Abstract:
A method and apparatus involve: admitting through objective optics of an optical sight a beam of radiation representing a scene; generating two different images of the scene; supplying the images to respective portions of a field of view at a viewing section; and superimposing a respective reticle onto each image. According to a different aspect a method and apparatus involve: causing two beams of radiation within an optical sight that represent different images of a scene to approach a reflective section in different directions, the reflective section causing a portion of each beam to reach a respective portion of a field of view at a viewing section; and superimposing a respective reticle onto each beam portion.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates in general to optical sights and, more particularly, to optical sights that provide a split field of view. 
       BACKGROUND 
       [0002]    Optical sights or scopes are used for a variety of purposes, one of which is to help a person accurately aim a firearm such as a rifle or a target pistol. The optical sight is typically mounted on the barrel of the firearm, and the person uses the sight to view the intended target in association with a reticle, often with a degree of magnification. Some sights have a tumbler that can be moved between two different positions in order to change the degree of magnification. That is, when the tumbler is in one position, the user sees the intended target with one degree of magnification, and when the tumbler is in the other position, the person sees the same target with a different degree of magnification. 
         [0003]    Still another approach is to omit the tumbler and provide a split field of view, where the person simultaneously sees the same target with different degrees of magnification. Although pre-existing optical sights with split fields have been generally adequate for their intended purposes, they have not been satisfactory in all respects. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    A better understanding of the present invention will be realized from the detailed description that follows, taken in conjunction with the accompanying drawings, in which: 
           [0005]      FIG. 1  is a diagrammatic view showing an apparatus that is an optical sight that embodies aspects of the invention, and through which a remote scene can be viewed by the eye of a user. 
           [0006]      FIG. 2  is a diagrammatic view showing an example of a split field of view that a person would see when using the sight of  FIG. 1 . 
           [0007]      FIG. 3  is a diagrammatic view that is similar to  FIG. 1 , but shows an optical sight that is an alternative embodiment of the optical sight of  FIG. 1 . 
           [0008]      FIG. 4  is a diagrammatic view showing a portion of an optical sight that is an alternative embodiment of a corresponding portion of the optical sight of  FIG. 3 . 
           [0009]      FIG. 5  is a diagrammatic view showing a portion of an optical sight that is a further alternative embodiment of a corresponding portion of the optical sight of  FIG. 3 . 
       
    
    
     DETAILED DESCRIPTION 
       [0010]      FIG. 1  is a diagrammatic view showing an apparatus that is an optical sight  10  that embodies aspects of the invention, and through which a remote scene  11  can be viewed by the eye  12  of a user. In the disclosed embodiment, the sight  10  can be removably mounted on a not-illustrated weapon such as a rifle or target pistol, but the invention is not limited to a weapon sight. 
         [0011]      FIG. 2  is a diagrammatic view showing an example of a split field of view (FOV) that the eye  12  of a user ( FIG. 1 ) would see when using the sight  10 . In more detail, a circular FOV  16  shows an image of part of the scene  11  ( FIG. 1 ), including a target  17 . The sight  10  superimposes a reticle  18  on this image of the scene. In the disclosed embodiment, the reticle  18  is a crosshairs-type reticle, but it could alternatively have any other suitable configuration. For the sake of discussion, it is assumed that the person using the sight has centered the reticle  18  on the head of the target  17 , as shown in  FIG. 2 . In the disclosed embodiment, this FOV is provided with a magnification of lx, but it would alternatively be possible to use some other magnification. 
         [0012]    A second circular FOV  21  is inserted in the lower portion of the larger FOV  16 . This smaller FOV  21  provides a magnified view of a portion of the image in the larger FOV  16  that is in the region around the center of reticle  18 . The sight  10  superimposes a reticle  22  on this magnified image in FOV  21 . In the disclosed embodiment, the reticle  22  is a crosshairs-type reticle, but it could alternatively have any other suitable configuration. The reticle  22  in the FOV  21  is centered on the same portion of the target  17  as the reticle  18  in the FOV  16 . In the disclosed embodiment, the smaller FOV  21  provides a magnification of 4× in relation to the FOV  16 , but it would alternatively be possible to use some other suitable magnification. 
