assembly 202 along the guide pin hole axis A _G (e.g., Z-axis), thereby preventing the reference pin assembly 202 from being pushed into or pulled out from the receptacle of the ferrule mounting head 206.

[0057] FIG. 6 is a schematic top view of the ferrule 100 that is mounted to the ferrule mounting head 206 for measuring processes. The ferrule mounting adapter 210 is not shown for clarity.

[0058] FIG. 7 is a schematic front view of the reference pin assembly 202 engaged with the ferrule 100. As shown, the reference plane 306 includes one or more reference marks 308 used to provide addition information about the guide pin holes 124 and/or the fiber holes 122. In some examples, the reference marks 308 provide a point of reference to determine a position of the fiber holes 122 and/or the guide pin holes 124 with respect to a predetermined structure. Examples of the predetermined structure include one or more fiber positions and/or other features of the ferrule 100. Such a position of the fiber holes 122 and/or the guide pin holes 124 can be reduced to a combination of X-axis position components and Y-axis position components.

[0059] Referring again to FIG. 1, the ferrule 100 includes two guide pin holes, such as a first guide pin hole 124A and a second guide pin hole 124B. The guide pin holes 124A and 124B can be evaluated, respectively, by engaging the reference pin assembly 202 with each of the guide pin holes 124A and 124B. For example, as illustrated in FIG. 5, the reference pin assembly 202 is engaged with the first guide pin hole 124A to measure an angle of the first guide pin hole 124A relative to the end face 120 of the ferrule 100. To measure an angle of the second guide pin hole 124B, the ferrule 100 is rotated 180 degrees and engaged with the reference pin assembly 202 so that the reference pin 304 of the reference pin assembly 202 is inserted into the second guide pin hole 124B. Then, the same processes are repeated to measure the angle of the second guide pin hole 124B relative to the end face 120 of the ferrule 100 as performed with the first guide pin hole 124A.

[0060] Referring to FIGS. 8-10, other embodiments of the reference pin assembly 202 are illustrated and described.

[0061] FIG. 8 illustrates another example of the system 200 for evaluating the guide pin holes 124 of the ferrule 100 in accordance with the present disclosure. In this example, the system 200 includes a pair of the reference pin assemblies 202. For example, the system 200 includes a first reference pin assembly 202A and a second reference pin assembly 202B. Each of the first and second reference pin assemblies 202A and 202B is the same as the reference pin assembly 202 as described above with reference to FIGS. 2-7. Thus, the description of the reference pin assembly 202 is incorporated by reference for each of the first and second reference pin assemblies 202A and 202B. The same reference numbers are used with alphabetical suffix, either A or B, in FIG. 8.

[0062] In some embodiments, the first and second reference pin assemblies 202A and 202B are identically configured. The first and second reference pin assemblies 202A and 202B are fioatingly mounted to the ferrule mounting head 206 in the same manner as described above. However, the first and second reference pin assemblies 202A and 202B are arranged and disposed symmetrically in the ferrule mounting head 206 such that the first reference pin assembly 202A is engaged with the first guide pin hole 124A and the second reference pin assembly 202B is engaged with the second guide pin hole 124B when the ferrule 100 is secured to the ferrule mounting head 206 for measuring processes. As the first and second reference pin assemblies 202A and 202B are not physically connected, the first and second reference pin assemblies 202A and 202B can independently move relative to the ferrule mounting head 206.

[0063] In some embodiments, at least a portion of the first and second reference pin assemblies 202A and 202B are simultaneously scanned together with at least a portion of the end face 120 of the ferrule 100 by the measuring device 204, and, therefore, the first and second guide pin holes 124A and 124B can be evaluated at the same time. The measuring processes can generate two sets of data, one of which relates to the first guide pin hole 124A that is evaluated with the first reference pin assembly 202 A, and the other of which relates to the second guide pin hole 124B that is evaluated with the second reference pin assembly 202B.

