Abstract:
A device for aligning the optical axis of a camera is disclosed. The optical alignment device comprises a bracket attaching the device to a frame, the frame incorporating a camera system therein, the camera system having an optical axis projecting substantially horizontally from the camera system, a housing comprising a first part fixed to a first side of the bracket; and a second part comprising a prism refracting the optical axis of the camera system based on a power of the prism and a rotation of the prism with respect to the optical axis and a hinge between the first part and the second part, the hinge rotating the second part with respect to the first part.

Description:
CLAIM OF PRIORITY 
     This application claims, pursuant to 35 USC 120, as a Continuation, priority to and the benefit of the earlier filing date of, that patent application entitled “Adjustable Optical Axis Control, 
     filed on Jan. 17, 2015 and afforded Ser. No. 14/599,487, which claimed pursuant to 35 USC 119, priority to, and the benefit of the earlier filing date of, that patent application entitled “Adjustable Optical Axis Control,” 
     filed on Jul. 24, 2014 and afforded Ser. No. 62/028,692, the contents of which are incorporated by reference, herein. 
     RELATED APPLICATION 
     This application is related to patent application entitled “System for Camera Viewing and Illumination Alignment,” filed on Nov. 22, 2013 and afforded Ser. No. 14/087,322 (now U.S. Pat. No. 9,219,849) and co-pending patent application entitled “System for Camera Viewing and Illumination Alignment,” filed on May 17, 2014 and afforded Ser. No. 14/280,576, the contents each of which is incorporated in their entirety, by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The instant application relates to the field of optics and more particularly to alignment of a camera axis to a desired viewing axis. 
     BACKGROUND OF THE INVENTION 
     GLASS, Google&#39;s head mounted device, represents a type of wearable technology that incorporates a digital camera into a head mounted device, such as a pair of glasses, which allows a user to perform task in a hands-free format. GLASS is a registered Trademark of Google, Inc., 160 Amphitheatre Parkway, Mountain View, Calif. The Google GLASS also has an integrated wide angle camera, which allows the wearer to take both video and images of scenes that are within the optical field of the wide angle camera. Utilizing the features of head mounted display and integrated camera, Google GLASS allows the wearer to capture events in real-time. 
     Generally, the optical axis of the Google GLASS is oriented substantially perpendicular to the mounting of GLASS to the frame. Such a configuration inhibits the optical axis from being independently directed. However, if the wearer is looking in a direction other than substantially perpendicular to the frame, the camera will not record what the wearer is looking at. Rather the camera will record what is substantially perpendicular to the frame. For example, if the user is looking in a downward direction in a task oriented position, e.g., cooking, writing, maintenance work, etc., the camera may or may not record what the wearer is looking at. As a result, users may not be able to orient the optical axis of the camera to intersect a user&#39;s viewing axis at a desired distance from the user. 
     Hence, there is a need in the industry for a method and system for orienting the optical axis of a camera system (e.g., Google GLASS camera) to intersect a user&#39;s viewing axis at a desired distance from the user. 
     SUMMARY OF THE INVENTION 
     A device for orienting an optical axis of a wide angle camera with a user&#39;s viewing axis at a desired distance from the user is disclosed. 
     The device comprises an attachment housing rotatable connected to a second housing. The second housing incorporating a prism assembly aligned with the optical axis of a wide angle camera that provides for the refraction of the optical axis of the wide angle camera. 
     The second housing may have a fixing means to retain the second housing, and the orientation of the prism, to maintain the refracted optical axis of the wide angle camera. 
     A device for aligning the optical axis of a camera is disclosed. The optical alignment device comprises a bracket attaching the device to a frame, the frame incorporating a camera system therein, the camera system having an optical axis projecting substantially horizontally from the camera system, a housing comprising a first part fixed to a first side of the bracket; and a second part comprising a prism refracting the optical axis of the camera system based on a power of the prism and a rotation of the prism with respect to the optical axis and a hinge between the first part and the second part, the hinge rotating the second part with respect to the first part. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       For a better understanding of exemplary embodiments and to show how the same may be carried into effect, reference is made to the accompanying drawings. It is stressed that the particulars shown are by way of example only and for purposes of illustrative discussion of the preferred embodiments of the present disclosure, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. In the accompanying drawings: 
         FIG. 1A  illustrates an exemplary embodiment of a first orientation of an optical axis device control in accordance with the principles of the invention. 
