Patent Publication Number: US-2023154120-A1

Title: Adjustable waveguide assembly and augmented reality eyewear with adjustable waveguide assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 17/394,120 filed on Aug. 4, 2021, which is a Continuation of U.S. patent application Ser. No. 16/568,450 filed on Sep. 12, 2019, now U.S. Pat. No. 11,113,889, and claims priority to U.S. Provisional Application Ser. No. 62/737,456 filed on Sep. 27, 2018, the contents of all of which are incorporated fully herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to augmented reality eyewear and, more particularly, to adjustable eyewear assemblies that can be customized for individual users. 
     BACKGROUND 
     Augmented reality (AR) is a live direct or indirect view of a physical, real-world environment whose elements are augmented (or supplemented) by computer-generated images such as video or graphics.  FIG.  1    illustrates a conventional AR display system  100  incorporated into eyewear. In the conventional AR display system  100 , a projector  102  projects light  104  containing an image into a waveguide  108  (e.g., lens  110 ). The light is projected toward an input coupler  106 , which may be in the form of diffractive grating, that bends the light in order to trap the light within the waveguide  108 . The light is internally reflected within the waveguide  108  until it encounters an output coupler  112 , which also may be in the form of diffractive grating. Output coupler  112  causes the light to exit the wave guide  108 . 
     Output coupler  112  creates a first portion of light  114  that exits lens  110  toward an eye of a user wearing the eyewear. Output coupler  112  also causes a second portion of light  116  to exit the opposite side of lens  110  away from the user&#39;s eye. The first portion of light  114  projects from lens  110  in the form of an image. To see the full image, a user&#39;s pupil needs to be positioned within an area called an “eye box”  170 . The term “eye box”, as used in the present disclosure, refers to an area in space within which a user&#39;s pupil must be positioned in order to see an image projected from the waveguide in front of that pupil. 
     The display performance of AR eyewear is impacted by different variables, including but not limited to the size and location of the eye box relative to the user&#39;s eye. Ideally, the output coupler should produce an eye box that is centered in front of the user&#39;s pupil so that the user&#39;s eye can sweep across the entire eye box and see the entire image. If the eye box is not properly positioned relative to the user&#39;s eye, the user will not see the full image. 
     The position of an eye box relative to the user&#39;s eye is dependent in part on how the eyewear is worn, and more particularly on how the lens is positioned relative to the user&#39;s eye. Display problems can arise if the eyewear does not fit the user properly, or if other factors are present that prevent the eye box from being properly positioned relative to the eye. Every user has their own unique physiological features that affect how eyewear fits, including but not limited to their head size, bone structure, facial contours, and relative positions of their eyes, ears and nose. Every user also has unique non-physiological factors that can influence how they wear eyewear, including individual preference for where eyewear sits on their head and face. For these reasons, a given set of eyewear will not fit every user the same. Therefore, the display performance of a given set of eyewear can vary greatly from user to user. 
     Some manufacturers of AR eyewear address this problem by configuring their eyewear to produce a large eye box relative to the size of the user&#39;s eye. The idea of providing a large eye box is based on the assumption that a large eye box will be more likely to overlap the optimum eye box position for a greater number of people, and therefore ensure better performance for more users. However, such a solution actually decreases performance for users in general, because a larger eye box sacrifices image quality. As the size of the eye box increases, the brightness and contrast of the resulting image decrease. 
     Other manufacturers of eyewear address the problem by offering multiple eyewear frames having different sizes. The idea of providing differently sized frames is based on the assumption that more frame sizes will result in more users finding a frame that correctly aligns the eye boxes with their eyes. However, there are many physiological and non-physiological variables that affect how eyewear fits, as noted above. Frames of different sizes only offer a limited number of solutions, making it unlikely that a user will find a size that compensates for every variable. Therefore, some users may find that their ideal frame size exists somewhere between the frame sizes that are available, preventing them from achieving an optimized eye box location. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The present disclosure is best understood from the following detailed description when read in connection with the accompanying drawings. The various features of the drawings are not drawn to scale unless otherwise indicated. Included in the drawings are the following figures: 
         FIG.  1    is a block diagram of a conventional AR display system incorporated into eyewear; 
         FIG.  2    is a perspective view of AR eyewear according to one example of the present disclosure; 
         FIG.  3    is a front view of the AR eyewear according to  FIG.  1   ; 
         FIG.  4    is a truncated and magnified view of the AR eyewear according to  FIG.  1   , shown in a first operative state; 
         FIG.  5    is a truncated and magnified view of the AR eyewear according to  FIG.  1   , shown in a second operative state; 
         FIG.  6    is a magnified perspective view of components of the AR eyewear according to  FIG.  1   ; 
         FIG.  7    is a truncated and magnified cross-section view of the AR eyewear according to  FIG.  1   , and the threaded engagement of the components of  FIG.  6   ; 
         FIG.  8    is a front view of the AR eyewear according to  FIG.  1   , being worn by a user in a first position prior to adjustment; 
         FIG.  9    is a front view of the AR eyewear according to  FIG.  1   , being worn by a user in a second position after adjustment; 
         FIG.  10    is a truncated and magnified front view of a lens portion of eyewear according to another example of the present disclosure; 
         FIG.  11    is a perspective view of AR eyewear according to another example of the present disclosure; 
         FIG.  12    is a front view of the AR eyewear according to  FIG.  11   ; 
         FIG.  13    is a truncated and magnified view of the AR eyewear according to  FIG.  11   , shown in a first operative state; 
         FIG.  14    is a truncated and magnified view of the AR eyewear according to  FIG.  11   , shown in a second operative state; 
         FIG.  15    is an exploded perspective view of components of the AR eyewear according to  FIG.  11   ; 
         FIG.  16    is a schematic top view of components of the AR eyewear according to  FIG.  11   , shown in a first operative state; 
         FIG.  17    is a schematic top view of components of the AR eyewear according to  FIG.  11   , shown in a second operative state; 
         FIG.  18    is a front view of the AR eyewear according to  FIG.  11   , being worn by a user in a first position prior to adjustment; 
         FIG.  19    is a front view of the AR eyewear according to  FIG.  11   , being worn by a user in a second position after adjustment; 
         FIG.  20    is a perspective view of AR eyewear according to another example of the present disclosure; 
         FIG.  21    is a truncated rear elevation view of AR eyewear according to yet another example of the present disclosure, wherein the nose rest is shown in a maximally lowered position; 
         FIG.  22    is a truncated isometric view of the AR eyewear of  FIG.  21   , wherein the nose rest is shown in a maximally raised position; 
         FIG.  23    is a truncated and magnified view of the AR eyewear of  FIG.  21   , wherein internal features of the AR eyewear are shown in hidden lines; 
         FIG.  24    is a truncated rear elevation view of AR eyewear according to still another example of the present disclosure; 
         FIG.  25 A  is a cross-sectional view of the AR eyewear of  FIG.  24   , wherein the nose rest is shown in a maximally raised position; and 
         FIG.  25 B  is another cross-sectional view of the AR eyewear of  FIG.  24   , wherein the nose rest is shown in a maximally lowered position. 