[0064] FIG. 9 illustrates another example reference pin assembly 320. In this example, the reference pin assembly 320 includes a first body 322, a first reference pin 324, a second body 326, a second reference pin 328, a connecting element 330, and a reference plane 332. [0065] In this example, the first reference pin 324 and the second reference pin 328 are rigidly connected through the connecting element 330. In some embodiments, the reference plane 332 is fixed to the connecting element 330 to be provided between the first and second reference pins 324 and 328.

[0066] The first body 322 is similarly configured as the assembly body 302. In particular, the first body 322 is floatingly secured to the ferrule mounting head 206 similarly to the assembly body 302. The description of the assembly body 302 and its associated structure is incorporated by reference for the first body 322, and the description of the first body 322 is omitted for brevity purposes.

[0067] The first reference pin 324 is similarly configured to the reference pin 304. In particular, the first reference pin 324 is fixed to the first body 322 and extends therefrom to be inserted into the first guide pin hole 124A of the ferrule 100 when the ferrule 100 is supported by the ferrule mounting head 206. The description of the reference pin 304 and its associated structure is incorporated by reference for the first reference pin 324, and the description of the first reference pin 324 is omitted for brevity purposes.

[0068] The second body 326 is configured to hold the second reference pin 328 such that the second reference pin 328 is inserted into the second guide pin hole 124B of the ferrule 100 when the ferrule 100 is supported by the ferrule mounting head 206. The second body 326 is connected to the first body 322 through the connecting element 330. In some embodiments, the first and second bodies 322 and 326 are inflexibly connected by the connecting element 330.

[0069] The reference plane 332 is functionally the same as the reference plane 306. In some embodiments, the reference plane 332 is fixed to the connecting element 330. In other embodiments, the reference plane 332 is integrally formed with the connecting element 330 and functions as the connecting element 330.

[0070] FIG. 10 illustrates yet another example reference pin assembly 340. In this example, the reference pin assembly 340 includes a first body 342, a first reference pin 344, a second body 346, a second reference pin 348, a connecting element 350, and a reference plane 352.

[0071] In this example, the first and second reference pins 344 and 348 are flexibly connected through the connecting element 350. The reference plane 352 is arranged between the first and second reference pins 344 and 348. In some embodiments, the reference plane 352 is secured to the connecting element 350 between the first and second reference pins 344 and 348. Examples of the connecting element 350 include spring elements, rubbers, and other flexible materials. In this configuration, each of the first and second reference pins 344 and 348 is at least partially movable with some degree of freedom but is constrained by the connecting element 350.

[0072] In other embodiments, the connecting element 350 is configured to provide no constraint to the first and second reference pins 344 and 348. For example the connecting element 350 is selected to allow each of the first and second reference pins 344 and 348 to be at least partially freely movable without creating any force between the first and second reference pins 344 and 348.

[0073] The first body 342, the first reference pin 344, the second body 346, the second reference pin 348, the connecting element 350, and the reference plane 352 can be configured similarly to the first body 322, the first reference pin 324, the second body 326, the second reference pin 328, the connecting element 330, and the reference plane 332, respectively. Thus, the description of the first body 322, the first reference pin 324, the second body 326, the second reference pin 328, the connecting element 330, and the reference plane 332 is incorporated by reference for the first body 342, the first reference pin 344, the second body 346, the second reference pin 348, the connecting element 350, and the reference plane 352.

[0074] FIGS. 11 A and 1 IB illustrate an example pin shifting mechanism 400. The pin shifting mechanism 400 is configured to shift the reference pin 304 in opposite directions within the associated guide pin hole 124 of the ferrule 100.

[0075] Where the reference pin 304 is dimensioned to have a diameter exactly identical to a diameter of the guide pin hole 124, the reference pin 304 can be

consistently positioned relative to the guide pin hole 124 when the reference pin 304 is inserted into the guide pin hole 124. Further, where the reference pin 304 is dimensioned to have a diameter slightly larger than a diameter of the guide pin hole 124, the reference pin 304 is interference-fitted into the guide pin hole 124 and can remain still with respect to the guide pin hole 124. In these configurations, the reference pin assembly 202 can provide a consistent point of reference for measuring an angle of the guide pin hole 124 relative to the end face 120 of the ferrule 100.