         [0013]    Referring again to  FIG. 1 , the optical sight  10  includes an objective lens  31  through which a beam of radiation from the scene  11  enters the optical sight. Although the sight  10  of  FIG. 1  has a single objective lens  31 , this could alternatively be a doublet, or some other suitable multi-lens configuration. The sight  10  also includes a beam splitter  33 , but this could alternatively be some other suitable optical component, such as a splitting mirror. In the disclosed embodiment, the beam splitter  33  is oriented an angle of approximately 45° to the optical axis  32  of a beam of radiation that enters through the lens  31  and then travels to the beam splitter  33 . At the beam splitter  33 , a portion of this beam passes through the beam splitter and continues to travel rightwardly in  FIG. 1 , while another portion of the beam is reflected by the beam splitter and then travels downwardly. The portion of the beam that passes through the beam splitter  33  travels to and passes through a magnification control lens  36 . The lens  36  is positioned so that it is slightly eccentric to the optical axis  32 . Although the sight  10  of  FIG. 1  uses a single lens at  36 , this could alternatively be a doublet, or some other suitable multi-lens configuration. 
         [0014]    The optical sight  10  includes a combining element  38  that is oriented at an angle of approximately 45° with respect to the optical axis  32 , and with respect to the path of travel of radiation that has passed through the lens  36 . The combining element  38  includes a glass plate  41  that is made from a material transmissive to visible radiation, and that has a reflective coating  43  of a known type provided on a side thereof remote from the lens  36 . The reflective coating  43  has an opening  46  extending therethrough at a location offset from the optical axis  32 . In the disclosed embodiment, the opening  46  has a shape that is approximately an oval, so that when this opening is viewed in a direction parallel to the optical axis  32 , the opening  46  appears to be circular. Two thin perpendicular lines of an opaque material (not visible in  FIG. 1 ) are formed on the same side of the glass plate  41  as the coating  43 , and are centered within the opening  46 . These two lines generate the reticle  22  ( FIG. 2 ). Two additional thin perpendicular lines of the opaque material (not visible in  FIG. 1 ) are provided on the reflective coating  43  at a location offset from the opening  46 , and generate the reticle  18  ( FIG. 2 ). 
         [0015]    In the disclosed embodiment, an anti-reflective (AR) coating of a known type (not visible in  FIG. 1 ) is provided on a side of the glass plate  41  opposite from the reflective coating  43 . A further AR coating of a known type is provided on the same side of the glass plate  41  as the reflective coating  43 , but only within the circular opening  46 . As to radiation that passes through the objective lens  31 , beam splitter  33 , and magnifying lens  36 , a portion of this radiation passes through the glass plate  41 , impinges on the inner side of the reflective coating  43 , is reflected, and then travels upwardly and is lost. The remainder of the radiation from the lens  36  passes through the glass plate  41 , and then through the oval opening  46  in the plate  41 . This radiation then passes through an ocular lens  51  of the sight  10  that serves as a viewing section, and continues on its way to the eye  12  of the user. The eye  12  sees this radiation as the magnified FOV  21  ( FIG. 2 ). Although the sight  10  of  FIG. 1  uses a single lens at  51 , this could alternatively be a doublet, or some other suitable multi-lens configuration. 
