Patent Publication Number: US-6220763-B1

Title: Optical fiber buildout system

Description:
FIELD OF THE INVENTION 
     The invention relates generally to a device for coupling optical fibers. More particularly, the invention relates to an optical fiber buildout system having a narrow footprint that permits a greater number of optical fiber connections per unit area. 
     BACKGROUND OF THE INVENTION 
     Often times it becomes necessary to arrange a plurality of optical fiber connectors in a connection panel to facilitate multifiber connections. Typically, devices for holding connectors are mounted in the panel, but the connectors themselves are not connected to incoming or outgoing fiber paths until needed to provide service. Commonly used devices which are used to accommodate interconnections are generally referred to as couplings. One type of coupling which is mounted in a connection panel is known as a buildout system. 
     Coupling components of buildout systems such as buildout bases and caps can be received in the connection panels to accommodate the optical fiber connectors to be installed at a fixture time. This permits the installer to connect a first connector, which terminates an incoming or outgoing fiber path, to a buildout base and await future connection of a second connector which terminates another outgoing or incoming fiber path. 
     One frequently used optical fiber connector is the ST® connector, ST being a registered trademark of the AT&amp;T Corporation. The ST connector is disclosed, for example, in U.S. Pat. No. 4,934,785, which was issued on Jun. 19, 1990, in the names of Mathis and Miller. Other popular optical fiber connectors include the SC connector and the FC connector. 
     One known buildout system capable of accommodating ST, SC, and FC connectors is disclosed in U.S. Pat. No. 5,274,729, which issued on Dec. 28, 1993, in the names of King et al. The King et al. system includes a plurality of buildout bases, identified in the patent as “blocks,” that are adapted for mounting to a panel through a plurality of openings provided therein. Further disclosed is a plurality of buildout caps, identified in the patent as “buildouts,” that are adapted to be removably attached to the buildout bases mounted to the connection panel. The bases are provided with front apertures that each form a keyway that is adapted to align and receive a cylindrical sleeve housing of the caps. Both the bases and caps are open-ended such that they can receive the optical fiber connectors to be coupled within the buildout. Inside the cylindrical barrel of each cap is an attenuator element which is used to attenuate the signal traveling from one fiber to the next. 
     Although the King et al. system described above functions adequately well, demand for increasing numbers of optical fiber connections has prompted the design of smaller optical fiber coupling systems that occupy less space. For instance, one recently developed optical fiber connector is the LC® connector, LC being a registered trademark of Lucent Technologies, Inc. This connector is disclosed, for example, in U.S. Pat. No. 5,481,634, which was issued on Jan. 2, 1996, in the names of Anderson et al. The design of the LC connector is advantageous because the connector has a smaller footprint than each of its predecessor connectors and therefore requires less panel space. 
     Although development of the LC connector has shown that optical fiber connectors can be successfully reduced in size, similar size reduction of buildout systems is more problematic. In particular, reducing the size of the buildout creates a number of difficulties that do not exist or that are not as significant in the larger buildout systems currently used with the ST, SC, and FC connectors. One problem is that buildout manufacture processes become much more difficult as the buildout components and the structural features of these components become smaller. For example, the molding of extremely small structural details can be difficult. 
     Another problem with buildout size reduction relates to buildout strength and durability. Again, if the size of the buildout is substantially decreased, the strength and durability of the buildout likewise decreases and the likelihood of buildout failure increases. For instance, the design of the cylindrical sleeve housing of the buildout cap must be such that it can flex sufficiently to permit insertion of the attenuator and attenuator retention means, but must not permanently deform to the point at which the attenuator element could dislodge or be damaged. Furthermore, despite its reduced size, the buildout must withstand a certain degree of side loading applied to the buildout caps via the fiber cables to protect the fragile optical fibers contained therein. 
     A further complication created by reduced size occurs in the buildout assembly process. Specifically, assembly of the buildout cap and the attenuation means can be difficult when the constituent components of the buildout system are small, especially when such assembly is conducted out in the field. Therefore, provision must be made for structural features that permit the technician to manipulate more easily the components of the system to avoid structural damage to the buildout and optical fibers and to prevent delays in servicing. 
