Abstract:
Improved helmet mounting devices for an optical device are provided. The mounting devices herein include dual pivot axes providing multiple flip options for pivoting the viewing device and/or mount up and away from the user&#39;s line of sight. The dual pivot axes and multiple flip positions also allow the unit to be adapted for a variety of viewing devices.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority under 35 U.S.C.§119(e) based on U.S. provisional application Ser. No. 61/168,789 filed Apr. 13, 2009, which is incorporated herein by reference in its entirety. 
    
    
     INCORPORATION BY REFERENCE 
     Each of the aforementioned U.S. patents and patent applications is incorporated herein by reference in its entirety: Ser. No. 12/259,010 filed Oct. 27, 2008; Ser. No. 60/982,533 filed Oct. 27, 2007; Ser. No. 12/117,704 filed May 8, 2008; Ser. No. 60/928,239 filed May 8, 2007; Ser. No. 11/804,813 filed May 21, 2007; Ser. No. 10/959,906 filed Oct. 6, 2004; U.S. Pat. No. 7,219,370 issued May 22, 2007; and Ser. No. 60/509,136 filed Oct. 6, 2003. 
     BACKGROUND 
     The present disclosure relates to an improved system for mounting an optical device to headgear such as a field helmet, and specifically, a mount with dual pivot axis for providing multiple flip options for flipping an attached optical device to a flipped or stowed position out of the user&#39;s line of sight when the optical device is not in use. The optical device may be, without limitation, a night vision device enabling viewing under nighttime or other low light conditions, such as night vision goggles (NVG) or electronic night vision goggles (eNVG), night vision binoculars, night vision monocular devices, etc. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may take form in various components and arrangements of components, and in various steps and arrangements of steps. The drawings are only for purposes of illustrating preferred embodiments and are not to be construed as limiting the invention. 
         FIG. 1  is an isometric view taken generally from the front and side of an associated helmet carrying an associated optical device using a helmet mount system according to a first exemplary embodiment, wherein the optical device is positioned in front of the eyes of the user. 
         FIG. 2  is an isometric view of the embodiment appearing in  FIG. 1 , wherein the optical device is pivoted about a first mount pivot axis to a first stowed position. 
         FIG. 3  is an isometric view of the embodiment appearing in  FIG. 1 , wherein the optical device is pivoted about first and second pivot axes to a second stowed position. 
         FIG. 4  is an isometric view of the embodiment appearing in  FIG. 1 , showing the optical device removed and the helmet mounting system in a stowed position on the helmet. 
         FIG. 5  is an enlarged isometric view of the helmet mount system of  FIG. 1  in the deployed position with the optical device removed, wherein the optical device mounting shoe is positioned at a distal position away with respect to the user&#39;s eyes. 
         FIGS. 6 and 7  are enlarged views of the helmet mount system of  FIG. 5 , wherein the optical device mounting shoe is positioned at a proximal position with respect to the user&#39;s eyes. 
         FIG. 8  is an isometric view illustrating the manner of attaching and removing the optical device. 
         FIG. 9  is an exploded isometric view of the helmet mounting assembly appearing in  FIG. 5 . 
         FIG. 10  is an isometric view of a second embodiment helmet mounting system. 
         FIG. 11  is an enlarged view of the mount appearing in  FIG. 10 . 
         FIG. 12  illustrates the mount appearing in  FIG. 10  in a stored position. 
         FIG. 13  illustrates the mount appearing in  FIG. 10  with the optical device in a flipped up position. 
         FIG. 14  is an exploded view of the mount appearing in  FIG. 10 . 
         FIG. 15  is an exploded view illustrating the release and breakaway mechanisms. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawing  FIGS. 1-9 , wherein like reference numerals refer to like or analogous components throughout the several views, there appears an exemplary helmet mounting system embodiment  100 , which includes a bracket  104  attached to the front portion of a helmet  108 . The exemplary bracket  104  is secured to the front of the helmet  108 , e.g., via a plurality of threaded fasteners  109 . It will be recognized that the illustrated mounting bracket is exemplary only and other mounting brackets may be employed as well, including the flush-mount, bayonet mounting bracket as described in the aforementioned U.S. provisional application Ser. No. 60/928,239 filed May 8, 2007, or the strap mounted bracket or the track mounted bracket shown in the aforementioned U.S. Pat. No. 7,219,370. 
