Abstract:
A connector for making an optical and/or electrical connection underwater or in a wet or severe environment, comprising first and second connector parts which are axially interengageable to establish the optical or electrical connection, the first connector part having relatively movable portions for relative movement to allow the optical or electrical connection to be established when the first and second connector parts are interengaged, and having latching means to prevent such relative movement. The latching means is preferably releasable by engagement with the second connector part.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the priority of U.S. Provisional Patent Application No. 60/627,730 filed Nov. 12, 2004. 

   BACKGROUND OF THE INVENTION 
   This invention relates to a connector for making an optical and/or electrical connection underwater or in a wet or severe environment. 
   Optical fibres are frequently used for communication purposes, and it is often necessary to form an optical connection between the ends of such fibres. This generally involves bringing together two connector components each supporting a respective fibre and making end-to-end contact between the fibres. In the case of underwater connectors, it is known to provide the connector components with end sealing arrangements so that the optical fibre ends are protected from the outside environment when the components are in a disconnected state, the end sealing arrangements opening up during connection to allow passage of one of the optical fibre ends therethrough in order to establish the optical connection. 
   It is known from WO 02/39169 (the contents of which are hereby incorporated by reference) to provide an underwater optical connector, in which a first connector part has a probe and a second connector part has a chamber containing optical quality oil and closed by a spring biased shuttle piston. The probe of the first connector part is also housed in a chamber containing optical quality oil, this chamber being provided in a forwardly spring biased shuttle. When the connector parts are mated, the shuttle is pushed rearwardly by the front of a plug of the second connector part, so that the probe emerges from the sealed environment of the shuttle and passes into the sealed environment of the second connector part. In doing so, the probe pushes back the shuttle piston of the second connector part. Once the probe is in the oil filled chamber of the second connector part, and with continued interengagement of the connector parts, a front nose portion of the probe advances forwardly but a sleeve of the probe is prevented from further advancement. This allows an optical member to emerge laterally from the probe and establish an optical connection with an optical member in the second connector part. 
   In this known system, the shuttle of the first connector part is slidably carried in a housing. When the connector is in the disconnected state, the shuttle is recessed in the housing, which has a shield portion projecting forwardly of the shuttle. The shield portion then serves to protect the shuttle from being accidentally moved rearwardly and compromising its sealed integrity against the outside environment. However, this arrangement also means that the forwardly projecting shield portion of the housing has to receive axially the plug of the second connector part before the plug front face engages the shuttle front face and advancement of the probe into the second connector part can begin. In the fully mated condition, by the time the shuttle and plug internal components have connected to establish an optical connection, the front edge of the shield portion is a considerable axial distance from the front of the plug. This “overlap” of the shield portion and the plug is comprised of the axial length of the shield portion into which the plug engages initially in order to make face-to-face contact with the shuttle, plus a further length as the plug fully engages the housing of the first connector part to establish the optical connection. However, in some circumstances, there is a constraint on the amount of overlap which can be accommodated. 
   Similar arrangements, in which a shuttle is recessed in a housing which projects forwardly of the shuttle, are known from WO 86/02173 and WO 99/31540. 
   SUMMARY OF THE INVENTION 
   According to a first aspect of the invention, there is provided a connector for making an optical connection underwater or in a wet or severe environment, comprising first and second connector parts which are axially interengageable to establish the optical connection, the first connector part having relatively movable portions for relative movement to allow the optical connection to be established when the first and second connector parts are interengaged, and having releasable latching means to prevent such relative movement. 
   The latching arrangement means that the relatively movable portions of the first connector part can be latched together when the connector parts are not interengaged, thereby minimizing the risk of accidental movement which might compromise the integrity of the first connector part. Such accidental operation can be avoided without the use of a forwardly projecting shield, for example. 
   The optical connector may be particularly useful in the context of establishing optical communication to a tubing hanger of a well head assembly. For example, in the case of making a connection horizontally into a tubing hanger with one connector part supported horizontally in the tubing hanger wall, the amount of space available for the connector parts to overlap axially is limited by the radial thickness of the tubing hanger wall. The connector of the present invention may be used with the second connector part in the tubing hanger wall, and with the first connector part radially outwardly of the tubing hanger wall when disconnected. The movable portion of the first connector part, which has to move to allow the optical connection to be established, can be positioned to form the frontmost portion of the connector part, and if it is latched it will not be accidentally actuated due to its exposed position. The overall axial overlap of the connector parts when mated can be reduced as compared to the connector of WO 02/39169 without a risk of compromising sealing integrity. 