[0076] However, in some embodiments, the reference pin 304 can have a diameter smaller than a diameter of the guide pin hole 124 of the ferrule 100. In this case, the reference pin 304 can move within the guide pin hole 124 and fails to provide a consistent point of reference. The pin shifting mechanism 400 is used to improve the measurement of the angle of the guide pin hole 124.

[0077] The pin shifting mechanism 400 is configured to hold the reference pin 304 within the guide pin hole 124 so that an angle of the guide pin hole 124 is accurately measured by scanning the reference plane 306 and the end face 120 of the ferrule 100. In some embodiments, the pin shifting mechanism 400 operates to selectively bias the reference pin 304 in opposite directions within the guide pin hole 124. For example, as shown in FIG. 1 1 A, the pin shifting mechanism 400 operates to move the reference pin 304 in a first direction Dl (e.g., a direction perpendicular to the guide pin hole axis A _G ) so that the reference pin 304 (and thus the reference pin assembly 202) is slightly forced in the first direction Dl to settle within the guide pin hole 124. As illustrated in FIG. 11 A, the reference pin 304 is abutted with an inner surface of the guide pin hole 124 in the first direction Dl . Further, as shown in FIG. 1 IB, the pin shifting mechanism 400 also operates to move the reference pin 304 in a second direction D2 opposite to the first direction Dl so that the reference pin 304 (and thus the reference pin assembly 202) is slightly forced in the second direction D2 to settle within the guide pin hole 124. As illustrated in FIG. 1 IB, the reference pin 304 is abutted with the inner surface (i.e., the other side of the inner surface than shown in FIG. 1 1 A) of the guide pin hole 124 in the second direction Dl . In some examples, the first and second directions Dl and D2 are arranged along the X-axis. In other examples, the first and second directions Dl and D2 are arranged along the Y-axis. In yet other examples, the first and second directions Dl and D2 are arranged along any direction perpendicular to the Z-axis.

[0078] The pin shifting mechanism 400 can be configured in various manners. In some embodiments, the pin shifting mechanism 400 includes one or more spring elements to selectively bias the reference pin 304 in the first and second directions Dl and D2. In other embodiments, the pin shifting mechanism 400 uses a magnetic force to selectively shift the reference pin 304 within the guide pin hole 124. In yet other embodiments, the pin shifting mechanism 400 employs a motorized system to move the reference pin 304. In yet other embodiments, the pin shifting mechanism 400 can use gravity to move the reference pin 304 in either of the first and second directions Dl and D2 when such a direction is directed toward the ground.

[0079] The measuring device 204 operates to scan the reference plane 306 and the end face 120 when the reference pin 304 is biased in the first direction Dl and when the reference pin 304 is biased in the second direction D2. In some embodiments, if the two angles detected in the two positions are different, the angle values can be averaged to provide a single measurement.

[0080] FIGS. 12A and 12B illustrate an example pin tilting mechanism 420. The pin tilting mechanism 420 is configured to tilt the reference pin 304 in opposite rotations within the associated guide pin hole 124 of the ferrule 100. Similarly to the pin shifting mechanism 400, the pin tilting mechanism 420 is used to improve the measurement of the angle of the guide pin hole 124 when the reference pin 304 can have a diameter smaller than a diameter of the guide pin hole 124 of the ferrule 100.

[0081] The pin tilting mechanism 420 is configured to hold the reference pin 304 within the guide pin hole 124 and selectively tilt the reference pin 304 in opposite rotations within the guide pin hole 124. The guide pin hole 124 can be configured to have a smaller diameter at the forward end and a larger diameter at the rearward end. For example, as shown in FIG. 12A, the pin tilting mechanism 420 operates to tilt the reference pin 304 in a first rotation Rl (e.g., a rotation around an axis perpendicular to the guide pin hole axis A _G ) to settle the reference pin 304 within the guide pin hole 124. Further, as shown in FIG. 12B, the pin tilting mechanism 420 operates to tilt the reference pin 304 in a second rotation R2 opposite to the first rotation Rl so that the reference pin 304 settles within the guide pin hole 124. In some examples, the first and second rotations Rl and R2 are defined as pivoting along the X-axis and Y-axis. In other examples, the first and second rotations Rl and R2 are defined as pivoting along any axes perpendicular to the Z-axis.