     A breakaway base  112  is secured to the mounting bracket  104 . The breakaway base  112  includes a sliding plate  114  which slides vertically with respect to an interface plate  110  engaging the bracket  104 , e.g., via threaded fasteners  111 . Alternatively, a removable attachment mechanism may be employed, such as a bayonet-type mount, for example, a bayonet mount in which a male bayonet mount member on the breakaway base engages a complimentary bayonet plate on the bracket  104  as described in the aforementioned U.S. application Ser. No. 12/259,010. 
     A depressible button  118  allows the sliding plate  114  to slide with respect to the interface plate  110  to provide a vertical adjustment of an attached optical device relative to the eye of the user. Preferably, the vertical adjustment mechanism is of the gear rack/gear tooth type described in the aforementioned U.S. Pat. No. 7,219,370. 
     A tri-fold pivot arm assembly  116  may be secured to the breakaway base  112  in breakaway fashion. The breakaway mechanism may be a selectable breakaway/non-breakaway mechanism as described in the aforementioned commonly owned U.S. Pat. No. 7,219,370, incorporated herein by reference and as described in greater detail below. 
     The pivot arm assembly  116  includes a first pivoting segment  120  secured to the sliding plate  114 , and a second pivoting segment  122 . The second pivoting segment  122  pivots relative to the first pivoting segment  120  about a first pivot axis  124 . A third pivoting segment  126  is pivotally attached to the second pivoting segment  122 . The third pivoting segment  126  pivots with respect to the second pivoting segment  122  about a second pivot axis  128 . 
     The second pivoting segment  122  is selectively pivotable with respect to the second pivoting segment  122  between a lower, operative or deployed position (see  FIG. 1 ), an intermediate position (see  FIG. 3 ) and a fully pivoted up position (see  FIG. 4 ). Likewise, the third pivoting segment  126  is selectively pivotable with respect to the second pivoting segment  122  between an operative or deployed position (see  FIG. 1 ), an intermediate position (see  FIG. 3 ) and a fully pivoted position (see  FIG. 2 ). 
     As best seen in  FIG. 1 , an attached optical device  130  is positioned in the deployed, viewable position when the second pivoting segment  122  is pivoted to the full down position and the third pivoting segment  126  is likewise pivoted to the full down position, that is, so that the third segment  126  is folded back along the second segment  122 . 
     As best seen in  FIG. 2 , when the attached optical device  130  is not in use, the device  130  may be moved to a first stowed position by leaving the second pivoting segment  122  in the full down position and pivoting the third pivoting segment  126  to the full up position, thereby elevating the optical device  130  above the line of sight of the user. In this manner, the optical device  130  may be selectively moved between the viewing position and a stowed position with a single action. 
     An alternative stowed position for the device  130  is seen in  FIG. 3 , wherein the second pivoting segment  122  is pivoted to the intermediate pivoted position and the third pivoting segment  126  is likewise pivoted to the intermediate position. Although moving the optical device  130  from the viewing position to this alternative stowed position requires two pivoting actions, it has the advantage of moving the device back farther toward the user and over the helmet when the optical device  130  is not in use, thus reducing neck strain. Thus, the alternative stowed position as shown in  FIG. 3  is advantageous when the optical device is not in use for relatively long periods of time. 
     The optical device  130  may advantageously be a low profile night vision device such as the AN/PVS-21 low-profile night vision goggle (LPNVG) available from Sensor Technology Systems, Inc., of Beavercreek, Ohio. It will be recognized, however, that the present invention may be adapted for use with all manner of night vision or other optical devices. By providing three pivoting segments, the present mounting system may readily be tailored for use with other viewing devices, including those with widely varying profiles or dimensions. 