         [0016]    The sight  10  further includes a fold mirror  56 , a magnification control lens  58 , and a fold mirror  61 . Although the sight  10  of  FIG. 1  uses a single lens at  58 , this could alternatively be a doublet, or some other suitable multi-lens configuration. The portion of the incoming radiation that is reflected by the beam splitter  33  travels downwardly to and is reflected by the fold mirror  56 , travels rightwardly to and passes through the lens  58 , and then travels to and is reflected by the fold mirror  61 . This radiation then travels upwardly from the fold mirror  61  to the combining element  38 . A portion of this radiation impinges on the combining element  38  in the region of the opening  46  through the coating  43 . This portion of the radiation travels upwardly through the opening  46  and is effectively lost. The remainder of the radiation from the mirror  61  impinges on and is reflected by the reflective coating  43 , and simultaneously has the reticle  18  superimposed thereon by the two opaque lines on the coating  43 . This radiation, including the reticle  18 , then travels rightwardly through the ocular lens  51  to the eye  12  of the user, where it appears as the larger FOV  16  ( FIG. 2 ). The optics of the sight  10  are configured so that the lens  31 , lens  58  and lens  51  collectively provide an effective magnification of 1×, and so that the lens  31 , lens  36  and lens  51  collectively provide an effective magnification of 4×. The beam splitter  33  can be configured to have a splitting ratio that provides a desired relationship in the relative brightnesses of the 1× and 4× images. 
         [0017]    The sight  10  of  FIG. 1  has fixed-focus optics with no moving parts. The 1× path (through lens  58 ) is configured to be focused at approximately 30-50 yards, and the 4× path (through lens  36 ) is configured to be focused at approximately 120 yards. However, one or both of the 1× and 4× paths could be configured to be focused at some other distance. As another alternative, the sight  10  could be provided with one or more lenses or other optical parts that are movably supported and that provide a zoom effect for both FOVs. 
         [0018]      FIG. 3  is a diagrammatic view that is similar to  FIG. 1 , but shows an optical sight  110  that is an alternative embodiment of the optical sight  10  of  FIG. 1 . The sight  110  of  FIG. 3  generates effectively the same split FOV ( FIG. 2 ) as the sight  10  of  FIG. 1 . Components in  FIG. 3  that are identical to or equivalent to components in  FIG. 1  are identified with the same reference numerals in both figures, and are not discussed again in detail. The following discussion focuses on the differences between  FIGS. 1 and 3 . 
         [0019]    The combining element  38  of  FIG. 1  is replaced in  FIG. 3  with a combining element  138 . The combining element  138  includes a glass plate  141  that is made of a material transmissive to visible radiation, and that has on a side opposite from the beam splitter  33  a small reflective coating  143  with approximately an oval shape. When the oval-shaped reflective coating  143  is viewed in a direction parallel to the optical axis  32 , it appears to be circular. Although not visible in  FIG. 3 , two perpendicular lines of opaque material are provided on the coating  143 , and intersect at the center of the coating  143 . These two lines generate the reticle  22  of  FIG. 2 . Also, two further perpendicular lines of opaque material are provided on the side of the glass plate  141  opposite from the beam splitter  33 , at a location offset downwardly from the coating  143 . These two lines generate the reticle  18  of  FIG. 2 . The glass plate  141  has an AR coating on each side thereof, except where the reflective coating  143  is provided. 
         [0020]    The sight  110  includes, to the right of the combining element  138 , a lens  167  and an erecting prism  169  of a known type. Although the sight  110  of  FIG. 3  uses a single lens at  167 , this could alternatively be a doublet, or some other suitable multi-lens configuration. The erecting prism  169  may actually be multiple separate prisms that are physically coupled to each other, but for simplicity and clarity, the prism  169  is treated here as a single component. The erecting prism  169  has five surfaces  171 ,  172 ,  173 ,  174  and  175  that each have thereon a reflective coating that is not separately illustrated. In  FIG. 3 , as discussed above, the opaque perpendicular lines that generate the two reticles  18  and  22  ( FIG. 2 ) are provided on a surface of the glass plate  141 . However, they could alternatively be provided at some other suitable location. By way of example and not limitation, the opaque lines could be provided on either the surface  171  or the surface  175  of the erecting prism  169 , between the prism surface and the reflective coating thereon. 