   The invention therefore also provides a well head assembly comprising a radially inner member having a fiber optic extending therein, a radially outer member, and a connector as disclosed herein, wherein the connector serves to establish optical communication with the fiber optic. The radially inner member may for example be a tubing hanger whilst the radially outer member may be a spool body. 
   Preferably the first connector part is supported in the radially outer member and the second connector part is supported in the radially inner member. 
   The optical connector of the present invention may be useful in other situations where the amount of space available for at least one of the connector parts is limited. It may for example be useful in a well head assembly where the connector makes a vertical connection into a tubing hanger, because a relatively short axial overlap of the connector parts in the tubing hanger upper wall when mated will help to create space for components below the connector. 
   In preferred arrangements, the optical connection is established in an environment protected by fluid media, such as gel or oil or the like. 
   The relatively movable portions of the first connector part may be laterally or rotationally relatively movable, but are preferably axially relatively movable. The relatively movable portions may comprise a shuttle and a support therefor (e.g. a housing), the shuttle being rearwardly movable relative to the support to establish the optical connection. Thus, the shuttle may be latched to the support when the first connector part is not engaged with the second connector part, so that it will not be accidentally rearwardly moved to compromise the integrity of components protected in its interior. At the point when the latching means is released, the shuttle becomes rearwardly movable. 
   In preferred arrangements, the shuttle contains a first optical member for connection with a second optical member contained in the second connector part. The arrangement may be such that during interengagement of the first and second connector parts the first optical member emerges from the shuttle to establish the optical connection with the second optical member. It will be appreciated that by latching the shuttle to its support it cannot be prematurely moved to allow the first optical member to emerge therefrom. 
   It will generally be desirable for the first and second connector parts to properly align during engagement. Preferably therefore the first and second connector parts have respective alignment portions at their front ends. In preferred arrangements, one of the connector parts, e.g. the first connector part, has a receptacle for receiving a front portion of the other connector part, e.g. the second connector part. There may be provided respect alignment components comprising an axial alignment key on one connector part and an axial alignment slot on the other connector part. The key or slot may be provided on the inside wall of the receptacle, with the other alignment component being provided on the outside wall of the front portion of the connector part to be received therein. 
   In the preferred embodiments, the shuttle of the first connector part provides the receptacle in which the front portion of the second connector part is received during connection. Thus, the receptacle is part of the shuttle. 
   The latching means is preferably arranged to release the relatively movable portions of the first connector part by lateral movement of the latching means. So, in the case of a shuttle relatively rearwardly movable on a support to establish the optical connection, the latching means may extend laterally between the shuttle and the support to latch them together. The lateral movement of the latching means to release the relatively movable portions is preferably radially inward movement. In the embodiments having a shuttle rearwardly movable relative to a support, the support may comprise a housing disposed radially outwardly of the shuttle. The housing may accommodate only a rear portion of the shuttle in the disconnected state of the connector, whereby the shuttle projects forwardly of the housing. The rear portion may be relatively short, for example less than half the overall length of the shuttle. 
   Latching may be effected by abutment of respective axially facing surfaces. The latching means may for example have a rearwardly facing surface abutting against a forwardly facing surface. In a preferred arrangement, the latching means is provided on the shuttle and has a rearwardly facing surface which engages with a forwardly facing surface of the support e.g. housing. 
   The latching means may be releasable by an actuator or the like which may be operated externally of the connector or remotely. Thus release can be effected at the point when the connector parts are to be interengaged. Preferably, the latching means is releasable by engagement with the second connector part. Thus release can be effected automatically during the interengagement process. The arrangement is preferably such that the second connector part urges the latching means axially in order to effect release of the relatively movable portions. 
   The latching means may have a latch release portion and a latching portion which co-operate to effect release of the relatively movable portions of the first connector part. Thus, the latch release portion may act on the latching portion to cause it to release the relatively movable portions. The latch release portion may be urged axially rearwardly, preferably by the second connector part, to cause the latching portion to effect release. This may be achieved for example by at least one of the latch release portion and the latching portion having a surface slanted relative to the axial direction. In this type of arrangement, axial movement can be used to effect lateral movement and hence release of the latching portion. In a preferred embodiment, the latching portion has a slanted surface. The latch release portion may have a front facing surface for engagement by the second connector part and, rearwardly thereof, a part which co-operates with the latching portion. The latch release portion is preferably resiliently forwardly biased. When it is urged rearwardly against the resilient bias it can effect release of the latching portion. 