     As best seen in  FIG. 4 , the mounting system  100  may also be pivoted to yet another stowed position, wherein the second pivoting segment  122  is pivoted to the fully upward pivoted position and the third pivoting segment  126  is pivoted to the full downward position. The stowed position appearing in  FIG. 4  provides compact storage of the mounting system  100  when the optical device  130  is not attached to the mount  100 . 
     In the illustrated exemplary embodiment, the breakaway mechanism includes a breakaway lever  127 , which is pivotable between a first, breakaway position and a second, non-breakaway position. When the breakaway lever  127  is in the breakaway position, the engagement between the breakaway base and the pivot arm  120  is removably detachable. That is, the pivot arm  120  will detach from the breakaway base upon the application of a predetermined force. When the lever  127  is moved to the non-breakaway position, the pivot arm  120  is rigidly attached to the breakaway base  112 . The breakaway mechanism may be as described in the aforementioned U.S. Pat. No. 7,219,370. 
     In an exemplary embodiment, when the breakaway lever  127  is in the first, breakaway position, protrusions  131  (e.g., which may be ball bearings) captured within and extending through openings in a breakaway housing  133  on the breakaway base  112  are resiliently urged into aligned and complimentary openings or depressions  135  on the first pivoting segment  120 . The resilient urging of the members  133  is caused by spring members (not shown) within the housing  133  and allows the pivot segment  120  to become detached from the breakaway base  112  upon the application of a predetermined force. When the lever  127  is moved to the nonbreakaway position, a cam surface (not shown) on the lever  127  compresses the internal spring members to compress and stack the spring coils and maintain the members  133  nonresiliently in the openings  135 . 
     In addition to the safety benefit of having a breakaway connection between the first segment  120  and the breakaway base  112 , the breakaway connection also provides a quick connect/disconnect mechanism for removing the optical device  130  from the helmet  108 . It will be recognized, however, that in alternative embodiments (not shown), the breakaway mechanism may be omitted. For example, in certain embodiments, the sliding plate member  114  may be adapted to provide a hinged or pivotal connection to the second pivoting segment  122  and the interface plate  110  may be adapted for a direct connection to the helmet or an interface member on the helmet, preferably via a bayonet-type connection as described above or other quick connect/disconnect mechanism. 
     In the illustrated preferred embodiment, a tilt adjustment mechanism for adjusting the tilt angle of the optical device to a desired line of sight or optical axis is not included, since a tilt adjustment is included on the AN/PVS-21 LPNVG. However, a tilt angle adjustment knob (not shown) may optionally be provided to allow the tilt angle of the optical device  130  to be adjusted to a desired line of sight or optical axis where the unit  100  is intended to be used with an optical device that lacks an integrated tilt angle adjustment. The optional tilt angle adjustment mechanism may comprise, for example, a threaded knob rotatably engaging a threaded shaft running in an elongate or arcuate slot which may be selectively loosened for adjustment and then tightened when the tilt angle is at a desired position. If desired, the optional tilt angle adjustment mechanism may be as described in the aforementioned U.S. application Ser. No. 12/259,010 or U.S. Pat. No. 7,219,370. 
     The first pivot segment  120  includes a hinge portion  137  including openings  139 . The second pivot segment  122  includes a proximal hinge portion  141  having openings  143  and a distal hinge portion  145  having openings  147 . The third pivot segment  126  includes a hinge portion  149  having openings  151 . 
     A first hinge or pivot pin  153  includes a button  155  secured to a first end thereof, e.g., via a threaded fastener  157 . A spring pin  159  is received within an opening  161  in the pivot pin  153 . The first hinge pin  153  lies along the first pivot axis  124 . 
     A second hinge or pivot pin  163  includes a button  165  secured to a first end thereof, e.g., via a threaded fastener  167 . A spring pin  169  is received within an opening  171  in the pivot pin  163 . The second hinge pin  163  lies along the second pivot axis  128 . In the depicted illustrated embodiment, the buttons  155  and  165  are on the same transverse side of the unit  100 . However, in alternative embodiments, the buttons  155  and  165  may be positioned on opposite transverse sides of the unit as shown in the alternative embodiment  300 , described below, so as to prevent inadvertent actuation of the button  155  or  165  when actuation of the other is intended. 