         FIG. 1B  illustrates an exemplary embodiment of a second orientation of an optical axis control device in accordance with the principles of the invention. 
         FIG. 1C  illustrates further details of the second orientation of an optical axis control device in accordance with the principles of the invention. 
         FIG. 2  illustrates a side view of an application of an exemplary device for controlling an orientation of an optical axis of a wide angle camera in accordance with the principles of the invention. 
         FIG. 3  illustrates a top view of an application of an exemplary device for controlling an orientation of an optical axis of a wide angle camera in accordance with the principles of the invention. 
         FIG. 4  illustrates a side view of a second application of an exemplary device for controlling an orientation of an optical axis of a wide angle camera in accordance with the principles of the invention. 
         FIG. 5  illustrates a top view of the second application of the exemplary device for controlling an orientation of an optical axis of a wide angle camera in accordance with the principles of the invention. 
         FIGS. 6A-6D  illustrate perspective views of the optical axis orientation control device in accordance with the principles of the invention. 
         FIG. 7  illustrates a cross-section view of the optical axis orientation control device in accordance with the principles of the invention. 
         FIGS. 8A-8B  illustrates perspective views of an optical device in accordance with the principles of the invention. 
         FIGS. 9A-9B  illustrate graphs of an orientation of an optical device in accordance with the principles of the invention versus working distance. 
         FIG. 10  illustrates a table of orientation settings of an optical device in accordance with the principles of the invention versus working distance. 
     
    
    
     It is to be understood that the figures and descriptions of the present invention described herein have been simplified to illustrate the elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity many other elements. However, because these omitted elements are well-known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such element is not provided herein. The disclosure herein is directed to also variations and modifications known to those skilled in the art. 
     DETAILED DESCRIPTION 
       FIG. 1A  illustrates an exemplary optical axis control device  100  in accordance with the principles of the invention. In this illustrated example, control device  100  is attached to a wide angle lens camera system  110 . In one aspect of the invention, the wide angle lens camera system  110  may be the same or similar to that of the commonly referred to Google GLASS, that is currently available. In accordance with the principles of the invention, the focal point of camera system  110  is altered from the optical axis  130  shown to lie along the angle of refraction (e.g.,  140 ,  140 ′) of prism  105 , as described in further detail herein. 
     Although the present invention is described with regard to the Google GLASS device, it would be appreciated that the present invention may be applicable to any head mounted wide angle camera system. Furthermore, it would be recognized that the wide angle camera system  110  may be incorporated into a headset that attaches to a user in a manner similar to that of eye-glasses and/or headbands, wherein the optical control device  100  may be incorporated into, or attached to, the eye-glasses and/or headband. 
     As illustrated, the optical axis  130  of the wide angle camera  115  in the wide angle camera system  110  (e.g., Google GLASS) is oriented substantially perpendicular to camera  115 . As would be appreciated the optical axis  130  is contained in a plane that is substantially perpendicular in the plane of the paper on which the drawing is shown. 
     In accordance with the principles of the invention, an optical lens or prism  105  incorporated into control device  100  alters the orientation of the optical axis  130  of the wide angle camera  115  to lie along the downward (with respect to the plane containing optical axis  130 ) axis  140 . Axis  140  in this altered or deflected state represents an effective optical axis of the camera  115 . 
     Also illustrated is rotary joint  160 , which allows prism  105  to be rotated, around the optical axis  130  of camera  115 , to change the direction of axis  140  in a substantially circular direction  170 . Rotary joint  160  is used to radial change the refracted axis of prism  105  about optical axis  130  such that the optical axis  130  of the wide angle camera  115  may be changed to one of a plurality of positions along a conical section as represented by axis  140 . 
     Optical control device  100  further includes a frame  117  and a tab  118 , which together attach optical control device  100  to camera system  110  (e.g. via a C-clamp-type bracket configuration). Screw  119 , when tightened, retains pressure between tab  118  and frame  117  such that device  100  remains optically aligned with optical axis  130  of camera  115 . Alternatively, frame  117  may include an extension tab  111 , which attaches to a back end of camera system  110  or frame. In one aspect of the invention, tab  111  may be fixed such that device  100  may be snapped fitted onto camera system  110 . In another aspect of the invention, tab  111  may be rotatable such that tab  111  may, in one state engage the back of camera system  110  and in another state be rotated away from the back of camera system  110 . In a preferred embodiment, optical control device  100  is a removable device. Alternatively, optical control device  100  may be permanently mounted to camera system  110 . 
       FIG. 1B  illustrates a second aspect of the control device  100  shown in  FIG. 1A , wherein the orientation of prism  105  is changed by the rotation of the orientation of prism  105  by rotary joint  160 . In this illustrated aspect, the orientation of the optical axis  130  of the wide angle camera  115  is altered so as to lie along upward (with respect to the plane containing the optical axis  130 ) axis  140 ′. 
     In accordance with the principles of the invention, the effective optical axis  130  of camera  115  is directed along the edge of the conical shape as represented by axis  140  and axis  140 ′. By rotating prism  105  radially through 360 degrees (line  170 ) the refracted line of sight of the prism will sweep around a circle (line  170 ) forming a conical shape around the original line of sight (i.e., optical axis  130  of camera  115 ). For example, prism  105  may be rotated such that the effective optical axis  140  ( 140 ′) may lie within the plane containing the optical axis  130 . Similarly, the prism  105  may be rotated to achieve any angle between the axis  140  extending below the horizontal plane containing the optical axis  130  ( FIG. 1A ) and the axis  140 ′ extending above the horizontal plane containing the optical axis  130  ( FIG. 1B ) along the conical shape formed by rotation of prism  105  along line  170 . 
       FIG. 1C  illustrates, similar to  FIG. 1B , a second aspect of the embodiment of the invention. In this illustrated example, the field of view  192  of camera  115 , which is centered on optical axis  130 , is altered so that an altered field of view  194  of camera  115  is centered on effective optical axis  140 ′. As would be appreciated, the field of view of camera  115  is determined based on the characteristics of the camera  115  and corresponding lens system. Refraction of optical axis  130  by prism  105  along the conical shape, represented by axis  140  and axis  140 ′, retains substantially the original camera field of view. 
       FIG. 2  illustrates a side view of an application of the optical axis control device  100  attached to a wide angle camera system  110 , such as Google GLASS, wherein the optical axis  130  of the wide angle camera  115  (hidden by optical axis control device  100 ) is altered or refracted to lie along the downward (with respect to the horizontal plane containing the optical axis  130 ) axis  140 . In addition, the angle to which the optical axis of camera  115  is altered is such that the axis  140  intersects a task oriented point  220 . Task oriented point  220  represents a point (or area) of convergence of the altered optical axis  140  of camera  115  and an optical line of vision  212  of a user. 
     As would be recognized, and discussed in further detail, herein, the angle of refraction (i.e., alteration or deflection) of the optical axis  130  of camera  115  may be dependent upon the power of prism  105 . For example, prisms having a high power cause greater alteration in the optical axis  130  that prisms having lower power. 
     In accordance with the principles of the invention, rotating prism  105  by joint  160 , and deflecting (refracting) the optical axis  130  of camera  115  along effective optical axis  140  so as the viewing axis of camera  115  is directed to a point (e.g., task oriented point  220 ) at which the user is viewing, the field of view  192  of camera  115  is able to capture (either images or video) what the user is viewing (e.g., field of view  194 ) without the user adjusting his/her position to move camera  115  into a suitable position. 
     Although camera  115  is offset from the user&#39;s eyes, it would be recognized that, while the offset causes some degree of parallax, between the user&#39;s optical line of sight and the effective camera axis  140 , the effect of parallax is diminished as the distance of task point  220  from camera  115  increases. Similarly, the effect of parallax between the effective optical axis of camera  140  and the user&#39;s line of sight may be diminished and compensated for using known methods. 
       FIG. 3  illustrates a top view of the application of the optical axis control device  100  shown in  FIG. 2 . In this illustrated example, optical control device  100  alters the orientation of prism  105  such that the effective optical axis  140  of camera  115  is directed toward task oriented point  220 . Task point  220  is determined based on the user&#39;s eye position, which may be represented as the intersection of the viewing axis  330  of the user&#39;s right eye and the viewing axis  330 ′ of the user&#39;s left eye. Thus, as the user&#39;s eyes change position the task point  220  changes and by appropriate orientation of prism  105 , the effective optical axis  140  of camera  115  may coincide with the changed position of task point  220 . 
     By maintaining the orientation of prism  105  such that the effective optical axis  140  of camera  115  is maintained at task point  220 , camera  115  captures and/or records images at task oriented point  220  that are being viewed by the user. 
     Thus, in accordance with the principles of the invention, images of the tasks being performed by a user at the task point  220  may be captured and/or recorded without the user adjusting the camera&#39;s position in order to have the effective optical axis  140  of camera  115  to coincide with, or converge onto, task point  220 . 
     As would be appreciated, the power and/or orientation of prism  105  may be designed for different distances of the task oriented point  220  from the user. For example, angle  215 , which is measured between the refracted image axis  140  of prism  105  and the plane of surface  216  of prism  105 , may be altered based on the power prism  105 . In one aspect of the invention, by varying the angle  215  (thus, the angle of refracted image axis  140 ), the distance of task oriented point  220  from the user may be varied toward or away from the user. Thus, different prism powers may be used to accommodate different distances of task oriented point  220 . 
     Alternatively, the orientation of prism  105  with respect to the optical axis  130  of camera  115  (see  FIG. 1A ) may be adjusted to allow, for a same power prism, task oriented points  220  to lie at different distances from the user, as will be further discussed. 
       FIG. 4  illustrates another exemplary application of the optical axis control device in accordance with the principles of the invention. 
     In this illustrative example, the wide angle camera  115  (not shown) incorporated into camera system (e.g., Google Glass)  110  that is incorporated into a surgical or dental headset  310 . Surgical or dental head set  310  includes lens  315  into which telescopic lens  320  are incorporated. Typically, telescopic lens  320  may be oriented an any angle (downward) with respect to a horizontal plane (not shown), passing through the ends of telescopic lens  320 , that is substantially parallel to the horizontal plane of optical axis  130 . While telescopic lens  320  may be oriented at any known downward angle, for the purposes of describing the invention herein, a downward angle of 25 degrees is selected as a typical downward angle. 
     Furthermore, as  FIG. 4  illustrates a side view of the surgical or dental headset  310 , it would be appreciated that a second lens and telescopic lens  320  is not shown. The pair of telescopic lens  320  are also angularly oriented such that the line of sight of the telescopic lens  320  converge at task oriented point  220 . 
     Telescopic lens  320  enables a surgeon or dentist to view an enlarged image of a desired area (e.g., task point  220 ). In many cases, a surgeon, for example, will operate where his working area is well below the level of his eyes and the surgeon will not necessarily tilt their head down in order to see the working area. In this situation, the surgeon may have a more horizontal head angle (e.g., in a plane parallel to the horizontal plane containing optical axis  130 ) and will depend on changing his eye position in order to look down a pair of angled telescopic lens  320 , along viewing axis  330 , to effectively view the area being operated on (e.g., task point  220 ). Since the surgeon&#39;s head is oriented generally horizontally, the wide angle camera  115  is not positioned to capture the operating area (task point  220 ) as the optical axis  130  is oriented substantially perpendicular to the headset  310  in the plane containing optical axis  130 . 
     In accordance with the principles of the invention, the surgeon or dentist may orient prism  105  in optical control device  100  such that the optical axis  130  of camera  115  (not shown) is substantially coincident with effective optical axis  140  such that the field of view  194  of camera  115  is convergent upon the operating area (i.e., task oriented point  220 ). In this manner, a surgeon or dentist may record a task that the surgeon or dentist is performing even if the surgeon lifts his/her eye position during the operation or surgery. Furthermore, if the surgeon lifts his/her head and changes the effective optical axis  140  of camera  115 , the correct orientation of the effective optical axis  140  may be reacquired when the surgeon returns their head/eyes to the task oriented point  220 . 
     As discussed previously, a parallax effect between the effective optical axis  140  and viewing axis  330  is reduced as a distance to the task point  220  increases. Similarly, at closer ranges any parallax may be minimized by appropriate compensation. Alternatively, the effect of parallax may be minimal with the utilization of a camera  115  with a wide angle field of view. 
       FIG. 5  illustrates a top view of the application of the optical axis control device  100  shown in  FIG. 4 . 
     In this illustrated example, the task oriented point  220  is determined by the intersection of the viewing axis  330  of the right eye and the viewing axis  330 ′ of the left eye through telescopic lens  320  and  320 ′, respectively. Prism  105  is rotated by joint  160  (not shown), as previously discussed, such that the optical axis  130  of camera  115  (not shown) is coincident with axis  140 , such that the effective optical axis of camera  115  is directed toward and substantially intersects task point  220 . As previously discussed, in one aspect of the invention, at least one of the power and orientation of prism  105  determines the degree of refraction and, thus, the effective optical axis  140 . In one aspect of the invention, a same task oriented point  220  may be achieved using different angles of rotation and powers of prism  105 . Similarly, the distance of the task oriented point  220  from the user may be varied based on the use of different prisms with different powers and different angles of rotation. 
       FIG. 6A  illustrates a right side view of the optical axis control device  100 , similar to that shown in  FIG. 1A . Device  100  includes frame  117  used to attach device  100  to a head set including a camera  115  (e.g., Google Glass), as previously discussed. Frame  117  further includes a first housing  620  connected to second housing  610 . Prism  105  is incorporated into second housing  610 . Prism  105 , as is generally known, is an optical clear glass or plastic lens that reflects light passing through it. As shown prism  105  may have a right angular configuration, wherein the base leg is attached to second housing  610  and the hypotenuse leg projects from second housing  610 . The power of prism  105  is determined by the desired angle of the task orient point  220  in relation to the line of sight of the user and the position of the camera image axis. 
     Second housing  610  rotates with respect first housing  620  through joint  160  and changes the orientation of optical axis of camera  115  passing through prism  105  (see  FIG. 1A ). As previously discussed, frame  117  in conjunction with tab  118  (or tab  111 ) retains device  100  onto wide angle lens camera system  110 . Camera  115 , may itself be attached to, or incorporated within, a frame of an eyeglass or headband. Optical control device  100  is constructed such that the optical axis  130  of camera  115  is aligned, through an opening in the first housing, with prism  105 . 
       FIG. 6B  illustrates a front view of the optical axis control device  100 , in accordance with the principles of the invention, showing camera system  110  and second housing  610 , which includes prism  105 . Further illustrated, through prism  105 , is lens opening  611  in second housing  610 . Lens opening  611  in second housing  610  coincides with a similar lens opening  612  in first housing  620 . Lens openings  611  and  612  further coincides with, and are optically aligned to, the optical axis  130  (not shown) of camera  115 . 
       FIG. 6C  illustrates a left side view of the optical axis control device  100 , which is similar to the right side view shown in  FIG. 6A . In this exemplary embodiment, device  100  is shown attached to camera system  110  through a pressure asserted between tab  118  and frame  117  by screw  119 . 
     As further shown an outer rim of second housing  610  may be knurled or serrated to provide a roughen surface to rotate second housing  610  with respect to first housing  620 . 
       FIG. 6D  illustrates an exploded perspective view of control device  100  showing frame  117 , first housing  620  and second housings  610 , which includes prism  105 . Also shown is rotary joint  160  positioned on second housing  610  and engaging an interior surface of first housing  620 . As shown a groove  650  may be included in first housing  610 , which is used to guide rotation of second housing  610 . 
     Groove  650  of rotary joint  160  may engage a tab or a raised track (not shown) in first housing  620 , through which first housing rotates with respect to first housing  620 . The engagement of groove  650  of rotary joint  160  with tab or a raised track (not shown) in first housing  620  enables second housing  610  to rotate about an axis substantially perpendicular to the first housing  620 . 
     In accordance with the principles of the invention, second housing  610  may, thus, rotate substantially perpendicular to optical axis  130  of camera  115 , as previously described. 
     Although it has been shown that the rotary joint  160  is positioned on second housing  610 , it would also be appreciated that the rotary joint  160  may be positioned on first housing  620  without altering the scope of the invention. For example, first housing  620  may include an internal track or groove (not shown) and joint  160 , located on second housing  610 , may include a raised tab or raised track (not shown) that engages the not shown internal track or groove within first housing  620 . 
     Further illustrated is screw  119  used in conjunction with tab  118  to retain device  100  in a fixed relationship with the optical axis  130  of camera  115  of wide angle lens camera system  110  (e.g., Google Glass). 
     Also illustrated is tab stop  651  in groove  650 . Tab stop  651  limits the rotation of second housing  610  with respect to first housing  620 . Utilizing tab stop  651 , for example, limits the rotation of second housing  610  such that the refracted axis  140  of prism  105  may be limited to angles that point inward and toward task point  220  (not shown). 
     Although tab stop  651  allows for limited rotation of second housing  610 , it would be recognized that groove  650  may be fabricated without tab stop  651  and thus, a full 360 degree rotation of second housing with respect to first housing  620  may be achieved. Similarly if two stops  651  are incorporated into groove  660 , then rotation of second housing  610  with respect of first housing  620  is limited between the first and second tab stops  651 . 
       FIG. 7  illustrates a cross-sectional view of the optical axis control device  100  retained on wide angle camera system  110 . In this illustrative example, optical control device  100  is retained on wide angle camera system  110  between frame  117  and tab  118  by engagement of screw  119  (as previously described). Further illustrated is first housing  620  and second housing  610 , including prism  105 . Within first housing  620  is a tab or raised track  710 . Tab or raised track  710  engages groove  650  in second housing  610 , such that second housing  610  may rotate with respect to first housing  620 . Rotation of second housing  610  enables prism  105  to rotate with respect to optical axis  130  of camera  115 , as previously discussed. 
     Although  FIG. 7  illustrates an example of rotary joint  160  including tab or raised track  710  in first housing  620  and groove  650  in second housing  610 , it would be appreciated that in an alternative embodiment, tab or raised track  710  may be formed in second housing  610  and groove  650  may be formed in first housing  620  without altering the scope of the invention claimed. Similarly the limiting tab  651  may be incorporated into groove  650 , which in this alternative embodiment, is contained in first housing  620 . 
       FIG. 8A  illustrates a perspective view of an optical control device  100  and camera system  110  attached to an eyeglass assembly  810  including telescopic lens  320 ,  320 ′, associated with the right and left eye, respectively. Also, shown is task point  220  at a distance of thirty (30) inches from the eyeglass assembly  810 . 
     For purposes of describing the inventive concept of the present invention, in this illustrative embodiment, prism  105  is selected as a 15 degree diopter prism. As would be recognized in the art, a diopter represents a measure of the deflection of light passing through a prism equal to a deflection of 1 centimeter at a distance of 1 meter. It would be recognized that prisms of other powers (i.e., diopter) may be selected without altering the scope of the invention. 
     As shown, with a 15 degree diopter prism, in order to focus the effective optical axis  140  at or substantially near task point  220 , with an orientation of telescopic lens  320  at a 25 degree down angle (from the horizontal plane parallel to the horizontal plane containing the optical axis  130 ), prism  105  is rotated at an angle of 8.62 degree above the horizontal plane containing the optical axis  130  so as to orient the optical axis  130  of camera  115  at a down angle of 27.7 degrees. Positioning prism  105  at the illustrated down angle orients the optical axis  130  of camera  115  along the effective optical axis  140  so as to focus the field of view of camera  115  on task point  220  (formed by the intersection of the viewing lines  330 ,  330 ′).  FIG. 8B  illustrates a perspective view of the orientation of optical device  100  similar to that shown in  FIG. 8A , wherein the task point  220  is selected to be nine (9) inches from the eyeglass  810 . In this case, the 15 degree diopter prism  105  is oriented at a down angle of 34.52 degrees by rotating prism  105  by 22.5 degrees from the horizontal plane containing the optical axis  130  in order to orient the optical axis  130  of camera  115  along effective optical axis  140 . 
       FIGS. 9A and 9B  illustrate graphs of down angle and rotational angle, respectively, as a function of distance, with a 15 degree Diopter prism.  FIG. 9A  illustrates, for the configuration shown in  FIGS. 8A and 8B , the down angle required (i.e., the effective optical axis  140 ) to focus camera  115  onto task point  220  varies between 42 and 28 degrees.  FIG. 9B  illustrates that the rotational angle (from the horizontal plane containing the optical axis  130 ) to achieve the required distance varies between 30 and 9 degrees. 
     Although  FIGS. 9A and 9B  illustrate the operational conditions for a particular configuration (i.e., 15 degree diopter prism and telescopic lens at 25 degrees downward angle) it would be appreciated, that either one or both of the prism power and telescopic lens orientation (or no telescopic lens at all) may be altered without altering the scope of the invention. For example, the prism power may be selected to be in a range of 5-25 degree diopter. A specific power may be determined based on the downward angle of the telescopic lens. Similarly, the prism power and the downward angle of the telescopic lens may be determined based on a desired task point distance. Such different configurations have been contemplated and are considered to be within the scope of the invention. 
       FIG. 10  illustrates a chart of the combination of working distance (task point  220 ) and the rotational angle of prism  105  to achieve a down angle necessary to deflect the optical axis  130  of camera  115  along effective optical axis  140 .  FIG. 10  illustrates rotational angles for the optical control device  100  when incorporated into an assembly having downward orientation (i.e., drill angle) of 25 degrees and a prism power of 15 degree Diopter. It would be within the knowledge of those skilled in the art to formulate combinations of working distance and rotational angles using different prism power to achieve different down angles. The use of different downward orientations and/or prism powers is considered to be within the scope of the invention claimed herein. 
     Returning to  FIGS. 1A and 1B ,  FIGS. 1A and 1B  illustrate a conventional configuration of a flat face of prism  105  being substantially perpendicular to the optical axis  130  of camera  115  (hidden by optical axis control device  100 ), it would be appreciated that the flat face of prism  105  may be oriented offset from a perpendicular position such that the angle of refraction caused by prism  105  may be different than when prism  105  is oriented as shown in  FIGS. 1A and 1B . 
     Thus, the orientation of prism within second housing  610  as being parallel to or offset from second housing  610  is also considered to be within the scope of invention. 
     Although not shown it would be appreciated that a locking mechanism may be utilized to lock or retain the rotational angle of prism  105  at a desired angle. For example, a screw (not shown) may be screwed through the first and second housings to in order to retain the positional relationship between the first and second housings. 
     The invention has been described with reference to specific embodiments. One of ordinary skill in the art, however, appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims. Accordingly, the specification is to be regarded in an illustrative manner, rather than with a restrictive view, and all such modifications are intended to be included within the scope of the invention. 
     Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. The benefits, advantages, and solutions to problems, and any element(s) that may cause any benefits, advantages, or solutions to occur or become more pronounced, are not to be construed as a critical, required, or an essential feature or element of any or all of the claims. 
     As used herein, the terms “comprises”, “comprising”, “includes”, “including”, “has”, “having”, or any other variation thereof, are intended to cover non-exclusive inclusions. For example, a process, method, article or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, unless expressly stated to the contrary, the term “of’ refers to an inclusive “or” and not to an exclusive “or”. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); and both A and B are true (or present). 
     The terms “a” or “an” as used herein are to describe elements and components of the invention. This is done for convenience to the reader and to provide a general sense of the invention. The use of these terms in the description herein should be read and understood to include one or at least one. In addition, the singular also includes the plural unless indicated to the contrary. For example, reference to a composition containing “a compound” includes one or more compounds. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     All numeric values are herein assumed to be modified by the term “about,” whether or not explicitly indicated. The term “about” generally refers to a range of numbers that one of skill in the art would consider equivalent to the recited value (i.e., having the same function or result). In any instances, the terms “about” may include numbers that are rounded (or lowered) to the nearest significant figure. 
     It is expressly intended that all combinations of those elements that perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Substitutions of elements from one described embodiment to another are also fully intended and contemplated.