   In the embodiment where the shuttle has a receptacle for receiving a front portion of the second connector part, the front portion is preferably arranged to engage the latching means during entry of the front portion into the receptacle, so as to release the latching means. The part of the latching means which is engaged by the front portion of the second connector part is preferably arranged towards the rear of the receptacle. In the preferred arrangement in which the latching means has a latch release portion and a latching portion, the latch release portion preferably extends into the receptacle so as to be engageable by the second connector part, for example to be urged axially rearwardly to cause the latching portion to release the relatively movable parts. 
   According to a second aspect of the invention, there is provided a connector for making an optical connection underwater or in a wet or severe environment, comprising first and second connector parts which are axially interengageable to establish the optical connection, the first connector part having a housing and a probe, the probe extending in a shuttle, and the shuttle being axially rearwardly movable relative to the housing and the probe, and the second connector part having a chamber containing fluid media for receiving the probe during interengagement of the connector parts, wherein during such interengagement the second connector part engages the shuttle and the probe advances forwardly relative to the shuttle and into the chamber of the second connector part to establish the optical connection, and wherein in the disconnected state of the connector the shuttle projects forwardly of the housing. 
   The extent to which the housing overlaps axially with the second connector part when the connector parts are interengaged is reduced (or eliminated) as compared to the known connectors where the shuttle is recessed in a housing which projects forwardly of the shuttle. The connector is therefore advantageous in situations where there is a limited amount of space available for axial overlap. 
   The shuttle preferably projects forwardly of the housing in the interengaged state of the connector. Thus, when the shuttle has moved rearwardly relative to the housing, it still projects forwardly therefrom. In such embodiments, because the housing has no axial overlap with the second connector part when the connector parts are interengaged, there is no need for any space to be provided around the second connector part to receive the housing. 
   In preferred embodiments, the shuttle has an alignment portion at its front end and the second connector part has an alignment portion at its front end, whereby during interengagement of the connector parts the respective alignment portions engage with each other and overlap axially. Alignment can thus be assisted by the shuttle, rather than by the housing of the shuttle. 
   As discussed above, the connector may be used as part of a well head assembly in which the first connector part is supported in a radially outer member e.g. a spool body and the second connector part is supported in a radially inner member e.g. a tubing hanger. The connector according to the second aspect of the invention is particularly useful in the context of such assemblies, where the available space in the radially inner member is limited. 
   In the embodiments where the shuttle and the second connector part have respective alignment portions at their front ends, it is preferred that when the connector parts are interengaged the alignment portion of the shuttle extends into the radially inner member to engage with the alignment portion of the second connector part. 
   Although latching of the shuttle relative to its housing in the case of the connector of the second aspect of the invention is preferred, it may not be necessary if for example the shuttle is biased to a forward position by a relatively stiff spring. 
   It will be appreciated that the various preferred features of the connector of the first aspect of the invention may also be preferred for the connector of the second aspect of the invention. 
   The optical connector of both aspects of the invention may be used purely to establish one or more optical connections, or it may also include electrical contacts for establishing one or more electrical connections. The optical and/or electrical contacts of the respective connector parts are preferably arranged to make their connections in an environment protected by fluid media such as gel or oil or the like. 
   The invention also extends to connectors for making an electrical connection underwater or in a wet or severe environment, i.e. without there being an optical connection. 
   Thus in a third aspect of the invention, there is provided a connector for making an electrical connection underwater or in a wet or severe environment, comprising first and second connector parts which are axially interengageable to establish the electrical connection, the first connector part having relatively movable portions for relative movement to allow the electrical connection to be established when the first and second connector parts are interengaged, and having releasable latching means to prevent such relative movement. 