     Accordingly, it can be appreciated that it would be desirable to have a buildout system that can accommodate ST, SC, and FC connectors as well as LC connectors, which has a relatively narrow footprint such that connection panel space may be optimized. Furthermore, it would be desirable to have such a buildout system that can be relatively easily manufactured and assembled. Moreover, it would be desirable to have such a buildout system which is adequately strong and durable. The present disclosure discloses one such buildout system. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a buildout system generally comprising a buildout base, a buildout cap, an attenuator element, and a ferrule sleeve. The base includes a pair of opposed lateral sides that typically extend beyond the top and bottom sides of the base to form upper and lower side flanges. Extending outwardly from the upper and lower side flanges are upper and lower panel flanges. Each of the panel flanges normally is provided with a central notch defined by opposed side surfaces. Protruding from the front side of the buildout base is a plurality of gussets. 
     The buildout cap comprises top and bottom sides that include elongated latch tabs that extend outwardly therefrom. Typically, each latch tab has an arcuate, relatively wide base portion that is adapted for receipt between the lateral flanges of the base, and a relatively narrow upper portion that is adapted for receipt by the central notches of the base panel flanges. Normally formed at the juncture of the lateral side with the top and bottom sides of the cap are recesses that are adapted to receive the gussets of the base. 
     The front side of the cap supports a sleeve housing which is adapted to contain a ferrule sleeve that is used to align the ferrules of two optical fiber connectors within the buildout. The sleeve housing extends both outwardly and inwardly from the front side of the cap and has a substantially cylindrical passage that extends from a first opening formed at the front end of the sleeve housing to a second opening formed at the rear end of the sleeve housing. The front and rear ends of the sleeve housing passage are provided with inner flanges. Normally the flange at the rear end of the sleeve housing is formed as a continuous inner flanges that retain the ferrule sleeve in place. Formed at the tip of the sleeve housing is a top notch which joins an attenuator element travel slot that extends through the front side of the cap. Positioned opposite the top notch is a bottom notch also formed at the tip of the sleeve housing. 
     The attenuator element is adapted for insertion into a ferrule sleeve which, as identified above, is adapted for insertion into the cap sleeve housing. The ferrule sleeve has a continuous longitudinal slot that coincides with the attenuator element travel slot of the cap when the sleeve is disposed within the cap sleeve housing. 
     When the cap is connected to the base, the base portions of the latch tabs of the cap are positioned closely between the lateral sides of the base, and the upper portions of the latch tabs are positioned closely between the side surfaces of the panel flange notches. This coupling arrangement increases the resistance of the buildout by increasing the longitudinal contact surface area between the cap and base. 
     The objects, features, and advantages of this invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings. It is intended that all such additional features and advantages be included therein with the scope of the present invention, as defined by the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention. In the drawings, like reference numerals designate corresponding parts throughout the several views. 
     FIG. 1 is an exploded perspective view of a buildout system constructed in accordance with the present invention shown along with a connection panel and a pair of optical fiber connectors. 
     FIG. 2 is a front perspective view of the buildout base of the buildout system shown in FIG.  1 . 
     FIG. 3 is a rear perspective view of the buildout base shown in FIG.  2 . 
     FIG. 4 is a cross-sectional front perspective view of the buildout base shown in FIGS. 2-3. 
     FIG. 5 is a front perspective view of the buildout cap of the buildout system shown in FIG.  1 . 
     FIG. 6 is a rear perspective view of the buildout cap shown in FIG.  5 . 
     FIG. 7 is a cross-sectional rear perspective view of the buildout cap shown in FIGS. 5-6. 
     FIG. 8 is a cross-sectional partial side perspective view of the buildout cap shown in FIGS. 5-7 illustrating the features of the sleeve housing. 
     FIG. 9 is a front view of the buildout cap shown in FIGS. 5-7. 
     FIG. 10 is a front view of the sleeve housing shown in FIG. 8 illustrating the partial flanges. 
     FIG. 11 is rear perspective view of the attenuator element shown in FIG.  1 . 
     FIG. 12 is a front view of the attenuator element of FIG.  10 . 
     FIG. 13 is a side view of an alternative attenuator element. 
     FIG. 14 is a front perspective view of the ferrule sleeve of the buildout system shown in FIG.  1 . 
     FIG. 15 is a cross-sectional partial side perspective view of the buildout cap illustrating the positioning of the attenuator element and ferrule sleeve within the sleeve housing. 
     FIG. 16 is a perspective view of the buildout system shown in FIG. 1 illustrating connection of the buildout cap to the buildout base. 
     FIG. 17 is a cross-sectional side view of the buildout base and cap shown in FIG.  16 . 