     
    
    
     DETAILED DESCRIPTION 
     Numerous details are set forth in the following detailed description by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details, or with the details featured in different arrangements and combinations. 
     The term “coupler” refers to any structure that facilitates or promotes the transition of light from one medium to another. When used in the context of a waveguide, couplers may be any structure created in, applied to, or otherwise formed on the waveguide which facilitates or promotes the input of light into the waveguide or the output of light from the waveguide. Couplers may be formed from the material of the waveguide, e.g., by molding or etching a surface of the waveguide to form facets, surfaces, or other structures which promote the input or output of light. Couplers may also be formed from materials or layers which are applied to a surface of the waveguide. 
       FIG.  2    depicts one example of AR eyewear  200 . Eyewear  200  includes an adjustable frame assembly  210  supporting a first waveguide  250 L and a second waveguide  250 R. First waveguide  250 L includes a first lens  260 L. First lens  260 L has a first output coupler  265 L for producing a first eye box  270 L. Second waveguide  250 R includes a second lens  260 R. Second lens  260 R has a second output coupler  265 R for producing a second eye box  270 R. Frame assembly  210  is operable to adjust and fine tune the vertical position of the first and second lenses  260 L,  260 R relative to the user&#39;s field of vision so as to optimize the vertical positions of first and second output couplers  265 L,  265 R, and consequently the vertical positions of eye boxes  270 L,  270 R. The term “vertical”, as used in the present disclosure, refers to the up-down direction defined between a top edge of the frame assembly and the bottom edge of the frame assembly. The vertical direction in each lens  260 L,  260 R is depicted in  FIG.  2    by the double-ended arrows labeled “V”. 
     Frame assemblies according to the present disclosure can include various movable or fixed components for holding eyewear on the users face. In the present example, frame assembly  210  includes a first temple or arm  220 L and a second temple or arm  220 R. First and second temples  220 L,  220 R include respective end pieces  222 L,  222 R that are curved to fit around the user&#39;s ears. Frame assembly also includes a first housing  230 L and a second housing  230 R. First housing  230 L has a first end  232 L fixedly attached to first temple  220 L, and a second end  234 L opposite first end  232 L. Likewise, second housing  230 R has a first end  232 R fixedly attached to first temple  220 R, and a second end  234 R opposite first end  232 R. 
       FIG.  3    provides a front view of frame assembly  210 . For clarity purposes, certain features shown in  FIG.  2    are omitted in  FIG.  3   . Frame assembly  210  includes a face portion  240  that contains first lens  260 L and second lens  260 R. Face portion  240  includes a first end  242 L and a second end  242 R opposite first end  242 L. First end  242 L is fixedly attached to second end  234 L of first housing  230 L, and second end  242 R is fixedly attached to second end  234 R of second housing  230 R. Face portion  240  defines a first rim  243 L that houses first lens  260 L, and a second rim  243 R that houses second lens  260 R. Face portion  240  also defines a centrally located bridge  244  that interconnects first rim  243 L and second rim  243 R. 
     Frame assemblies in accordance with the present disclosures can have a variety of configurations and components that allow the face portion to be supported on the user&#39;s nose. For example, various types of support rests can be used to support the face portion on the top of the user&#39;s nose. Support rests according to the present disclosure can have one or more elements that provide one or more points of contact on the wearer&#39;s face. In addition, support rests according to the present disclosure can have various degrees of flexibility, softness, padding and surface textures. For example, support rests according to the present disclosure can be formed of a soft material, including but not limited to soft silicone, or include one or more pads made of such a material. 
     In the present example, frame assembly  210  has a support rest in the form of a nose rest  280  having an inverted U-shaped body  282  ( FIG.  6   ). Nose rest  280  is connected to bridge  244  and extends into a notch or recess  246  formed by first rim  243 L, second rim  243 R and bridge  244 . In this position, nose rest  280  is configured to rest on top of the user&#39;s nose when eyewear  200  is placed on the user&#39;s face. As such, frame assembly  210  has three support points when it is worn as intended: (1) first temple  220 L which rests on top of the user&#39;s left ear, (2) second temple  220 R which rests on top of the user&#39;s right ear, and (3) nose rest  280  which rests on top of the user&#39;s nose. 
     Face portion  240  has a top edge  240 T and a bottom edge  240 B opposite the top edge. Bottom edge  240 B extends along adjoining edges of first rim  243 L, bridge  244 , and second rim  243 R. In this arrangement, bottom edge  240 B borders recess  246  on three sides. Nose rest  280  connects to bridge  244  at bottom edge  240 B by an adjustable coupling  290 . 
     Adjustable coupling  290  is operable to adjust the relative position of nose rest  280  relative to face portion  240  of frame assembly  210 . In particular, adjustable coupling  290  is operable to move nose rest  280  relative to face portion  240  in a first direction, which decreases the relative spacing between the nose rest and bridge  244 , and a second direction, which increases the relative spacing between the nose rest and bridge. In this arrangement, nose rest  280  is movable relative to bridge  244  between a maximum raised position, shown in  FIG.  4    and a maximum lowered position, shown in  FIG.  5   . By changing the relative spacing between nose rest  280  and bridge  244 , the vertical positions of first and second output couplers  265 L,  265 R and their respective eye boxes  270 L,  270 R can be adjusted until the eye boxes are vertically centered relative to the user&#39;s pupils. 
     Frame assemblies and eyewear according to the present disclosure can include any type of adjustable coupling to adjust the vertical position of the face portion relative to the nose rest (or other type of support). Referring to  FIGS.  6  and  7   , adjustable coupling  290  includes a two part assembly featuring a threaded post  292  extending from nose rest  280  and a thumb wheel or dial  294 . Threaded post  292  is generally rectangular in cross section, with two opposing sides each bearing a rounded contour and threads. Dial  294  has a ring shaped body  296  that defines a bore hole  298 . Bore hole  298  has an internal thread  299 . Bridge  244  defines a rectangular passage  245  defining a longitudinal axis  247  and a radially relieved section  248  along a midsection of the passage. Dial  294  is captively held in radially relieved section  248 , with bore hole  298  axially aligned with longitudinal axis  247  of passage  245 . In this arrangement, dial  294  can rotate in bridge  244  but remains axially fixed, while threaded post  292  can move axially in passage  245  but is fixed against rotation relative to the passage. 