   In a fourth aspect of the invention, there is provided a connector for making an electrical connection underwater or in a wet or severe environment, comprising first and second connector parts which are axially interengageable to establish the electrical connection, the first connector part having a housing and a probe, the probe extending in a shuttle and the shuttle being axially rearwardly movable relative to the housing and the probe, and the second connector part having a chamber containing fluid media for receiving the probe during interengagement of the connector parts, wherein during such interengagement the second connector part engages the shuttle and the probe advances forwardly relative to the shuttle and into the chamber of the second connector part to establish the electrical connection, and wherein in the disconnected state of the connector the shuttle projects forwardly of the housing. 
   The various preferred features of the first and second aspects discussed herein are applicable to the electrical connector of the third and fourth aspects, with references to establishing an optical connection being understood as references to establishing an electrical connection where appropriate. In preferred embodiments the probe of the first connector part comprises an electrical contact pin and a corresponding electrical contact socket is provided on the second connector part. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     A preferred embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: 
       FIG. 1  is a perspective view of a first connector part; 
       FIG. 2  is a front end view of the first connector part; 
       FIG. 3  is a longitudinal sectional view on the lines III—III in  FIG. 2 ; 
       FIG. 4  is a longitudinal sectional view on the lines IV—IV in  FIG. 2 ; 
       FIG. 5  (shown in two parts, as  FIGS. 5A and 5B ) is a longitudinal sectional view similar to that of  FIG. 3  but to an enlarged scale and showing also the internal components of the first connector part; 
       FIG. 6  is a perspective view of an optical pin contact showing its condition when the connector is fully mated; 
       FIG. 7  is a longitudinal sectional view of the optical pin contact of  FIG. 6 ; 
       FIG. 8  is a longitudinal sectional view of a second connector part showing its internal components; 
       FIG. 9  is a longitudinal sectional view showing the first and second connector parts prior to mating; 
       FIG. 10  shows a longitudinal sectional view of the first and second connector parts at an intermediate mating stage, when the latching means has been released; 
       FIG. 11  shows the first and second connector parts when fully mated; and 
       FIG. 12  shows a wellhead assembly in which the connector is installed. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1 to 5  show a first connector part  1  and  FIG. 8  shows a second connector part  2 . The first connector part  1  has a housing  4  in which a shuttle  6  is axially movably located, biased to a forward position by a shuttle spring  8 . The shuttle spring is seated against a rear wall  10  of the housing  4  and at its front it engages a collar  12  which abuts against a shoulder  14  of the housing. 
   The shuttle  6  has a cylindrical housing  16  which at its rear end  18  is fixed to the collar  12  and which has at its front end a forwardly projecting annular wall  46  forming a receptacle  20  for receiving a plug  22  of the second connector part  2  (see  FIG. 8 ). The wall portion  46  has formed therein an axially extending alignment slot  44 . 
   Latching means for latching the shuttle  6  to the housing  4  includes a latch release portion in the form of a latch release sleeve  24  and a latching portion in the form of a pair of latch arms  40 . The latch release sleeve  24  is fitted around the cylindrical housing  16 . The latch release sleeve  24  has a pair of diametrically opposed latch release arms  26 , received in respective longitudinal slots  27  in the cylindrical housing  16 . Each latch release arm has a front end portion provided with a forwardly facing surface  28  against which, during the mating procedure, a front face  30  of the plug  22  of the second connector part  2  engages (see  FIG. 8 ). At its rear, the latch release sleeve  24  has an annular rear end face  32  engaged by a latch spring  34  which is seated against the collar  12  and biases the latch release sleeve  24  forwardly. The annular end face  32  is interrupted by a pair of diametrically opposed rectangular cutout regions  36  which receive respective wedge portions  38  provided at the front ends of the pair of latch arms  40 . The wedge portions have rear faces  50  which engage a front face  52  of the housing  4  to latch the shuttle in its forward position. The wedge portions have forward faces  39  slanted with respect to the axial direction. The latch arms are arranged in diametrically opposed manner and are joined together at their rear ends by a ring portion  41 . 
   As seen in  FIG. 8 , the plug  22  of the second connector part  2  has a forwardly opening annular space  42  around its front part. The plug  22  has a radially outwardly protruding and axially extending alignment key  48  for rotationally aligning with the corresponding slot  44  at the front of cylindrical housing  16  of the shuttle  6  of the first connector part  1 . 