     FIG. 18 is a cross-sectional side view of the buildout system shown in FIG. 1 illustrating connection of the buildout base to the panel and the coupling of two optical fiber connectors within the buildout. 
     FIG. 19 is an exploded perspective view of a second embodiment of a buildout system constructed in accordance with the present invention shown along with a connection panel and a pair of optical fiber connectors. 
     FIG. 20 is a front perspective view of the buildout base of the buildout system shown in FIG.  19 . 
     FIG. 21 is a front perspective view of the buildout cap of the buildout system shown in FIG.  19 . 
    
    
     DETAILED DESCRIPTION 
     Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several views, FIG. 1 illustrates, in exploded view, a buildout system or buildout  10  constructed in accordance with the present invention. As indicated in this figure, the buildout system generally comprises a buildout base  12 , a buildout cap  14 , an attenuator element  16 , and a ferrule sleeve  18 . 
     As shown in FIG. 1, the buildout  10  is typically used in conjunction with a connection panel  20  and two optical fiber connectors  22 . The panel is provided with an elongated continuous slot  24  which is adapted to accommodate a plurality of buildouts such as the buildout  10  shown in FIG.  1 . For purposes of illustration, the connectors  22  shown in FIG. 1 are LC connectors of the type described in, for example, U.S. Pat. No. 5,481,634, which is hereby incorporated by reference into the present disclosure. It is to be understood, however, that usage of the present invention is not limited to facilitating LC connectors, but further includes facilitating of ST, SC, and FC connectors, as well as connectors not yet in existence. As identified in FIG. 1, each connector  22  comprises a generally rectilinear housing  26  having an opening  28 . Protruding from the opening is a ferrule  30  which contains an optical fiber (not visible). This optical fiber extends from the tip of the ferrule  30 , along the length of the connector  22 , and outwardly therefrom through an optical cable  34 . To permit attachment of the connector to other apparatus, the connector is provided with a latch tab  36  that extends upwardly from the housing  26 . 
     FIGS. 2-4 illustrate the buildout base  12  in detail. The base comprises a housing  38  that is preferably composed of a resilient polymeric material such as polyethermiide. The housing generally comprises a top side  40 , a bottom side  42 , a front side  44 , a rear side  46 , and a pair of opposed lateral sides  48 , each of which typically is unitarily constructed with the housing. As indicated in FIGS. 2 and 3, the lateral sides  48  typically extend beyond the top and bottom sides  40  and  42  to form upper and lower pairs of side flanges  50 . Extending outwardly from the upper and lower side flanges  50  are upper and lower panel flanges  54  and  56 , respectively. Each of these flanges is provided with a central notch  55  defined by opposed side surfaces  53 . These flanges  50  are normally unitarily formed with the side flanges and are adapted for engagement with a connection panel in which the base is to be installed. Usually, one of the panel flanges is longer than the other to provide a visual aid for proper installation of the base. In the embodiment shown in FIGS. 2-4, the upper panel flange  54  is longer or taller than lower panel flange  56 , indicating the top end of the base. Extending outwardly from the top and bottom sides and between each pair of side flanges  50  is a latch tab  58  (FIGS.  3 - 4 ). These latch tabs are substantially arcuate in shape and typically are unitarily formed with the housing  38 . 
     Extending through the housing  38  from the rear side  46  of the base and opening  57  to the front side  44  of the base is an internal passage  60 . As depicted most clearly in FIG. 4, this passage is formed by an upper wall  62 , a lower wall  64 , and opposed lateral walls  66 . Extending between the two lateral walls  66  is a beam  68  which forms part of the front side  44  of the base (FIG.  2 ). This beam partitions the passage  60  to form openings  59  and  61  and therefore a keyway adapted for receipt of the buildout cap. Extending backward from the beam  68  along the lateral walls  66  of the passage  60  to the rear side  46  of the base is a pair of interior rails  70 . As shown in FIG. 4, each of these rails forms the general outline of a pair of contiguous, dissimilarly sized rectangles. Provided in the lower wall  64  of the opening is a channel  72 . The channel extends from the rear side  46  of the base to a point approximately half-way along the length of the passage  60 . The rails  70 , the channel  72 , and a pair of corner portions  73  formed with the rear side  46  of the base together provide the shape of the opening  57  provided in the rear side (FIG.  3 ). 