     Threaded post  292  has an external thread  293  configured to mate with internal thread  299  of dial  294 . As such, threaded post  292  can be advanced into passage  245  and threaded into bore hole  298  of dial  294 . The threaded engagement between threaded post  292  and dial  294  allows the post to be axially displaced in passage  245  when the dial is rotated. Passage  245  is sufficiently long to receive most or all of the length of threaded post  292 . 
     Radially relieved section  247  connects to the exterior of bridge  244  through opposing apertures  249 , one aperture on the front of face portion  240  and the other aperture on the rear of the face portion. A portion of dial  294  projects through each aperture  249  where the portion is exposed on the exterior of bridge  244 . With this arrangement, a user can rotate dial  294  with his or her fingers and/or thumb. Rotation of dial  294  will axially displace threaded post  292  within passage  245  and move face portion  240  relative to nose rest  280 . 
     When frame assembly  210  is worn by a user, with nose rest  280  resting on the user&#39;s nose, movement of face portion  240  toward the nose rest has the effect of the moving bottom edge  240 B closer to the user&#39;s nose. This direction of movement of face portion  240  will be referred to as “down” or the “downward direction.” Conversely, when frame assembly  210  is worn by the user, with nose rest  280  resting on the user&#39;s nose, movement of face portion  240  away from the nose rest has the effect of moving bottom edge  240 B away from the user&#39;s nose. This direction of movement of face portion  240  will be referred to as “up” or the “upward direction.” 
     Dial  294  is rotatable in a first direction to move face portion  240  in the downward direction, and a second direction opposite the first direction to move the face portion in the upward direction. Dials according to the present disclosure can have ridges, knurling or other surface features that help the user&#39;s finger tips grip the dial and reduce finger slippage. In the present example, dial  294  has a plurality of ribs  295  extending around the outer surface of the dial to make the surface easier to grip and rotate. 
     Eyewear according to the present disclosure can each be provided with a set of nose rests, each nose rest having a body with a unique shape and fit. Each of the nose rests can be configured for attachment to the face portion by inserting the threaded post into the passage and rotating the dial in a first direction to draw the threaded post into the bridge. Each nose rest can also be removed from the face portion by rotating the dial in a second direction opposite the first direction until the threaded post completely exits the bridge, at which time, the nose rest can be replaced with a different nose rest in the set. This allows users to try different nose rests and choose a nose rest that feels comfortable on their nose. 
     Nose rests according to the present disclosure can also include an asymmetrical body design that features a front side and a rear side having a different contour than the front side. This provides each nose rest with two different surface profiles, one on the front side and the other on the rear side, with each surface profile configured to rest on the user&#39;s nose differently. Referring to  FIG.  6   , for example, nose rest  280  has a first side  284  with a first profile and a second side  286  opposite the first side with a second profile different from the first profile. This asymmetry allows the user to utilize nose rest  280  in a first orientation with the first side  284  contacting their nose, or in a second orientation with the second side  286  contacting their nose. If the user finds that the first side  284  is uncomfortable against their nose, then the user can remove nose rest  280  from face portion  240 , rotate the nose rest 180 degrees, and reinsert the nose rest into the face portion with the second side  286  against their nose. 
     Eyewear according to the present disclosure can feature either conventional or customized components for projecting light images through the lenses. Referring back to  FIGS.  2  and  3   , first housing  230 L contains a first projector  236 L, and second housing  230 R contains a second projector  236 R. First projector  236 L is operable to project light containing an image toward an input coupler  252 L in first lens  260 L. Similarly, second projector  236 R is operable to project light containing an image toward an input coupler  252 R in second lens  260 R. First and second input couplers  252 L,  252 R bend light to trap the light within first and second waveguides  260 L,  260 R, respectively. Light is internally reflected within first and second waveguides  260 L,  260 R until the light encounters output couplers  265 L,  265 R, causing the light to exit lenses  260 L,  260 R. A portion of the exiting light is directed toward the user&#39;s eyes and visible in eye boxes  270 L,  270 R. 
     Eyewear and frame assemblies according to the present disclosure can be placed on a user&#39;s head in the same manner as conventional eyeglasses. In the present example, a user can place eyewear  200  on his/her head by placing first temple  220 L over their left ear and placing right temple  220 R over their right ear. The user then lowers first temple  220 L and second temple  220 R onto the left ear and right ear, respectively, until the first and second temples rest on top of each ear behind the helix. Portions of end pieces  222 L,  222 R may also rest on top of the ear and/or extend around the ear behind the helix. Face portion  240  is lowered onto the user&#39;s nose until nose rest  280  rests on top of the nose, with first lens  260 L in front of the left eye and second lens  260 R in front of the right eye. In this arrangement, eyewear  200  is supported in a stable position on the user&#39;s left ear, right ear and nose. 
     Eyewear  200  is powered on in a conventional manner to activate first and second projectors  236 L,  236 R and produce images in first and second eye boxes  270 L,  270 R. The user&#39;s bone structure, facial features, or other physiological or non-physiological factors can initially cause first and second eye boxes  270 L,  270 R to be positioned too high or too low relative to the user&#39;s pupils. In such a case, the relative positions of first and second eye boxes  270 L,  270 R can be fine-tuned using adjustable coupling  290  until each eye box is positioned at the optimum vertical position for the user. 
     For example, if each eye box  270 L,  270 R is positioned too high relative to the user&#39;s eye, the user can fine tune the position of each eye box by rotating dial  294  in the first direction. This action will move face portion  240  down, and consequently move output couplers  265 L,  265 R and their respective eye boxes  270 L,  270 R down. Conversely, if each eye box  270 L,  270 R is positioned too low relative to the user&#39;s eye, the user can fine tune the position of each eye box by rotating dial  294  in the second direction opposite the first direction. This action will move face portion  240  up, and consequently move output couplers  265 L,  265 R and their respective eye boxes  270 L,  270 R up. Depending on whether eye boxes  270 L,  270 R are too high or too low, the user rotates the dial in the first direction or second direction until the user can see the full images in the eye boxes. 
       FIGS.  8  and  9    illustrate the relative positions of face portion  240  and eye boxes  270 L,  270 R before and after adjustment. Some features of eyewear  200 , such as output couplers  265 L,  265 R, are omitted for clarity. 