     The first hinge pin  153  extends through the aligned openings  139  and  143  of the respective hinge portions  137  and  141  of the first and second pivoting segments  120  and  122 , respectively, thereby providing a hinged or pivoting connection therebetween. 
     The second hinge pin  163  extends through the aligned openings  147  and  151  of the respective hinge portions  145  and  149  of the second and third pivoting segments  122  and  126 , respectively, thereby providing a hinged or pivoting connection therebetween. 
     A first spring  173  is received within a cavity  177  in the proximal hinge portion  141  and is coaxially received about the first hinge pin  153 . A second spring  175  is received within a cavity  179  in the distal hinge portion  139  and is coaxially received about the second hinge pin  163 . 
     A first retention disk  181  is secured to the opposite end of the first hinge pin  153  via a threaded fastener  183 . Locating pins  185  are rigidly received in the respective openings  187  in the disk  181 . Likewise, a second retention disk  191  is secured to the opposite end of the second hinge pin  163  via a threaded fastener  193 . Locating pins  195  are rigidly received in the respective openings  197  in the disk  191 . 
     The locating pins  185  are slidably received through openings  201  in the hinge portion  139  and slidably extend into a selected pair of complimentary openings (not shown) in the hinge portion  141 . The hinge portion  141  includes three pairs of openings (not shown) angularly displaced about the axis  124 , each of which corresponds to a selected angular position of the second segment  122  relative to the first segment  120 . In operation, to pivot the second pivoting segment  122  relative to the first pivoting segment  120 , the button  155  is manually depressed causing the pivot pin  153  to slide in the axial direction. The spring pin  159  engages the spring  173  and compresses the spring  173  when the button  155  is depressed. 
     As the hinge pin  153  is translated in the transverse direction along the axis  124 , the locating pins  185  are disengaged from the openings (not shown) in the hinge portion  141 , thereby allowing the second portion  122  to pivot freely with respect to the first portion  120 . After the second portion  122  is pivoted to a desired position relative to the first portion  120  and the locating pins  185  are brought into alignment with another set of locating openings (not shown) on the hinge portion  141 . The bias of the spring  173  urges the hinge pin  153  back to its original position, causing the locating pins  185  to slidingly engage the currently aligned set of openings (not shown) in the hinge portion  141 , thereby maintaining the first and second pivoting segments  120  and  122  in a fixed relative angular orientation. 
     Similarly, the locating pins  195  are slidably received through openings  211  in the hinge portion  149  and slidably extend into a selected pair of complimentary openings (not shown) in the hinge portion  145 . The hinge portion  145  includes three pairs of openings (not shown), angularly displaced about the axis  128 , each of which corresponds to a selected angular position of the second segment  122  relative to the third segment  126 . In operation, to pivot the third pivoting segment  126  relative to the second pivoting segment  122 , the button  165  is manually depressed causing the pivot pin  163  to slide in the axial direction. The spring pin  169  engages the spring  175  and compresses the spring  175  when the button  165  is depressed. 
     As the hinge pin  163  is translated in the transverse direction along the axis  128 , the locating pins  195  are disengaged from the openings (not shown) in the hinge portion  145 , thereby allowing the third portion  126  to pivot freely with respect to the second portion  122 . After the third portion  126  is pivoted to a desired position relative to the second portion  122  and the locating pins  195  are brought into alignment with another set of locating openings (not shown) on the hinge portion  145 . The bias of the spring  175  urges the hinge pin  163  back to its original position, causing the locating pins  195  to slidingly engage the currently aligned set of openings (not shown) in the hinge portion  145 , thereby maintaining the second and third pivoting segments  122  and  126  in a fixed relative angular orientation. 