     Protruding from the front of the buildout base are upper and lower pairs of gussets  74 . As shown in FIG. 4, the gussets extend inwardly from the panel flanges  54  and  56 , and forwardly from the side flanges  50 . Typically the gussets are unitarily formed with the housing and are defined by an oblique edge  78  and a horizontal edge  80  and therefore are substantially triangular in shape. As explained in greater detail below, the gussets, along with the side flanges, are adapted to support securely the buildout cap against side loads applied thereto with the optical cable. Further indicated in FIG. 4, the lateral sides  48  extend a small distance beyond the front side  44  and between the gussets  74  to form vertical flanges  82 . 
     FIGS. 5-7 illustrate the buildout cap  14 . The cap comprises a generally rectilinear housing  86  that is preferably composed of a polymeric material similar to that used to construct the base  12 . The housing generally comprises a top side  88 , a bottom side  90 , a front side  92 , a rear side  94 , and a pair of opposed lateral sides  96 , each of which typically is unitarily constructed with the housing. Extending outwardly from the top side  88  and the bottom side  90  are elongated latch tabs  98 . Each latch tab has an arcuate, relatively wide base portion  100  that typically is unitarily formed with the top side  88 , and a substantially straight, relatively narrow upper portion  102  that is adapted for receipt by the central notches  55  of the buildout base panel flanges  54  and  56 . Formed at the juncture of the lateral side  96  with the top and bottom sides  88  and  90  adjacent the front of the cap are recesses  103  that, as described below, are adapted to receive the gussets  74  of the base  12 . Formed at the juncture of the lateral sides  96  and the front side  92  are vertical recesses  105  that are adapted to receive the vertical flanges  82  of the base. 
     As shown in FIG. 6, the rear of the cap  14  has an arcuate notch  104  formed therein. Like the upper panel flange  54 , this arcuate notch provides a visual aid which indicates the correct orientation of the cap to the technician. Passing through the arcuate notch  104  and the remainder of the rear side  94  of the cap is an internal passage  106 . Access to the passage  106  is provided through an opening  108  provided in the rear side  94  of the cap. At the other end of the passage  106  is an upper slot  109  and a sleeve housing  110 , through which the passage can be reached. As shown in FIG. 7, the internal passage  106  is formed by an upper wall  112 , lower wall  114 , and opposed lateral walls  116 . Formed along the lateral walls is a pair of interior rails  118 . The rails  118  extend from the rear side  94  of the cap to a ledge  120  formed on the inside surface of the front side  92 . Similar to the interior rails of the buildout base  12 , each of the interior rails  118  of the cap forms the general outline of a pair of contiguous, dissimilarly sized rectangles. Further provided in the lateral walls  116  is a pair of lower notches  122 . As indicated in FIG. 7, the upper wall  112  includes an inclined surface  124  that intersects and inclines toward the rear side  94  of the cap. 
     As indicated in FIG. 7, the front wall  92  supports the sleeve housing  110 . Typically, the sleeve housing is unitary formed with the front side  92  and extends both outwardly beyond the cap and inwardly into the internal passage  106 . FIG. 8 is a cross-sectional cut-away view of the cap which illustrates the sleeve housing  110  and a portion of the front side  92 . As indicated in this figure, the sleeve housing  110  is formed as a substantially cylindrical tube having a substantially cylindrical passage  126  that extends therethrough from a first opening  128  provided at the front end  130  of the sleeve housing to a second opening  132  provided at the rear end  134  of the sleeve housing. The cylindrical passage  126  comprises a relatively large main section  136  and a relatively small front section  138 . Although the front section  138  has a diameter that is slightly smaller than that of the main section  136 , the distal portion of the main section  136  has a slight taper  137  formed adjacent the second opening  132  that has an average diameter substantially similar in magnitude to that of the front section  138 . 
     At the rear end  134  of the sleeve housing is a continuous inner flange  140 . This inner flange is defined by a relatively straight surface  142  that extends substantially radially inward from the walls of the main section  136  of the passage, and by an angled surface  144  that creates a chamfer at the second opening  132 . At the front end  130  of the sleeve housing is a pair of partial inner flanges  146 . Unlike the continuous inner flange  140  formed at the rear end of the sleeve housing, the partial inner flanges extend from a point approximately 55 degrees from the bottom center of the sleeve housing passage (indicated by 0) to a top notch  152  formed at the tip of the sleeve housing (FIGS.  9 - 10 ). The partial inner flanges  146  are defined by an inner  148  and an outer  150  angled surfaces. Like the angled surface of the second opening, the angled surface  150  of the first opening  130  forms a chamfer at the opening  128 . 