       FIG.  8    depicts a scenario in which eyewear  200  is placed on the user&#39;s face without any adjustment. The projectors  236 L,  236 R are powered on to produce images in first and second eye boxes  270 L,  270 R. In this scenario, first and second eye boxes  270 L,  270 R are beneath the user&#39;s pupils. Therefore, the user will not be able to see complete images. This is due to the relative positions of lenses  260 L,  260 R and eye boxes  270 L,  270 R, which are positioned too low relative to the user&#39;s pupils. 
     To correct this condition, the user can rotate dial  294  to move frame portion  240  up until eye boxes  270 L,  270 R are aligned with the user&#39;s pupils.  FIG.  9    shows the same eyewear  200  on the same user after face portion  240  has been adjusted using adjustment coupling  290 . As can be seen, face portion  240  and eye boxes  270 L,  270 R have moved upwardly with respect to nose rest  280 . In this adjusted position, first and second eye boxes  270 L,  270 R are vertically centered in optimized positions in front of the user&#39;s pupils so that the user can see the full image in each eye box. 
     The thread pitches of external thread  293  and internal thread  299  are preferably small so that each 360 degree revolution of dial  294  only moves first and second eye boxes  270 L,  270 R a small distance up or down. For example, the thread pitch can be in the range of 0.3 mm-1.0 mm. Other thread pitches can also be used with suitable results. A small thread pitch permits very fine adjustment of the vertical position of eye boxes, and also prevents significant changes in vertical position when dial  294  is inadvertently bumped or touched, such as when the user takes the eyewear off or when the eyewear is being handled. 
     The threaded engagement between nose rest  280  and bridge  244  has the advantage of providing continual vertical adjustment of first and second eye boxes  270 L,  270 R. First and second eye boxes  270 L,  270 R can be vertically adjusted through an infinite number of vertical positions, allowing each user to achieve a customized fit that provides optimized vertical positioning of the eye boxes. The ability to optimize the vertical positions of eye boxes  270 L,  270 R avoids the need to design and manufacture multiple different frame sizes. The ability to optimize the vertical positions of eye boxes  270 L,  270 R also avoids the need to provide large eye boxes to accommodate different users. In fact, the sizes of eye boxes and output couplers can be reduced because the ability to fine tune the vertical positions of eye boxes makes it possible to align a much smaller eye box to any eye. It has been found that an output coupler that is 14 mm wide×9 mm high can be reduced to a size of 14 mm wide×4 mm high when vertical adjustment is provided. This reduction reduces the height of each eye box by 5 mm, resulting in an overall size reduction of approximately 55.6% for each eye box. Although each eye box is much smaller in the vertical direction, the eyewear still accommodates many different users because the smaller eye boxes can be vertically centered relative to the user&#39;s pupils. 
       FIG.  10    schematically illustrates how eye box size can be reduced in eyewear  300  according to the present disclosure. Eyewear  300  has a face portion  340  containing a lens  360 . Lens  360  includes a rectangular output coupler  365  with a top edge  365 T. If eyewear  300  does not have an adjustment mechanism for adjusting the vertical position of face portion  340 , then a larger output coupler will be required to produce a sufficiently large eye box that accommodates different users. A larger output coupler is depicted in  FIG.  10    with its bottom edge  365 B shown by a dashed line. 
     If eyewear  300  is equipped with an adjustment coupling (e.g. adjustment coupling  290 ), then the height of output coupler  365  does not need to be as large. Therefore, the bottom edge of output coupler  365  can be moved closer to top edge  365 T, as shown by the arrow and solid line  365 C which represents the bottom edge of the smaller eye box. Moving the bottom edge closer to top edge  365 T results in an output coupler and eye box with a smaller height H. The cross hatched area represents the portion of output coupler that is eliminated. 
     As noted above, the brightness and contrast of images degrade as the size of eye boxes increase. Therefore, brightness and contrast can improve by decreasing the vertical dimension of each eye box. The inventors have observed a 30% improvement in brightness in each eye box when the size of each eye box size is decreased from 14 mm wide×9 mm high to 14 mm wide×4 mm high. In view of the improved image quality, the required light intensity to produce an image of good quality is decreased. Therefore, the amount of input power required to produce a quality image is also decreased, resulting in less power consumption and longer battery life. 
     Frame assemblies and eyewear according to the present disclosure can include a variety of adjustable couplings to adjust the vertical position of the face portion, as noted above. Therefore, the adjustable couplings are not limited to threaded posts and dials and include other mechanisms that permit vertical adjustment of the face portion. For example, alternative eyewear according to the present disclosure can be identical in all respects to eyewear  200 , except that the adjustable coupling features a ratchet and pawl to adjust the position of the bridge relative to nose rest. The pawl can be housed inside the bridge, and the ratchet can engage the pawl inside the bridge. This arrangement allows the adjustment coupling to be partially or completely concealed inside the bridge, thereby providing a more aesthetic appearance to the frame. 
     Eyewear and frame assemblies according to the present disclosure can also include mechanisms that allow users to adjust and fine tune the horizontal positions of eye boxes. Mechanisms for adjusting the horizontal position of an eye box according to the present disclosure work independently of mechanisms for adjusting the vertical position. Therefore, eyewear according to the present disclosure can include a horizontal adjustment mechanism in combination with a vertical adjustment mechanism, allowing the user to optimize both the horizontal and vertical position of an eye box. Alternatively, eyewear according to the present disclosure can feature only a horizontal adjustment mechanism or feature only a vertical adjustment mechanism. 
       FIG.  11    depicts one example of AR eyewear  1200  that includes only a horizontal adjustment feature. Eyewear  1200  includes a frame  1202  that defines a first socket  1204  and a second socket  1206 . First socket  1204  supports a first waveguide  1250 L in a movable arrangement, as will be described. In addition, first socket  1204  has a first or “left” side  1204 L and a second or “right” side  1204 R opposite the left side. Frame  1202  also defines a second socket  1206  that supports a second waveguide  1250 R in a movable arrangement, as will be described. Second socket  1206  has a first or “left” side  1206 L and a second or “right” side  1206 R opposite the left side, analogous to first socket  1204 . 
     First waveguide  1250 L is in the form of a first lens  1260 L. First lens  1260 L has a first output coupler  1265 L for producing a first eye box  1270 L. Second waveguide  1250 R is in the form of a second lens  1260 R. Second lens  1260 R has a second output coupler  1265 R for producing a second eye box  1270 R. Eyewear  1200  also includes a horizontal adjustment assembly  1290 , which is operable to adjust and fine tune the horizontal positions of first and second lenses  1260 L,  1260 R relative to the user&#39;s field of vision. Horizontal adjustment assembly  1290  ( FIG.  12   ) allows a user to optimize the horizontal positions of first and second output couplers  1265 L,  1265 R, and consequently the horizontal positions of eye boxes  1270 L,  1270 R relative to each eye. 