   The operation of the latching means will now be described. When the first connector part  1  is in the condition shown in  FIGS. 1 to 4  the shuttle  6  is latched in position and cannot be moved rearwardly relative to the housing  4 . When it is desired to mate the two connector parts, the plug  22  of the second connector part  2  moves into the receptacle  20  of the shuttle cylindrical housing  16 . The annular wall  46  of the receptacle  20  is received in the corresponding annular recess  42  in the second connector part  2 . The longitudinal forward facing alignment slot  44  formed in the annular wall  46  receives the alignment key  48  in the plug  22 , ensuring that the two connector parts are rotationally aligned. The forward faces  28  of the latch release arms  26  are engaged by the front face  30  of the second connector part  2  and pushed rearwardly. The rear facing edges of the cutout portions  36  in the latch release sleeve  24  engage the slanted surfaces  39  of the wedge portions  38  of the latch release arms and, with rearward movement of the latch release sleeve  24 , force the wedge portions radially inwardly until their rear faces  50  no longer engage the front face  52  of the housing  4 . This allows the shuttle housing  16  to move rearwardly against the bias of shuttle spring  8  upon further engagement of the connector parts  1  and  2 . 
   When the connector parts are to be disengaged, the shuttle cylindrical housing  16  returns to the position shown in  FIGS. 1 to 4  under the effect of shuttle spring  8 . As the plug  22  disengages from latch release arms  26  the latch release sleeve  24  returns to its forward position under the bias of latch spring  34  and thereby permits the wedge portions  38  of latch arms  40  to return to their radially outer positions under their own resilience. The rear faces  50  of the wedge portions  38  engage the front face  52  of housing  4  once again, thereby latching the shuttle  6  in its forward position. 
     FIGS. 5 ,  6  and  7  show the internal components of the first connector part  1 . An axially arranged probe  52  projects rearwardly from the rear support  10 . A pair of optical fibres  54  extend into the probe  52  via a sealed rear opening  11  and along a passage  56  in the probe to a pair of optical contacts  58  supported by a pair of rigid optical contact support tubes  60 . The forward parts of the optical fibres are shown in  FIGS. 6 and 7  in the position adopted when the connector parts are fully mated. At the front ends of the optical contacts  58 , respective optical pins  62  are provided. 
   At its forward end the probe  52  has a nose portion  66 . It will be possible in a modification for the rear part of this nose portion to have on its outer cylindrical surface one or more electrical contacts, which may be connected to one or more electrical conductors extending rearwardly of the probe to provide an electrical connection through to the rear of the first connector part. A suitable contact portion is shown as item  202  in WO 02/39169. However, in the embodiment shown and described, the connector is purely an optical connector and so it does not include electrical contacts. 
   To the rear of the nose portion  66  a sliding sleeve  68  is supported on a pair of axially extending arms  70 , to the front end of which the probe nose portion  66  is secured. At its rear end the sliding sleeve  68  has a rear shoulder  72  which is engaged by the front end of a probe spring  74 , the rear end of which is seated against a main body  76  of the probe  52 . The nose portion  66 , the support arms  70  and the main body  76  of the probe  52  are all fixed in position within the housing  4 , with the sliding sleeve  68  being rearwardly slidable with respect thereto. 
   The front parts of the optical support contact tubes  60 , in the unmated condition of the connector, engage a slanted passage  61  of the sliding sleeve  68 . The optical contacts  58  are thus supported at an angle to the axial direction. A pair of front openings  64  are provided at the forward ends of the slanted passages  61 , where a seal  63  is also provided. Each support tube  60  is provided with an outwardly directed lug  80  which engages in a respective transverse slot  82  formed in a respective support arm  70 . 
   Thus, the optical contacts  58  including the optical pins  62  are contained within the periphery of the probe  52  when viewed in the axial direction, when the connector parts are disconnected. The optical pins  62  remain inside the slanted passage  61  in the disconnected state. 
   In the case of the modification having a nose portion  66  with one or more electrical contacts, the support arms  70  may be electrically conductive, or may support one or more electrical conductors, to provide the electrical connection through to the rear of the first connector part. 
   The arrangement provided by the shuttle  6  for sealing and protecting the probe  52  from the outside environment will now be described with reference to  FIG. 5 . The shuttle  6  has a rear sleeve  84  to which the probe  52  is slidably sealed by a pair of O-ring seals  86 . Towards its front the rear sleeve  84  has a front lip  113 . The outside of the rear sleeve  84  is secured to the collar  12  which is forwardly biased by spring  8  within the housing  4 . The shuttle  6  defines a chamber  88  around the front of the probe  52 : a probe chamber. The probe chamber  88  is defined within a primary diaphragm  90  filled with optical quality fluid media. The primary diaphragm  90  has a front wall  92  defining an opening  94  which is sealingly engaged by the nose portion  66  of the probe  52 . The primary diaphragm has a generally cylindrical side wall  96  extending to a rear flange  98  captured between the outside of the shuttle rear sleeve  84  and a diaphragm retaining sleeve  100 . The diaphragm retaining sleeve  100  is itself supported between the shuttle rear sleeve  84  and the shuttle cylindrical housing  16 . The diaphragm retaining sleeve  100  is formed with radial ports  101 , communicating with an annular space  103  between the outside of sleeve  100  and the inside wall of the shuttle cylindrical housing  16 . The annular space  103  communicates with the outside via the longitudinal slots  27  in the housing  16  which accommodate the latch release arms  26 . Thus, the outside of primary diaphragm  90  is effectively exposed to outside pressures and so allows volume changes within probe chamber  88  to equalise the pressure therein with external pressure. This minimises any tendency for outside water or other contaminants to enter the probe chamber  88 . 
   The probe chamber  88  comprises an outer sub-chamber  102  and an inner sub-chamber  104 , both filled with fluid media. The inner sub-chamber  104  is defined by a secondary diaphragm  106  which is seated on the outside of shuttle rear sleeve  84 . The secondary diaphragm  106  has a front wall  108  formed with an opening  110  through which the probe nose portion  66  passes in slidable and sealing manner. The secondary diaphragm  106  has a generally cylindrical side wall  112  coaxial with the shuttle sleeve  84 , the sleeve being formed with radial ports  114  to communicate the side wall  112  with the interior of the sub-chamber  104 . The outside of secondary diaphragm side wall  112  is exposed to the pressure in the outer sub-chamber  102 , thereby enabling inner sub-chamber  104  to equalise its pressure relative to outer sub-chamber  102 . Outer sub-chamber  102  is able to equalise its pressure relative to the outside by exposure of primary diaphragm side wall  96  to outside pressure via the previously described radial ports. 
   The front opening  64  of optical fibre support tube  60  is located in the inner sub-chamber  104  when the connector parts are disconnected, as shown in  FIG. 5 . 
   The second connector part  2  will now be further described with reference to  FIG. 8 . The plug  22  is supported in a second connector outer housing  116  by a retaining ring  118  located generally axially centrally of the plug  22 . To the rear of the retaining ring, the outside of the plug is sealed to the inside of the outer housing by an O-ring  162 . The retaining ring  118  is formed with an external screw thread engaging with an internal screw thread formed on the housing  116 . An outer retaining ring  120  extends round the front part of the plug  22 , with the forwardly opening annular space  42  disposed radially outwardly of the plug and radially inwardly of the retaining ring  120 . The outside of retaining ring  120  is provided with a screw thread for screwing to a corresponding internal thread formed in a bore  122  in a wall  124  of a tubing hanger  126  (see  FIG. 9 ). The outer housing  116  is provided with an alignment key  128  projecting radially outwardly therefrom. The alignment key  128  aligns with an axial slot  130  in the bore  122  of the tubing hanger wall  124 . The outside of the outer housing  116  is provided with three O-seals  132  for sealing the housing to the bore  122 . A rearwardly facing conical face  134  is also provided on the outside of housing  116  to seal with a corresponding conical face  136  of the bore  122  when the retaining ring  120  is tightened. 
   A pair of optical fibres  136  extend upwardly along the tubing hanger wall in a protective tube  138 . The protective tube joins a penetrator  140  at the rear of outer housing  116  where the optical fibres  136  pass into the housing. At the front ends of the optical fibres there is provided a pair of optical contacts  142  each arranged at an angle to the axial direction. The optical contacts each include a spring  144  allowing rearward resilient movement of an optical ferrule within a ferrule holder  147  at the front of the optical contact  142 . This is a known optical contacting arrangement. 