     As shown in FIG. 8, the top notch  152  joins an attenuator element travel slot  154 . The travel slot  154  is both longer and wider than the top notch  152  and, as shown in FIGS.  5  and  7 - 8 , extends through the front side  92  of the cap outwardly beyond the sleeve housing  110 , and ends at an end point  156  adjacent the continuous inner flange  140 . Positioned opposite the top notch  152  is a bottom notch  158  which is approximately the same width as the top notch. The sleeve housing is the subject of U.S. patent application Ser. No. 09/148,388, filed concurrently herewith. 
     Illustrated in FIGS. 11 and 12 is an attenuator element  16 . The attenuator element or attenuator, is typically constructed unitarily from an acrylic material and comprises an optical member  160 . As depicted in FIG. 11, the optical member is substantially thin and planar and typically is formed as a disk, although it will be appreciated that other shapes are possible. Normally, the optical member has a thickness in the range of approximately 0.0028 inches to 0.072 inches, depending on the amount of attenuation desired. For example, an optical member 0.0028 inches thick provides approximately 0.5 dB of attenuation while an optical member 0.072 inches thick provides approximately 20 dB of attenuation. Although FIG. 11 depicts the optical member as being relatively thin, it will be appreciated that attenuator element can be constructed with a thicker or thinner optical member depending upon the amount of attenuation needed. Accordingly, the disk can be relatively thick and substantially cylindrical in shape as shown in FIG. 13 with optical member  160 ′. 
     The optical member  160  is connected to a neck portion  162 . The neck portion  162  is relatively short in length, the length dimension of the neck being smaller than the height (diameter) dimension of the optical member. As shown in FIGS. 11 and 12, the neck portion connects the disk to a head portion  164 , the purpose of which being described below. The head portion has opposed, substantially parallel sides  165 . As indicated in FIGS. 11-12, the attenuator element typically is provided with a removable grip  166 . The grip typically comprises a substantially planar body portion  168  that is connected to a wedge portion  170 . The wedge portion connects the body portion  168  of the grip  166  to the head portion  164  of the attenuator element. As shown in FIG. 11, the wedge portion  170  narrows as it approaches the body portion and terminates at a breaking point  172 . Constructed in this manner, the attenuator element can be manipulated by the technician by grasping the grip between the technician&#39;s fingers. Once the attenuator element has been placed into an appropriate location, the grip can be removed from the attenuator element by simply bending the grip laterally toward the side of the attenuator element until the grip breaks off. 
     The attenuator element  16  is specifically adapted for insertion into a ferrule sleeve  18 . As shown in FIG. 14, the ferrule sleeve  18  is a substantially cylindrical tube having a substantially cylindrical passage  173  formed therein. A continuous longitudinal slot  174  extends from a first end  175  to a second end  177  of the sleeve. In that the ferrule sleeve must flex slightly during installation, it is normally constructed of a flexible but durable material. Presently preferred for this material is metal such as phosphor-bronze, although it will be appreciated that polymeric or ceramic materials could alternatively be used. The attenuator element is the subject of U.S. patent application Ser. No. 09/148,271 filed concurrently herewith. 
     The primary components of a buildout system according to the present invention having been described, the assembly of the buildout will now be described. First, the optical member  160  of the attenuator element  16  must be housed inside the sleeve housing  110  of the cap. To accomplish this, the optical member  160  is placed within the ferrule sleeve  18  with the grip  168  and is slid along the continuous longitudinal slot  174  of the ferrule sleeve to a to a medial portion of the sleeve (FIG.  15 ). The neck portion  162  of the attenuator is wide enough to suspend the optical member within the ferrule sleeve to prevent it from contacting the ferrule sleeve inside surfaces and support the attenuator element on the sleeve. 
     Once the attenuator element is disposed within the ferrule sleeve, the grip  168  can be broken off from the attenuator element by bending the grip laterally as described above. Since the cross-sectional area of the breaking point  172  of the grip is small, a clean break can be achieved. Moreover, because the grip is broken off, as opposed to being sawed or ground off, polymeric residue created by the separation is minimal thereby avoiding contamination of the optical member  160 . 
     After the grip has been removed from the attenuator element, the ferrule sleeve  18  can be inserted into position within the sleeve housing  110  as shown in FIG.  15 . For insertion of the ferrule sleeve, and the attenuator element disposed therein, into the sleeve housing, one end of the ferrule sleeve is first passed through the top notch  152  and attenuator travel slot  154 . Because the cap is made of a resilient polymeric material, the sleeve housing flexes or expands laterally like a clamshell to accommodate the ferrule sleeve. Insertion of the ferrule sleeve is completed by passing the remainder of the ferrule sleeve into the sleeve housing through the top notch  152  and travel slot  154  until the entire sleeve snaps into place within the sleeve housing. At the moment the ferrule sleeve snaps into place, and audible click can be heard by the technician to tell him or her that the sleeve is correctly positioned. This click sound is created by the sleeve housing snapping back into its original, unflexed orientation. 
     Notably, the insertion of the ferrule sleeve is facilitated by the notches and slots provided in the sleeve housing. In particular, the presence of the top notch  152  and the elongated travel slot  154  in combination with a relatively short bottom notch  158  has been found to provide the resilience needed to permit insertion of the ferrule sleeve, and the strength needed to avoid breakage of the sleeve housing during this insertion. Moreover, the configuration of the partial inner flanges  146  minimizes the shearing of polymeric material from the sleeve housing during installation of the ferrule sleeve. Specifically, the space between the partial inner flanges at the top portion of the sleeve housing allows the ferrule sleeve to pass into the sleeve housing without removing fragments of the sleeve housing. 
     As shown in FIG. 15, the ferrule sleeve  18  fits within the sleeve housing  110  with a first end adjacent the continuous inner flange  140  and a second end adjacent the partial inner flanges  146  such that longitudinal shifting of the ferrule sleeve within the sleeve housing is minimized. The outer diameter of the ferrule sleeve is such that the first end of the ferrule sleeve is compressed slightly by the distal taper  137  of the main section of the cylindrical passage  126 , and the second end of the ferrule sleeve is compressed slightly by the front section  138  of the cylindrical passage  126 . This arrangement holds the ferrule sleeve snugly in place within the sleeve housing but permits minor flexing of the medial portion of the ferrule sleeve to reduce axial misalignment of the connector ferrules and to avoid breakage of the optical fiber and ferrules when they are shifted. 
     When the attenuator is seated within the sleeve housing, its head portion  164  is positioned within the attenuator element travel slot  154 . The head portion is sized and shaped to permit the attenuator element to travel longitudinally along the travel slot  154  in response to contact from an optical connector ferrule. As described below, this feature permits proper alignment of the optical member  160  between the optical fiber connector ferrules being coupled and further prevents breakage of the attenuator element. 
     Once the attenuator element  16  and ferrule sleeve  18  have been positioned within the sleeve housing, the buildout cap  14  can be releasably connected directly to the buildout base  12  as depicted in FIGS. 16 and 17. Because the base and cap are asymmetrical about their medial horizontal planes, the cap will only fit into the base in the orientation shown in FIGS. 16 and 17. The increased height of the base upper panel flange  54  and the arcuate notch  104  of the cap serve as visual indicators to aid the technician in making the connection. In particular, the upper panel flange and the arcuate notch indicate the respective top ends of the base and cap. Even if these indicators are not heeded, however, incorrect connection is prevented due to the keyed configuration of the base. 
     When the cap is connected to the base, the base portions  100  of the latch tabs  98  of the cap are positioned closely between the side flanges  50  of the base and inwardly of the latch tabs  58  of the base. The upper portions  102  of the latch tabs matingly engage the central notches  55  provided in the panel flanges  54  and  56  of the base and are positioned closely between the side surfaces  53  of the notches. During insertion of the cap into the base, the cap latch tabs first flex and then snap into place. When correctly snapped into place, the close fitting arrangement described above increases the buildout&#39;s resistance to side loads by providing a large contact surface area in the longitudinal (transmission) direction between the base and cap. Specifically, when a side load is applied to the cap, the force of the load is distributed along this enlarged contact surface area, reducing the possibility of buildout failure or exaggerated flexure. 
     In addition to the strength provided by the combination of the cap latch tabs and base side and panel flanges, further strength is provided to the buildout through the combination of the base gussets  74  and the cap recesses  103 . As shown most clearly in FIG. 16, the gussets  74  fit within the recesses  103  of the cap to further increase the longitudinal contact surface area between the base and cap. Accordingly, the buildout is highly resistant to side loads. This resistance to side loads is the subject of U.S. patent application Ser. No. 09/148,390 filed concurrently herewith. 
     As illustrated in FIG. 17, the sleeve housing  110  of the cap passes through the lower opening  61  formed in the front side  44  of the base. Because both the cap sleeve housing  110  and the opening  61  are offset toward the bottom of the cap and base respectively, incorrect coupling of the cap and base is prevented. Accordingly, the base and cap are connected in a keyed fashion. 
     FIG. 18 depicts usage of the base and cap (with the sleeve  18  removed for clarity) to couple first and second optical fiber connectors  22  in a panel  20 . As indicated in this figure, the base  12  releasably connects to the panel with the upper and lower panel flanges  54  and  56  and the latch tabs  58  contacting the panel. Housed inside the base is a first connector  22 . This connector is provided with its own latch tab  36  that releasably engages the inside of the base. Similarly, a second connector  22  is releasably disposed within the cap. As shown in FIG. 18, the ferrule  30  of the connector is housed within the sleeve housing  110  of the cap  14 . When the cap is correctly positioned within the base, the ferrules  30  of both connectors are housed within the sleeve housing  110  of the cap. Accordingly, the sleeve normally disposed in the sleeve housing  110  aligns the two ferrules, and therefore the optical fibers, with each other. Due to the resilience of the ferrule sleeve housed within the sleeve housing, the ferrules can shift slightly from side to side without the ferrules or the optical fibers being damaged. 
     As further indicated by FIG. 18, the attenuator element  16  is positioned between the tips of the two ferrules  30 . To prevent breakage of the attenuator during insertion of the cap  14  into the base  12 , the attenuator element can be displaced in the longitudinal direction of the sleeve along the attenuator element travel slot  154  of the cap. Due to the relative shortness of the neck portion of the attenuator element, the center of the optical member is radially offset above the central axis of the ferrules. This positioning further reduces the risk of attenuator element breakage by reducing the moment applied to the attenuator element during cap insertion. 
     FIGS. 19-21 illustrate a second embodiment of a buildout system  200  constructed in accordance with the present invention. As shown in these figures, the buildout system  200  of the second embodiment is similar in construction to that of the first embodiment. Therefore, the disclosure regarding this second embodiment, which follows, is primarily reserved for features specific to the second embodiment alone. 
     The buildout system  200  of the second embodiment generally comprises a buildout base  202 , a buildout cap  204 , an attenuator element  16 , and a ferrule sleeve  18 . Like the buildout system  10  of the first embodiment, the buildout system  200  of the second embodiment is typically used in conjunction with a connection panel  20  and two optical fiber connectors  22 . Although the attenuator element  16  and the ferrule sleeve  18  are substantially identical to those used in the first embodiment, the base  202  and cap  204  differ from those of the first embodiment. As indicated in FIG. 20, the vertical flanges  206  of the buildout base  202  extend forwardly a greater distance than those found in the first embodiment. Specifically, these vertical flanges  206  extend from the front side  44  of the base to the tips of the gussets  74  and between the upper and lower gussets such that the vertical flanges  206  are substantially reclinear and plate-shaped. 
     To accommodate the relatively large vertical flanges  206  of the base, the cap  204  is provided with vertical recesses  208  that are also larger than those found in the first embodiment (FIG.  21 ). When the cap  204  is releasably connected to the base  202 , the vertical flanges  206  of the base are received by the vertical recesses  208  such that the lateral sides of the cap are positioned closely between the vertical flanges of the base. Because the vertical recesses receive the vertical flanges  206 , the vertical recesses  208  are substantially rectilinear and similar in size and shape to the vertical flanges. 
     The spatial relationship between the vertical flanges  206  and the vertical recesses  208  further increases the size of the contact surface area between the base and cap to further reduce the possibility of buildout failure or exaggerated flexure. It is believed that with the combination of the latch tab arrangement, the gusset/recess arrangement, and the vertical flange/recess arrangement, the buildout can prevent damage to the optical components contained therein even when subjected to side loads of up to 5 pounds applied to the fiber cable of an optical fiber connector in a direction perpendicular to the longitudinal axis of a connector disposed in the cap. 
     While preferred embodiments of the invention have been disclosed in detail in the foregoing description and drawings, it will be understood by those skilled in the art that variations and modifications thereof can be made without departing from the spirit and scope of the invention as set forth in the following claims.