     The term “horizontal”, as used in the present disclosure, refers to the left-right direction extending between left side  1204 L and right side  1204 R of first socket  1204 , and the left-right direction extending between left side  1206 L and right side  1206 R of second socket  1206 . The horizontal direction in each of sockets  1204 ,  1206  is identified by the double-ended arrows labeled “H” in  FIG.  11   . 
     Frame  1202  includes a first temple or arm  1220 L and a second temple or arm  1220 R. First and second temples  1220 L,  1220 R include respective end pieces  1222 L,  1222 R that are curved to fit around the user&#39;s ears. Frame  1202  also includes a first housing  1230 L and a second housing  1230 R. First housing  1230 L has a first end  1232 L fixedly attached to first temple  1220 L, and a second end  1234 L opposite first end  1232 L. Likewise, second housing  1230 R has a first end  1232 R fixedly attached to first temple  1220 R, and a second end  1234 R opposite first end  1232 R. 
     Referring to  FIG.  12   , frame  1202  further includes a face portion  1240  that contains first lens  1260 L and second lens  1260 R. Face portion  1240  includes a first end  1242 L and a second end  1242 R opposite first end  1242 L. First end  1242 L is fixedly attached to second end  1234 L of first housing  1230 L, and second end  1242 R is fixedly attached to second end  1234 R of second housing  1230 R. Face portion  1240  defines a first rim  1243 L that houses first lens  1260 L, and a second rim  1243 R that houses second lens  1260 R. Face portion  1240  also defines a centrally located bridge  1244  that interconnects first rim  1243 L and second rim  1243 R. 
     As noted above, frames according to the present disclosure can have a variety of configurations and components that allow the face portion to be supported on the user&#39;s head and face. For example, various types of support rests can be used to support the face portion on the top of the user&#39;s nose. In the present example, lower edges of first rim  1243 L, second rim  1243 R and bridge  1244  form a nose rest  1280  that supports frame  1202  on the user&#39;s nose. First rim  1243 L, second rim  1243 R and bridge  1244  border a notch or recess  1246  which accommodates the user&#39;s nose. In this arrangement, frame  1202  has three support points when it is worn as intended: (1) first temple  1220 L which rests on top of the user&#39;s left ear, (2) second temple  1220 R which rests on top of the user&#39;s right ear, and (3) nose rest  1280  which rests on top of the user&#39;s nose. 
     Face portion  1240  has a top edge  1240 T and a bottom edge  1240 B opposite the top edge. Bottom edge  1240 B extends along adjoining edges of first rim  1243 L, bridge  1244 , and second rim  1243 R. In this arrangement, bottom edge  1240 B borders recess  246  on three sides. 
     Horizontal adjustment assembly  1290  is operable to adjust the horizontal positions of each waveguide  1250 L,  1250 R relative to frame  1202 . In particular, horizontal adjustment assembly  1290  is operable to move waveguide  1250 L in the horizontal direction relative to first rim  1243 L and move waveguide  1250 R in the horizontal direction relative to second rim  1243 R. In this arrangement, horizontal adjustment assembly  1290  is operable to move first waveguide  1250 L toward left side  1204 L of first socket  1204  or move the first waveguide toward right side  1204 R of the first socket. Likewise, horizontal adjustment assembly  1290  is operable to move second waveguide  1250 R horizontally toward left side  1206 L of second socket  1206  or move the second waveguide horizontally toward right side  1206 R of the second socket. This has the effect of moving first and second output couplers  1265 L,  1265 R and the corresponding eye boxes  1270 L,  1270 R in the horizontal direction relative to frame  1202 . 
     First waveguide  1265 L is movable inside first socket  1204  between a leftmost position, shown in  FIG.  13   , and a rightmost position, shown in  FIG.  14   . Second waveguide  1265 R is moveable to a rightmost position and a leftmost position that are mirror images of the positions shown in  FIGS.  13  and  14   , respectively. By changing the relative horizontal position of each waveguide,  1265 L,  1265 R, the relative position of each eye box  1270 L,  1270 R can be adjusted until the eye boxes are horizontally centered with respect to the user&#39;s pupils. 
     Frame assemblies and eyewear according to the present disclosure can include any type of adjustable coupling to adjust the horizontal position of a waveguide relative to the frame. Options include a threaded post/thumb wheel combination or a ratchet/pawl arrangement, similar to adjustable couplings  290 ,  290 ′. In the present example, horizontal adjustment assembly  1290  includes a first adjustment coupling  1290 L that controls the horizontal position of first waveguide  1265 L, and a second adjustment coupling  1290 R that controls the horizontal position of second waveguide  1265 R. First and second waveguides  1265 L,  1265 R and their respective adjustment couplings  1290 L,  1290 R are arranged in a mirrored arrangement. 
     Referring to  FIGS.  13 - 15   , first adjustment coupling  1290 L includes a threaded post  1292 L extending from first waveguide  1265 L and a thumb wheel or dial  1294 L. Similarly, second adjustment coupling  1290 R includes a threaded post  1292 R extending from second waveguide  1265 R and a thumb wheel or dial  1294 R. Dials  1294 L,  1294 R have ring shaped bodies  1296 L,  1296 R that define bore holes  1298 L,  1298 R, respectively. Bore holes  1298 L,  1298 R have internal threads  1299 L,  1299 R. Face portion  1240  forms a first passage  1245 L defining a longitudinal axis  1247 L and a radially relieved section  1248 L along a midsection of the passage. Face portion  1240  also forms a second passage  1245 R defining a longitudinal axis  1247 R and a radially relieved section  1248 R along a midsection of the passage. Dials  1294 L,  1294 R are captively held in radially relieved sections  1248 L,  1248 R, respectively. Bore holes  1298 L,  1298 R are axially aligned with longitudinal axes  1247 L,  1247 R, respectively. In the captive positions, dials  1294 L,  1294 R can rotate in face portion  1240  but remain axially fixed in their respective passages  1245 L,  1245 R. Dials  1294 L,  1294 R each have a plurality of ribs  1295  extending around their outer surfaces to make the dials easier to grip and rotate, similar to dial  294 . 
     Threaded posts  1292 L,  1292 R have external threads  1293 L,  1293 R, respectively. External threads  1293 L,  1293 R are respectively configured to mate with internal threads  1299 L,  1299 R of dials  1294 L,  1294 R. As such, threaded posts  1292 L,  1292 R can be advanced into passages  1245 L,  1245 R and threaded into bore holes  1298 L,  1298 R of dials  1294 L,  1294 R. The threaded engagements between threaded posts  1292 L,  1292 R and dials  1294 L,  1294 R allow the posts to be axially displaced in passages  1245 L,  1245 R when the dials are rotated. Passages  1245 L,  1245 R are sufficiently long to receive most or all of the lengths of their respective posts  1292 L,  1292 R. 
     Radially relieved sections  1248 L,  1248 R each connect to the exterior of face portion  1240  through apertures  1249 L,  1249 R which open on the front of the face portion and rear of the face portion. A portion of each dial  1294 L,  1294 R projects through their respective aperture  1249 L,  1249 R so that the portion is exposed on the exterior of face portion  1240 . With this arrangement, a user can rotate each dial  1294 L,  1294 R with his or her finger and/or thumb. Rotation of dial  1294 L will axially displace threaded post  1292 L within passage  1245 L and move first waveguide  1250 L relative to frame  1202 . Rotation of dial  1294 R will axially displace threaded post  1292 R within passage  1245 R and move second waveguide  1250 R relative to frame  1202 . 
     Dials  1294 L,  1294 R are oriented with their axes of rotation extending in the horizontal direction. Each dial  1294 L,  1294 R can be rotated in a first direction by placing a finger or thumb on the dial and moving the finger or thumb in an upward motion relative to frame  1202 . Conversely, each dial  1294 L,  1294 R can be rotated in a second direction opposite the first direction by placing a finger or thumb on the dial and moving the finger or thumb in a downward motion relative to frame  1202 . 
     In some applications, it may be desirable to configure the adjustment couplings  1290 L,  1290 R so that rotation of each dial  1294 L,  1294 R in a specific direction moves the corresponding waveguides  1265 L,  1265 R in the same direction. For example, adjustment couplings  1290 L,  1290 R can be configured so that rotating each dial  1294 L,  1294 R in a first direction moves waveguides  1265 L,  1265 R toward the left sides  1204 L,  1206 L of first and second sockets  1204 ,  1206 . In addition, adjustment couplings  1290 L,  1290 R can be configured so that rotating each dial  1294 L,  1294 R in a second direction moves waveguides  1265 L,  1265 R toward the right sides  1204 R,  1206 R of first and second sockets  1204 ,  1206 . To accomplish this, external thread  1293 L and external thread  1293 R are oriented in the same direction, rather than in a mirror arrangement. 
     Movement of dials  1294 L,  1294 R in a first direction of rotation has the effect of moving first and second waveguides  1265 L,  1265 R toward left sides  1204 L,  1206 L of sockets  1204 ,  1206 . This direction of movement of first and second waveguides  1265 L,  1265 R will be referred to as “left” or the “left direction”, which is depicted by the arrow in  FIG.  13   . Conversely, movement of dials  1294 L,  1294 R in a second direction of rotation has the effect of moving first and second waveguides  1265 L,  1265 R toward right sides  1204 R,  1206 R of sockets  1204 ,  1206 . This direction of movement of first and second waveguides  1265 L,  1265 R will be referred to as “right” or the “right direction”, which is depicted by the arrow in  FIG.  14   . 
     Eyewear according to the present disclosure can feature conventional or customized components for projecting light images through the lenses. Referring to  FIGS.  11  and  15   , first housing  1230 L contains a first projector  1236 L, and second housing  1230 R contains a second projector  1236 R. First projector  1236 L is operable to project light into first waveguide  1250 L, and second projector  1236 R is operable to project light into second waveguide  1250 R. 
     Light is projected from first and second projectors  1236 L,  1236 R into first and second waveguides  1250 L,  1250 R through two pairs of prisms. In particular, light from first projector  1236 L is projected through a first prism pair  1253 L into first waveguide  1250 L, and light from second projector  1236 R is projected through a second prism pair  1253 R into second waveguide  1250 R. First prism pair  1253 L includes a first prism  1255 L contained in frame  1202  and a second prism  1257 L attached to first waveguide  1250 L. Similarly, second prism pair  1253 R includes a first prism  1255 R contained in frame  1202  and a second prism  1257 R attached to second waveguide  1250 R. 
     During operation, light from first projector  1236 L travels into first prism  1255 L and contacts a mirror that reflects the light parallel to first waveguide  1250 L. Likewise, light from second projector  1236 R travels into first prism  1255 R and contacts a mirror that reflects the light parallel to second waveguide  1250 R. The light exits first prisms  1255 L,  1255 R orthogonal to the output surface of each prism, thereby eliminating refraction losses. Light from first prism  1255 L enters second prism  1257 L, and light from first prism  1255 R enters second prism  1257 R. The light enters second prisms  1257 L,  1257 R in a direction orthogonal to the input surface of each prism and bounces off a mirror in each prism. Light exits second prism  1257 L and enters first waveguide  1250 L at a predetermined angle, and light exits second prism  1257 R and enters second waveguide  1250 R at a predetermined angle. The light in first waveguide  1250 L travels until it reaches first output coupler  1265 L, where it exits first lens  1260 L. Light in second waveguide  1250 R travels until it reaches second output coupler  1265 R, where it exits second lens  1260 R. 
     Second prism  1257 L is attached to first waveguide  1250 L, and second prism  1257 R is attached to second waveguide  1250 R. Therefore, adjustment coupling  1290 L is operable to move second prism  1257 L relative to first prism  1255 L during horizontal adjustment of first waveguide  1250 L. Similarly, adjustment coupling  1290 R is operable to move second prism  1257 R relative to first prism  1255 R during horizontal adjustment of second waveguide  1250 R.  FIGS.  16  and  17    illustrate the movable relationship between first prism  1255 R and second prism  1257 R associated with second waveguide  1250 R. In  FIG.  16   , dial  1294 R has been rotated to position second waveguide  1250 R in the rightmost position. In this position, first prism  1255 R is positioned approximately adjacent to second prism  1257 R. In  FIG.  17   , dial  1294 R has been rotated to position second waveguide  1250 R in the leftmost position. In this position, second prism  1257 R is moved farther away from first prism  1255 R, having traveled to the left with second waveguide  1250 R. This has the effect of moving second output coupler  1265 R and eye box  1270 R toward left side  1206 L of second socket  1206 . Eye box  1270 R can be moved from this position to the right by rotating dial  1294 R until the eye box  1270 R is in an optimized horizontal position. 
     Eyewear  1200  can be placed on a user&#39;s head in the same manner as eyewear  200 . For example, a user can place eyewear  1200  on his/her head by placing first temple  1220 L over their left ear and placing right temple  1220 R over their right ear. The user then lowers first temple  1220 L and second temple  1220 R onto the left ear and right ear, respectively, until the first and second temples rest on top of each ear behind the helix. Portions of end pieces  1222 L,  1222 R may also rest on top of the ear and/or extend around the ear behind the helix. Face portion  1240  is lowered onto the user&#39;s nose until bottom edge  1240 B rests on top of the nose, with first lens  1260 L in front of the left eye and second lens  1260 R in front of the right eye. In this arrangement, eyewear  1200  is supported in a stable position on the user&#39;s left ear, right ear and nose. 
     Eyewear  1200  is powered on in a conventional manner to activate first and second projectors  1236 L,  1236 R and produce images in first and second eye boxes  1270 L,  1270 R. The user&#39;s bone structure, facial features, or other physiological or non-physiological factors can initially cause first and second eye boxes  1270 L,  1270 R to be too far to the left or too far to the right relative to the user&#39;s pupils. In such a case, the relative positions of first and second eye boxes  1270 L,  1270 R can be fine-tuned using adjustable couplings  1290 L,  1290 R until each eye box is positioned at the optimum horizontal position for the user. 
     For example, if each eye box  1270 L,  1270 R is positioned too far to the right relative to the user&#39;s eye, the user can fine tune the position of each eye box by rotating dials  1294 L,  1294 R in a first direction. This action will move first waveguide  1250 L and second waveguide  1250 R toward the left sides  1204 L,  1206 L of first and second sockets  1204 ,  1206 , respectively, thereby moving eye boxes  1270 L,  1270 R to the left. Conversely, if each eye box  1270 L,  1270 R is positioned too far to the left relative to the user&#39;s eye, the user can fine tune the position of each eye box by rotating dials  1294 L,  1294 R in a second direction opposite the first direction. This action will move first waveguide  1250 L and second waveguide  1250 R toward the right sides  1204 R,  1206 R of first and second sockets  1204 ,  1206 , respectively, thereby moving eye boxes  1270 L,  1270 R to the right. Depending on whether eye boxes  1270 L,  1270 R are too far left or too far right, the user rotates the dial in the first direction or second direction until the user can see the full images in the eye boxes. 
       FIGS.  18  and  19    illustrate the relative positions of face portion  1240  and eye boxes  1270 L,  1270 R before and after adjustment. Some features of eyewear  1200 , such as output couplers  1265 L,  1265 R, are omitted for clarity. 
       FIG.  18    depicts a scenario in which eyewear  1200  is placed on the user&#39;s face without any adjustment. The projectors  1236 L,  1236 R are powered on to produce images in first and second eye boxes  1270 L,  1270 R. In this scenario, first and second eye boxes  1270 L,  1270 R are too far to the left relative to the user&#39;s pupils. Therefore, the user will not be able to see complete images. To correct this condition, the user can rotate dial  1294 L to move first waveguide  1250 L to the right until eye box  1270 L is aligned with the user&#39;s left eye. In addition, the user can rotate dial  1294 R to move second waveguide  1250 R to the right until eye box  1270 R is aligned with the user&#39;s right eye.  FIG.  19    shows the same eyewear  1200  on the same user after first and second waveguides  1250 L,  1250 R have been adjusted. As can be seen, eye boxes  1270 L,  1270 R have both moved to the right relative to the user&#39;s eyes. In this adjusted position, first and second eye boxes  1270 L,  1270 R are horizontally centered in optimized positions in front of the user&#39;s pupils so that the user can see the full image in each eye box. 
     As with previous embodiments, the thread pitches of external threads  1293 L,  1293 R and internal threads  1299 L,  1299 R are preferably small. In this arrangement, each 360 degree revolution of dials  1294 L,  1294 R only moves first and second waveguides  1270 L,  1270 R a small distance left or right. The thread pitch can be in the range of 0.3 mm-1.0 mm, for example. Other thread pitches can also be used with suitable results. A small thread pitch permits very fine adjustment of the horizontal position of eye boxes, and also prevents significant changes in horizontal position when dials  1294 L,  1294 R are inadvertently bumped or touched, such as when the user takes the eyewear off or when the eyewear is being handled. 
     The threaded engagement between frame  1202  and first and second waveguides  1250 L,  1250 R has the advantage of providing continual horizontal adjustment of first and second eye boxes  1270 L,  1270 R. First and second eye boxes  1270 L,  1270 R can be horizontally adjusted through an infinite number of horizontal positions, and can be adjusted independently of one another, so that each eye box can be adjusted by a different amount or the same amount. This ability to adjust the horizontal position of each eye box  1270 L,  1270 R allows each user to achieve a customized fit that provides optimized horizontal positioning of the eye boxes. As noted above, the ability to optimize the horizontal position of eye boxes  1270 L,  1270 R avoids the need to design and manufacture multiple different frame sizes. The ability to optimize the horizontal position of eye boxes  1270 L,  1270 R also avoids the need to provide large eye boxes to accommodate different users. In fact, the horizontal dimension of eye boxes and output couplers can be reduced because the ability to fine tune the horizontal positions of eye boxes makes it possible to align a much narrower eye box to any eye. It has been found than an output coupler that is 14 mm wide×9 mm wide can be reduced directly proportional to horizontal adjustment provided by this mechanism. For example, if the mechanism provided 2 mm of horizontal travel, then the output coupler could be reduced to 14 mm×7 mm. 
     In certain applications, it can be desirable to provide mechanisms that adjust both the vertical and horizontal positions of eye boxes. Therefore, eyewear according to the present disclosure can include vertical and horizontal adjustment mechanisms in combination. For example, eyewear according to the present disclosure can include both the adjustment coupling  290  shown on eyewear  200 , and adjustment couplings  1290 L,  1290 R shown on eyewear  1200 .  FIG.  20    shows one example of eyewear  2200  that utilizes a vertical adjustment coupling  2290  analogous to adjustment coupling  290 , and horizontal adjustment couplings  2290 L,  2290 R that are analogous to adjustment couplings  1290 L,  1290 R. Adjustment couplings  2290 ,  2290 L,  2290 R operate independently of one another. Therefore, the trio of adjustment couplings  2290 ,  2290 L,  2290 R can cooperate together to allow the user to optimize both the vertical and horizontal positions of each eye box. Eyewear  2200  has a frame  2202  supporting first and second waveguides  2250 L,  2250 R which are configured identically to waveguides  1250 L,  1250 R. Other components of eyewear  2200  are identical to the components previously described in eyewear  200  and  1200 , and therefore will not be described. 
       FIGS.  21 - 23    depict an example of eyewear  3200  that utilizes a vertical adjustment coupling  3290  analogous to vertical adjustment coupling  290 . Vertical adjustment coupling  3290  includes a multi-part assembly featuring a ribbed post  3292  extending from nose rest  3280  that interacts with two opposing springs  3282  that are positioned within the bridge  3244  of the eyewear  3200 . Interaction between the post  3292  and the springs  3282  controls vertical adjustment of the nose rest  3280  with respect to the bridge  3244 . 
     Bridge  3244  of the eyewear  3200  defines an interior rectangular passage  3245  for receiving the ribbed post  3292  and the two opposing springs  3282 . Cutouts  3284  are formed on the rear side of the bridge  3244 , and each cutout  3284  intersects the rectangular passage  3245 . Each cutout  3284  is shaped and sized to receive one of the springs  3282 . A vertically extending elongated slot  3285  is also formed on the rear side of the bridge  3244 , and the slot  3285  intersects the passage  3245 . The slot  3285  is sized to accommodate vertical travel of a set screw or pin  3286  that is fixed to the top end of the ribbed post  3292 . The pin  3286 , along with the springs  3282 , constrain vertical translation of the nose rest  3280  within the passage  3245  of the bridge  3244 . The pin  3286  also prevents the nose rest  3280  from becoming detached from the eyewear  3200 . 
     Each longitudinally extending side of the rectangular ribbed post  3292  includes a series of six semi-circular recesses  3287 . The recesses  3287  form an undulating or ribbed surface  3289  along the sides of the post  3292 . Each ribbed surface  3289  is configured to interact with the bulbous end  3288  of a respective spring  3282  to control vertical translation of the nose rest  3280  relative to the bridge  3244  of the eyewear  3200 . 
     The diameter of the bulbous end  3288  is substantially equal to the diameter of each recess  3287 , such that the bulbous end  3288  can be accommodated within each recess  3287 . The bulbous end  3288  is configured to flex during operation, whereas the side  3283  of each spring  3282  may (or may not) be fixed to an interior surface of the bridge  3244 . 
     In operation, a user can manually adjust the vertical position of the nose rest  3280  by either pushing or pulling on the nose rest  3280 . As the user adjusts the position of the nose rest  3280 , the pin  3286  travels within the elongated slot  3285 . At the same time, the bulbous ends  3288  of the springs  3282  flex inwardly and then outwardly as the ribbed surfaces  3289  of the post  3292  travel vertically within the passage  3245 . The post  3292  of the nose rest  3280  can travel between the maximally lowered position of  FIG.  21    and the maximally raised position of  FIGS.  22  and  23   . The post  3292  can be maintained in six different vertical positions corresponding to the number of recesses  3287  on each side of the post  3292 . Adjacent recesses  3287  are separated by 1 mm, for example, such that the total vertical travel of the nose rest  3280  is 5 mm, for example. 
       FIGS.  24 - 25 B  depict an example of eyewear  4200  that utilizes a vertical adjustment coupling  4290  analogous to vertical adjustment coupling  3290 . Vertical adjustment coupling  4290  includes a multi part assembly featuring a ribbed post  4292  extending from nose rest  4280  that interacts with a detent spring  4282  that is positioned within the bridge  4244  of the eyewear  4200 . Interaction between the post  4292  and the spring  4282  controls vertical adjustment of the nose rest  4280 . 
     Bridge  4244  of the eyewear  4200  defines a rectangular passage  4245  for receiving the ribbed post  4292  and the spring  4282 . A vertically extending elongated slot  4285  is formed on the rear side of the bridge  4244 , and the slot  4285  intersects the passage  4245 . The slot  4285  is sized to accommodate vertical travel of a set screw, pin or protrusion  4286  that is fixed to the top end of the ribbed post  4292 . The protrusion  4286 , along with the spring  4282 , constrains vertical translation of the nose rest  4280  within the rectangular passage  4245  of the bridge  4244 . The pin  4286  also prevents the nose rest  4280  from becoming detached from the eyewear  4200 . 
     The rear facing surface of the rectangular ribbed post  4292  includes a series of nine semi-circular recesses  4287 . The recesses  4287  form an undulating or ribbed surface  4289  along the rear surface of the post  4292 . The ribbed surface  4289  is configured to interact with the bulbous semi-circular end  4288  of the spring  4282  to control vertical translation of the nose rest  4280  relative to the bridge  4244  of the eyewear  4200 . The diameter of the bulbous end  4288  is substantially equal to the diameter of each recess  4287 , such that the bulbous end  4288  can be accommodated within each recess  4287 . The top end of the spring  4282  may be fixed to the bridge  4244 , while the bottom end of the spring  4282  defining the bulbous end  4288  is configured to move and flex. 
     In operation, a user can manually adjust the vertical position of the nose rest  4280  by either pushing or pulling on the nose rest  4280 . As the user adjusts the position of the nose rest  4280 , the pin  4286  travels within the elongated slot  4285 . At the same time, the bulbous end  4288  of the spring  4282  flexes inwardly and then outwardly as the ribbed surface  4289  of the post  4292  travels within the passage  4245 . The post  4292  of the nose rest  4280  can travel between the maximally lowered position of  FIG.  25 B  and the maximally raised position of  FIG.  25 A . The post  4292  can be maintained in nine different vertical positions corresponding to the number of recesses  4287  on the post  4292 . Adjacent recesses  4287  are separated by 1 mm, for example, such that the total vertical travel of the nose rest  4280  is 8 mm, for example. 
     It is understood that various modifications can be made to the examples described in this disclosure, and that the subject matter in this disclosure can be implemented in various forms. For example, adjustable couplings according to the present disclosure can be utilized in different types of AR eyewear and for different applications. An adjustable coupling according to the present disclosure can be utilized with a frame containing only a single lens over one of the user&#39;s eyes, for example. Alternatively, the frame can have two separate lenses, where only one of the lenses serves as a waveguide that projects an image toward a user&#39;s eye. 
     Furthermore, it will be understood that eyewear and frame assemblies according to the present disclosure can be supported on the head and face in different ways and need not be limited to eyewear resting on the user&#39;s ears and/or nose. Eyewear and frame assemblies can be supported on the head and face in other ways, while still having one or more adjustable couplings that operate under the same principles described in this disclosure to adjust the vertical and horizontal positions of eye boxes relative to the user&#39;s pupils. 
     The following claims are intended to encompass any and all such modifications and variations within the present disclosure.