     A carriage assembly  136  includes a sliding body  140  having rails  142  slidably received within grooves  144  formed in third pivoting segment  126 . Sliding movement of the sliding body  140  within the channels  144  provides a fore and aft adjustment mechanism for positioning the optical device at a desired distance from the user&#39;s eye.  FIG. 5  shows the carriage assembly at a position furthest from the user&#39;s eye.  FIG. 6  shows the carriage assembly at a position closest to the user&#39;s eye. In the depicted preferred embodiment, the fore and aft positioning is infinitely slidably adjustable therealong. A cam lever  148  is rotatably secured to the sliding body  140  and is rotatable about a pivot pin  152 . The cam lever includes a cam peripheral surface  156  which exerts a force against the sidewall of the third pivoting segment  126  to secure the sliding body at a desired position along the third segment  126  when the cam lever is in the locked position. When the cam lever is in the unlocked position, the sliding body  140  slides freely along the third segment  126 . 
     The carriage assembly also includes an optical device mounting shoe assembly  230 , which includes a mounting shoe  240 . The mounting shoe  240  is attached to the sliding body  140  via threaded fasteners  242 . The mounting shoe  240  includes a dovetail or like receptacle  244  for removably receiving a complimentary mating mounting foot member  247  of the optical device  130 . A retention member  246  is received within an opening  245  in the mounting shoe  240 . 
     The retention member includes a forward end  248  and a rearward end  250 . A pivot pin  252  is received within channels or grooves  254  on the mounting shoe  240  and extends transversely across the aperture  245  in the mounting shoe  240 . The retention member  246  includes a groove  256  receiving the pin  252  to pivotally secure the retention member in the opening  245 . 
     A spring  258  includes a first end received within an opening  268  in the rearward end  250  of the retention member  246 . A second end of the spring  258  bears against the sliding body  140 . In operation, the spring  258  urges the rearward end  250  into a complimentary depression or opening  259  on the mounting foot portion  247  of the optical device  130 . A release button  260  is slidably received between the mounting shoe  240  and the sliding body  140 . A pair of springs  262  urges the button  260  to the locked position. 
     In operation, to remove the optical device  130  from the mounting shoe, the button  260  is manually pressed inwardly. A ramped or inclined surface  264  on the button  260  slidingly engages the forward surface  248  of the retention member  246 , urging it downward as the button  260  is depressed inward. As the retention member pivots about the pin  252 , the rearward end  250  moves upward against the bias of the spring  258 , thereby disengaging the complimentary receptacle  249  on the optical device  130 , allowing the optical unit  130  to be removed. 
     Referring now to  FIGS. 10-15 , wherein like reference numerals refer to like or analogous components throughout the several views, there appears an exemplary helmet mounting system embodiment  300 , which includes a bracket  304  attached to the front portion of a helmet  108 . The exemplary bracket  304  is secured to the front of the helmet  108 , e.g., via a plurality of threaded fasteners  309 . It will be recognized that the illustrated mounting bracket is exemplary only and other mounting brackets may be employed as well, including the flush-mount, bayonet mounting bracket as described in the aforementioned U.S. provisional application Ser. No. 60/928,239 filed May 8, 2007, or the strap mounted bracket or the track mounted bracket shown in the aforementioned U.S. Pat. No. 7,219,370. 
     A breakaway base  312  is secured to the mounting bracket  304 . The breakaway base  312  includes a sliding plate  314  which slides vertically with respect to an interface plate  310  engaging the breakaway base  312 , e.g., via threaded fasteners  311 . 
     A pivoting lever  318  allows the sliding plate  314  to slide with respect to the interface plate  310  to provide a vertical adjustment of an attached optical device relative to the eye of the user. The lever  318  rotates between a locked position, wherein the sliding plate  314  is fixed relative to the interface plate  310 , and an unlocked position, wherein the sliding plate  314  is free to travel up and down vertically relative to the interface plate  310 . The lever  318  is connected to a lock  402  having a T-shaped cross-sectional shape via a threaded fastener  404 . The lock  402  engages and disengages from a track  406  via of the lever  318 . A wave spring  408 , preferably a heavy-duty wave spring, is located under the lever  318 , which applies enough pressure to keep the sliding plate  314  locked in a fixed vertical position when the lever is in the locked position. The T shaped lock has ramps on the leading edges so that when the lever  318  is rotated, the ramps engage the T track  406  first and compress the wave spring  408  as the lever is rotated to the locked position. 