   An outer chamber  146  containing fluid media is defined within a primary diaphragm  148  having a front wall  150  formed with an opening  152  in which a shuttle piston  154  is sealingly engaged. The primary diaphragm  148  has a circumferentially extending side wall  156  terminated at its rear with a flange  158  secured to the inside of a plug inner housing  160 . The inner housing  160  is sealed by an O-ring  162  to the inside of the outer housing  116 . The side wall  156  is surrounded by a retaining sleeve  164  formed with radial ports  166  and the inner housing  160  is formed with radial ports  168 . The outside of the side wall  156  of the primary diaphragm is thus communicated with the outside via radial ports  166  and  168  and annular space  42 . The communication of the outside of the primary diaphragm  148  with the outside environment allows the outer chamber  146  to change in volume in response to external pressure changes and displacements due to entry of the probe  52 . The pressure in the chamber may therefore be equalised with external pressure so as to minimise any opportunity for external water or contaminants to enter the chamber. 
   An inner chamber  170  is defined axially inwardly of the outer chamber  146  and is also filled with fluid media. The inner chamber  170  is defined within a secondary diaphragm  172 . The inner diaphragm has a front wall  174  formed with an opening  176  through which the shuttle piston  154  passes in sealing manner. The secondary diaphragm  172  has a circumferentially extending side wall  178 , of generally conical shape in order to accommodate the pair of optical contacts  142 . The outside of the side wall  178  is exposed to pressure in the outer chamber  146 , thereby allowing pressure equalisation of the inner chamber  170  relative to the outer chamber  146 . The secondary diaphragm  172  is supported at its front end on a sleeve  180  around the shuttle piston  154 . The sleeve  180  is formed with a slot opening  182  allowing the optical contacts  142  to be positioned in close proximity to the shuttle piston  154  and, as will be described later, to allow the optical contact pins  62  to gain access to the optical contacts  142 . At its rear the secondary diaphragm  172  is retained against the inner housing  160  and the outer housing  116  by a retaining ring  183 . 
   The shuttle piston  154  is forwardly biased by a shuttle piston spring  184 , so that in the unmated condition of the second connector part  2  shown in  FIG. 8  the shuttle piston blocks and closes opening  152 , which forms the entrance to the fluid filled outer chamber  146 , and the opening  176 , which forms the entrance to the fluid filled inner chamber  170  where the optical connections are to be established. The shuttle piston has at its rear a flange  186  which abuts against a shoulder  188  on the sleeve  180  to define its forward most position. 
   In the modification of the connector providing an electrical connection, an electrical contact socket may be provided on a radially inwardly facing surface of the sleeve  180 , to receive an electrical contact provided on the nose portion  66  of the probe  52  when the shuttle piston  154  is pushed back. A suitable contact socket is shown as item  130  in WO 02/39169. 
   In a further modification in which the connector is an electrical connector only, probe  52  may be formed as an electrical contact pin for engagement in an electrical contact socket provided radially outwardly of shuttle piston  154 , with no optical contacts being provided. 
     FIG. 12  shows a well head assembly  200  of the “horizontal tree” type in which the connector is installed. The well head assembly rests on the sea-floor  202  and comprises a spool body  204  from which a production line  206  emerges horizontally. The horizontal tree is capped by a tree cap  208 . Within the spool  204  body a tubing hanger  126  is supported. The downhole part of the oil production line is secured to the tubing hanger which serves to divert the production line from a vertical to a horizontal orientation. The tubing hanger  126  is connected via a dry mated connector  215  to a downhole instrument cable  212  which also passes from a vertical to a horizontal orientation inside the tubing hanger. The first connector part  1  for the instrument cable is supported in a horizontal bore th rough the spool body  204  and extends rearwardly therefrom into a bonnet assembly  214 . The second connector part  2  is supported in the tubing hanger wall. At the rear of the bonnet assembly  214  an actuator mechanism  216  is provided in order to actuate the first connector part  1  forwardly to effect mating of the connector and rearwardly to de-mate the connector. At the side of the bonnet assembly  214  there is a connection to an underwater cable or hose  213 . 
   Further details of the arrangement of the first and second connector parts on the horizontal tree well head assembly are shown in  FIG. 9 , with the connector parts de-mated. The first connector part  1  is supported in a casing  190  which is secured to the bonnet assembly  214  and projects forwardly therefrom into a horizontal bore in the spool body  204 . An actuator sleeve  192  is secured to the housing  4  of the connector  1  and is provided with a guide key  194  engaged in a guide slot  196  of the casing  190  for axial forward and rearward movement effected by the actuator mechanism  216 . The probe  52  of the first connector part is also fixed to move with the actuator mechanism  216 , so that the actuator sleeve  192 , the connector housing  4  and the probe  52  all move together with no relative axial movement. 
   The second connector part  2  is supported in the tubing hanger  126  in the manner previously described. 
     FIGS. 9 ,  10  and  11  respectively show the connector when de-mated, when the latch arms  40  have just been released, and when fully mated. The mating process will now be described. 
   In the de-mated condition shown in  FIG. 9 , the actuator sleeve  192 , the connector housing  4  and the probe  52  are in a rearward position. The actuator mechanism  216  is operated to move these components forwardly, guided by the guide key  194  in the guide slot  196 . The annular wall  46  of the shuttle cylindrical housing  16  engages in the annular space  42  of the second connector part  2 , with the alignment key  48  of the second connector part engaging in the alignment slot  44  of the first connector part. During this movement the shuttle  6  moves with the connector housing  4  with no relative axial movement, by virtue of the engagement of the latch arms  40  with the housing  4 . 
     FIG. 10  shows the stage when the annular wall  46  of the shuttle cylindrical housing  16  is fully advanced into annular space  42  of the second connector part  2 . As described previously, during the last part of the movement of annular wall  46  into annular space  42 , the front face  30  of the plug  22  engages the front surfaces  28  of the latch release arms  26  so as to urge the arms rearwardly and effect disengagement of the latch arms  40  from the connector housing  4 . The shuttle  6  is then free to move axially rearwardly relative to the housing  4 . At the stage shown in  FIG. 10 , when the latch arms  40  have just been released, the shuttle  6  is fully forward so that the nose portion  66  of the probe  52  continues to block the opening  94  in the primary diaphragm  90  of the first connector part  1  and also blocks the opening  10  in the secondary diaphragm  106 . The shuttle piston  154  of the second connector part  2  is in its forward most position, closing the opening  152  in the primary diaphragm  150  and also the opening  176  in the secondary diaphragm  178 . The front face of the nose portion  66  is engaged with the front face of the shuttle piston  154 . 
   With continued advancement of the actuator mechanism  216 , the probe  52  of the first connector part advances into the second connector part. The probe nose portion  66  pushes back the shuttle piston  154  and slidingly engages in the seal openings  152  and  176  to form respective seals therewith. At this point, the shoulder  72  of the sliding sleeve  68  of the probe  52  engages the front lip  113  of the shuttle rear sleeve  84  so that it can no longer move forwardly. The cylindrical front part of the sliding sleeve  68  therefore remains in the diaphragm openings  152  and  176  of the second connector part  2 , to maintain the seals to the respective chambers  146  and  170  of that connector part, whilst the rear part of the sliding sleeve  68  rests in the diaphragm openings  94  and  10  of the first connector part I to maintain the seals of the respective chambers  102  and  104  in that connector part. 
   As the probe  52  continues to advance forwardly, its nose portion  66  separates from the retained sliding sleeve  68  and advances forwardly into the inner chamber  170  of the second connector part  2 . During this process the spring  74  of the first connector part  1  compresses, as does the spring  184  of the second connector part  2  (as the shuttle piston  154  is pushed rearwardly). As the probe arms  70  advance forwardly, the optical contact support tubes  60  carried on those arms by lugs  80  sliding in grooves  82 , are urged laterally in sliding engagement with slanted passages  61  in sliding sleeve  68 . The optical contact support tubes  60  adopt the position shown in  FIGS. 6 and 7 , with the optical pins  62  projecting out of the probe at a slant to the axial direction. With further axial forward movement of the arms  70  the optical pins  62  engage in the ferrule holders  147  and thereby establish an optical connection. 
   The stroke length “L” through which the actuator sleeve  192 , the connector housing  4  and the probe  52  move forwardly to establish the optical connection is shown in  FIG. 9 , which also shows the distance “S” by which the shuttle  6  advances. The axial “overlap” of the first and second connector parts  1  and  2  when fully mated corresponds to the distance “S”, which is relatively short whilst enabling a reliable connection to be established. 
   To de-mate the connector, actuator mechanism  216  is operated to move the actuator sleeve  192 , the connector housing  4  and the probe  52  rearwardly. The de-mating sequence is then the reverse of the mating sequence.