         [0021]    A beam of radiation from the scene  11  enters the optical sight  110  through the objective lens  31 . This beam of radiation travels to the beam splitter  33 , where one portion passes through the beam splitter, and another portion is reflected by the beam splitter and travels downwardly. The radiation that passes through the beam splitter  33  travels to and passes through the lens  58 , and then travels to the combining element  138 . A portion of this radiation will pass through the glass plate  141 , will impinge on the rear side of the oval reflective coating  143 , will be reflected and travel upwardly, and will effectively be lost. The remainder of the radiation from the lens  58  will pass through the glass plate  141 , and the reticle  18  ( FIG. 2 ) will be superimposed on this radiation. This radiation will then continue traveling rightwardly in a generally horizontal direction in  FIG. 3 , and will pass through the lens  167  and then enter the erecting prism  169 . This radiation will be successively reflected at each of the five surfaces  171 - 175  in the erecting prism  169 , and will then exit the erecting prism and travel through the ocular lens  51  to the eye  12  of the user. This radiation serves as the larger 1× FOV  16  in  FIG. 2 . 
         [0022]    The radiation reflected by the beam splitter  33  travels vertically downwardly in  FIG. 3  to the fold mirror  56 , where it is reflected and then travels approximately horizontally to the fold mirror  61 . At the fold mirror  61 , this radiation is reflected again and travels vertically upwardly in  FIG. 3  to the combining element  138 . A portion of this radiation will impinge on the combining element  138  at locations spaced from the reflecting surface  143 , will pass through the glass plate  141 , will continue traveling upwardly, and will effectively be lost. In contrast, the portion of this radiation that impinges on the oval reflective coating  143  will be reflected and simultaneously have the reticle  22  ( FIG. 2 ) superimposed thereon. This radiation will then travel rightwardly in  FIG. 3  through the lens  167 , through the erecting prism  169 , and through the ocular lens  51  to the eye  12  of the user. This radiation serves as the smaller 4× FOV  21  in  FIG. 2 . 
         [0023]      FIG. 4  is a diagrammatic view showing a portion  210  of an optical sight, this portion being an alternative embodiment of a corresponding portion of the optical sight  110  of  FIG. 3 . The basic difference is that, in the sight of  FIG. 4 , an aperture stop  281  with a circular opening  282  therethrough has been added between the beam splitter  33  and the lens  58 . The aperture stop  281  allows the eye  12  of a user ( FIG. 3 ) to be spaced a short distance from the optical sight, but still see the full image of the larger FOV  16  ( FIG. 2 ). The operation of the embodiment of  FIG. 4  is generally similar to that of the embodiment of  FIG. 3 , and is therefore not described again here in detail. 
         [0024]      FIG. 5  is a diagrammatic view showing a portion  310  of an optical sight that is a further alternative embodiment of a corresponding portion of the optical sight  110  of  FIG. 3 . Only the differences are discussed here. In particular, in  FIG. 5 , the positions of the fold mirrors  56  and  61  have been adjusted slightly in comparison to  FIG. 3 . An L-shaped baffle  386  has been added, and is made from a material that is opaque and absorptive to visible radiation. The baffle  386  has a vertical leg  387  with its upper end adjacent the lower end of the beam splitter  33 . The baffle  386  also has a horizontal leg  388  that extends from the lower end of leg  387  to a location above the fold mirror  61 . The leg  388  has a circular opening  389  extending therethrough near an outer end thereof, at a location above the fold mirror  61 . The operation of the embodiment of  FIG. 5  is generally similar to that of the embodiments of  FIGS. 3 and 4 , and is therefore not described again here in detail. 
         [0025]    Although some selected embodiments have been illustrated and described in detail, it should be understood that a variety of substitutions and alterations are possible without departing from the spirit and scope of the present invention, as defined by the claims that follow.