     As best seen in  FIG. 15 , a mount assembly  300  may be secured to the bracket  304  in breakaway fashion. The breakaway feature works by pressing the breakaway button  327  to the right (relative to the user) when the mount is installed on the helmet and the serrated release button  410  is pushed all the way to the right. The breakaway button includes an elongate, transverse opening  411  receiving pins  413 . The opening  411  includes a stepped profile  415  engaging a notch  417  in a locking tongue member  412 . 
     By pushing the breakaway button  327  to the right, the stepped profile  415  raises the locking tongue  412  to a “half way” point and holds it there against the urging of a biasing spring  419 . By holding it at the half way point, the locking tongue  412  is now positioned so that a small inclined or ramped surface  414  is engaged on the locking surface of the bracket  304  (not shown) instead of the flat surface portion  416  of the locking tongue  412  as is the case when the breakaway button  327  is moved to the left. With the ramp  414  engaged on the mating surface of the bracket, the mount can be broken away from the helmet by an impact or application of force in the generally upward direction. 
     The release buttons  410  are adjoined by a slider  431  engaging a slot  441  in the tongue  412 . The slider  431  having first and second elongate openings  433  and an angled elongate slot  435 . Pins  437  affixed to the base  312  run in the respective slots  433 . Pin  439  in the tongue  412  runs in the angled slot  435  to selectively raise and lower the tongue  412  when the slider  431  is moved side to side. To remove the mount  300  from the helmet  108 , the slider is moved to the left, which moves the tongue  412  upward to disengage the tongue  412  from the complimentary depression or receptacle (not shown) on the bracket  304 . 
     The pivot arm assembly includes the sliding plate  314 , which defines the first pivoting segment, and which is pivotally attached to a second pivoting segment  326 . The second pivoting segment  322  pivots relative to the first pivoting segment  314  about a first pivot axis  324 . A third pivoting segment  326  is pivotally attached to the second pivoting segment  322 . The third pivoting segment  326  pivots with respect to the second pivoting segment  322  about a second pivot axis  328 . 
     The second pivoting segment  322  is selectively pivotable with respect to the first pivoting segment  314  between a lower, operative or deployed position (see  FIG. 10 ) and a fully pivoted up or stored position (see  FIG. 12 ). Likewise, the third pivoting segment  326  is selectively pivotable with respect to the second pivoting segment  322  between an operative or deployed position (see  FIG. 10 ), a flipped-up position (see  FIG. 13 ). 
     As best seen in  FIG. 10 , an attached optical device  130  is positioned in the deployed, viewable position when the second pivoting segment  322  is pivoted to the down position and the third pivoting segment  326  is likewise pivoted to the down position, that is, so that the third segment  326  is folded back along the second segment  322 . 
     As best seen in  FIG. 12 , when the attached optical device  130  is not in use, the device  130  may be moved to a stowed position, wherein the second pivoting segment  322  is pivoted to the upper pivoted position and the third pivoting segment  326  is in the deployed, folded back position. The stowed position appearing in  FIG. 12  provides compact storage of the mounting system  300  when the optical device  130  is not attached to the mount  300 . 
     The optical device  130  may advantageously be a low profile night vision device as described above. Again, other viewing device configurations are contemplated and by providing three pivoting segments, the mounting system  300  may readily be tailored for use with other viewing devices, including those with widely varying profiles or dimensions. 
     As best seen in  FIG. 13 , the mounting system  300  may also be pivoted to another stowed position, wherein the second pivoting segment  322  remains in the deployed position and the third pivoting segment  326  is pivoted to the upward position. Optionally, an intermediate pivot position between the first and second pivoting segments may also be provided as described above. 