[0082] The measuring device 204 operates to scan the reference plane 306 and the end face 120 when the reference pin 304 is tilted in the first rotation Rl and when the reference pin 304 is tilted in the second rotation R2. In some embodiments, if the two angles detected in the two positions are different, the angle values can be averaged to provide a single measurement.

[0083] The pin tilting mechanism 420 can be configured similarly to the pin shifting mechanism 400, such as employing one or more spring elements, a magnetic force, a motorized system, and/or gravity. In some examples, the functions of the pin tilt mechanism 420 is incorporated in the pin shifting mechanism 400 so that one mechanism performs both of the operations of the pin shifting mechanism 400 and the pin tilting mechanism 420.

[0084] Referring again to FIG. 5, a method of measuring of an angle of the end face 120 of the ferrule 100 is described for the purpose of measuring the angle of the guide pin hole axis AG relative to the end face 120. As the end face 120 is used as a reference for determining the angle of the guide pin hole 124, it is important to first determine an orientation or position of the end face 120 of the ferrule 100 to obtain accurate and reliable measurement of the angle of the guide pin hole 124 relative to the end face 120 of the ferrule 100. It is also important to consider a variety of external disturbances, such as a cable weight and movement, that influence calculation of the angle of the guide pin hole 124 relative to the end face 120 of the ferrule 100.

[0085] In some embodiments, the shoulder 1 18 of the ferrule 100 is used as a reference to polish the end face 120 of the ferrule 100 and measure the position (e.g., angle or orientation) of the end face 120. For example, the shoulder 118 can be manufactured with strict tolerances with respect to the guide pin hole axis AG (e.g., +/- 0.03 degree). The angle of the end face 120 (either after or before polishing) of the ferrule 100 can be measured relative to the shoulder 118, and, then, the angle of the guide pin hole axis AG is calculated relative to the end face 120 of the ferrule 100.

[0086] The angle of the end face 120 of the ferrule 100 relative to the shoulder 1 18 of the ferrule 100 is subjected to various factors, such as a tolerance of the shoulder 118, a tolerance of an interface between the ferrule mounting head 206 and the ferrule mounting adapter 210 (e.g., a mating surface 252 of the ferrule mounting head 206 and the first end 214 of the ferrule mounting adapter 210), and a geometry of the fastening device 220. Therefore, these factors can play a role on an overall measurement process of the angle of the guide pin hole 124 relative to the end face 120 of the ferrule 100.

[0087] Accordingly, before detecting the angle of the guide pin hole axis A _G relative to the end face 120, the angle of the end face 120 of the ferrule 100 is first determined relative to the shoulder 118 of the ferrule 1 10, considering the factors that can have effects on the measurement of the angle of the end face 120 (e.g., the tolerances of the shoulder 1 18, the tolerance of the interface between the ferrule mounting head 206 and the ferrule mounting adapter 210, the geometry of the fastening device 220, and the clamping force (F) for securing the ferrule 100 to the ferrule mounting adapter 210 and/or the ferrule mounting head 206).

[0088] By way of example, the axis A _G of the first guide pin hole 124A is measured by detecting the end face 120 of the ferrule 100 along with the reference plane 306 (including 306A, 306B, 332, and 352), using the measuring device 124. The position of the first guide pin hole 124A is also measured by referring to the reference marks 308. During this process, the factors that influence the measurement of the end face 120, as described above, are taken into consideration in order to reliably and accurately measure the first guide pin hole 124A relative to the end face 120. The same process and consideration of the factors can be repeated for the second guide pin hole 124B.

[0089] The various examples and teachings described above are provided by way of illustration only and should not be construed to limit the scope of the present disclosure. Those skilled in the art will readily recognize various modifications and changes that may be made without following the example examples and applications illustrated and described herein, and without departing from the true spirit and scope of the present disclosure.