     In the illustrated preferred embodiment  300 , a tilt adjustment mechanism for adjusting the tilt angle of the optical device to a desired line of sight or optical axis is not included, since a tilt adjustment is included on the AN/PVS-21 LPNVG. However, a tilt angle adjustment knob (not shown) may optionally be provided to allow the tilt angle of the optical device  130  to be adjusted to a desired line of sight or optical axis where the unit  300  is intended to be used with an optical device that lacks an integrated tilt angle adjustment. The optional tilt angle adjustment mechanism may comprise, for example, a threaded knob rotatably engaging a threaded shaft running in an elongate or arcuate slot which may be selectively loosened for adjustment and then tightened when the tilt angle is at a desired position. If desired, the optional tilt angle adjustment mechanism may be as described in the aforementioned U.S. application Ser. No. 12/259,010 or U.S. Pat. No. 7,219,370. 
     The first pivot segment  314  includes a hinge portion  337  including openings  339 . The second pivot segment  322  includes a proximal hinge portion  341  having openings  343  and a distal hinge portion  345  having openings  347 . The third pivot segment  326  includes a hinge portion  349  having openings  351 . 
     A first hinge or pivot pin  353  includes a button  355  secured to a first end thereof, e.g., via a threaded fastener  357 . A spring pin  359  is received within an opening  361  in the pivot pin  353 . The first hinge pin  353  lies along the first pivot axis  324 . 
     A second hinge or pivot pin  363  includes a button  365  secured to a first end thereof, e.g., via a threaded fastener  367 . A spring pin  369  is received within an opening  371  in the pivot pin  363 . The second hinge pin  363  lies along the second pivot axis  328 . In the depicted embodiment, the buttons  355  and  365  are on opposite transverse sides of the unit  300  to reduce the possibility of inadvertently actuating one of the buttons  355  or  365  when actuation of the other is intended. 
     The first hinge pin  353  extends through the aligned openings  339  and  343  of the respective hinge portions  337  and  341  of the first and second pivoting segments  314  and  322 , respectively, thereby providing a hinged or pivoting connection therebetween. 
     The second hinge pin  363  extends through the aligned openings  347  and  351  of the respective hinge portions  345  and  349  of the second and third pivoting segments  322  and  326 , respectively, thereby providing a hinged or pivoting connection therebetween. 
     A first spring  373  is received within a cavity  377  in the proximal hinge portion  341  and is coaxially received about the first hinge pin  353 . A second spring  375  is received within a cavity  379  in the distal hinge portion  339  and is coaxially received about the second hinge pin  363 . 
     A first retention disk  381  is secured to the opposite end of the first hinge pin  353  via a threaded fastener  383 . A locating pin  385  is rigidly received in the openings  387  in the disk  381 , e.g., secured via retaining pin  420  engaging aligned openings  421  and  422  in the retaining disk  381  and pin  385 , respectively. Likewise, a second retention disk  391  is secured to the opposite end of the second hinge pin  363  via a threaded fastener  393 . A locating pin  395  is rigidly received in the openings  397  in the disk  391 , e.g., secured via retaining pin  420  engaging aligned openings  423  and  424  in the retaining disk  391  and pin  395 , respectively. 
     The locating pin  385  is slidably received through opening  501  in the hinge portion  339  and slidably extends into a selected one of complimentary openings  503  and  505  in the hinge portion  341 , depending on the desired pivot position. Pins  507  ride in acruate slots  509  as the second pivot segment  322  is pivoted relative to the segment  314  when the button  355  is actuated. In operation, to pivot the second pivoting segment  314  relative to the first pivoting segment  320 , the button  355  is manually depressed causing the pivot pin  353  to slide in the axial direction. The spring pin  359  engages the spring  373  and compresses the spring  373  when the button  355  is depressed. 
     As the hinge pin  353  is translated in the transverse direction along the axis  324 , the locating pin  385  is disengaged from the opening  503  or  505 , as applicable depending on initial position, in the hinge portion  341 , thereby allowing the second portion  322  to pivot with respect to the first portion  314 . After the second portion  322  is pivoted to the desired position relative to the first portion  320  and the locating pin  385  are brought into alignment with the other one of locating openings  503 ,  505 , on the hinge portion  341 . The bias of the spring  373  urges the hinge pin  353  back to its original position, causing the locating pins  385  to slidingly engage the currently aligned opening  503  or  505  in the hinge portion  341 , thereby maintaining the first and second pivoting segments  314  and  322  in a fixed relative angular orientation. 
     Similarly, the locating pin  395  is slidably received through a selected one of angularly displaced openings (not shown) formed on the hinge portion  349  and slidably extends into an opening  511  in the hinge portion  345 . The hinge portion  345  includes two openings (not shown), angularly displaced about the axis  328 , each of which corresponds to a selected angular position of the second segment  322  relative to the third segment  326 . In operation, to pivot the third pivoting segment  326  relative to the second pivoting segment  322 , the button  365  is manually depressed causing the pivot pin  363  to slide in the axial direction. The spring pin  369  engages the spring  375  and compresses the spring  375  when the button  365  is depressed. 
     As the hinge pin  363  is translated in the transverse direction along the axis  328 , the locating pin  395  is disengaged from the corresponding aligned opening (not shown) in the hinge portion  345 , thereby allowing the third portion  326  to pivot freely with respect to the second portion  322 . After the third portion  326  is pivoted to the desired position relative to the second portion  322  the locating pin  395  is brought into alignment with the other locating opening (not shown) on the hinge portion  345 . The bias of the spring  375  urges the hinge pin  363  back to its original position, causing the locating pin  395  to slidingly engage the currently aligned one of the angularly displaced openings (not shown) in the hinge portion  345 , thereby maintaining the second and third pivoting segments  322  and  326  in a fixed relative angular orientation as the desired position. 
     A carriage assembly  136  includes a sliding body  140  having rails  142  slidably received within grooves  344  formed in the third pivoting segment  326 . Sliding movement of the sliding body  140  within the channels  344  provides a fore and aft adjustment mechanism for positioning the optical device at a desired distance from the user&#39;s eyes. In the depicted preferred embodiment, the fore and aft positioning is infinitely slidably adjustable therealong. A cam lever  148  is rotatably secured to the sliding body  140  and is rotatable about a pivot pin  152 . The cam lever includes a cam peripheral surface  156  which exerts a force against the sidewall of the third pivoting segment  326  to secure the sliding body at a desired position along the third segment  326  when the cam lever is in the locked position. When the cam lever is in the unlocked position, the sliding body  140  slides freely along the third segment  326 . 
     The carriage assembly also includes an optical device mounting shoe assembly  230 , which includes a mounting shoe  240 . The mounting shoe  240  is attached to the sliding body  140  via threaded fasteners  242 . The mounting shoe  240  includes a dovetail or like receptacle  244  for removably receiving a complimentary mating mounting foot member  247  (see  FIG. 8 ) of the optical device  130 . A retention member  246  is received within an opening  245  in the mounting shoe  240 . 
     The retention member includes a forward end  248  and a rearward end  250 . A pivot pin  252  is received within channels or grooves  254  on the mounting shoe  240  and extends transversely across the aperture  245  in the mounting shoe  240 . The retention member  246  includes a groove  256  receiving the pin  252  to pivotally secure the retention member in the opening  245 . 
     A spring  258  includes a first end received within an opening  268  in the rearward end  250  of the retention member  246 . A second end of the spring  258  bears against the sliding body  140 . In operation, the spring  258  urges the rearward end  250  into a complimentary depression or opening  259  (see  FIG. 8 ) on the mounting foot portion  247  of the optical device  130 . A release button  260  is slidably received between the mounting shoe  240  and the sliding body  140 . A pair of springs  262  urges the button  260  to the locked position. 
     In operation, to remove the optical device  130  from the mounting shoe, the button  260  is manually pressed inwardly. A ramped or inclined surface  264  on the button  260  slidingly engages the forward surface  248  of the retention member  246 , urging it downward as the button  260  is depressed inward. As the retention member pivots about the pin  252 , the rearward end  250  moves upward against the bias of the spring  258 , thereby disengaging the complimentary receptacle ( 259 , see  FIG. 8 ) on the optical device  130 , allowing the optical unit  130  to be removed. 
     The invention has been described with reference to the preferred embodiments. Modifications and alterations will occur to others upon a reading and understanding of the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims.