Abstract:
Optical apparatus ( 20, 60 ) includes a spectacle frame ( 30, 64 ) configured to be worn by a user ( 22 ). A telescope ( 26, 62 ) is fixed to the spectacle frame and includes an objective ( 44 ), an eyepiece (28), and multiple optical surfaces ( 48, 56, 58 ) defining a folded optical path for providing a magnified image to an eye ( 40 ) of the user while at least one of the optical surfaces is located at least partially posterior to a coronal plane ( 41 ) located at a rear surface of the eyepiece.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 61/028,527, filed Feb. 14, 2008, which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to optical devices, and specifically to spectacle-mounted visual aids. 
       BACKGROUND OF THE INVENTION 
       [0003]    Various low-vision devices are available to improve the eyesight of people with macular degeneration. For example, there are a variety of magnifiers that enlarge print to make it easier to read. Such magnifiers include spectacles, telescopes, handheld or stand-alone magnifying glasses, and closed-circuit television devices. 
         [0004]    A number of telescopic devices have been developed for mounting on spectacle frames or embedding in spectacle lenses. For example, miniature Galilean or Keplerian telescopes may be fitted into bores made through the spectacle lenses (typically in the upper part of the lenses). As another example, U.S. Pat. No. 5,680,194 describes a periscopic telemicroscope for spectacles, which mounts over the periphery of one of the spectacle lenses. As yet another example, U.S. Pat. No. 6,972,903 describes a vision assisting apparatus that includes a casing for forming an inversely U-shaped optical path, with an attaching structure for attaching the casing to a wearer so that the light exit is positioned close to an eye of the wearer. 
         [0005]    An alternative type of arrangement is suggested by U.S. Pat. No. 6,775,060, which describes a bioptic telescope that is at least partially embedded in a spectacle lens. In one embodiment, the telescope includes a plurality of optical elements defining an optical path for viewing an object, such that at least a portion of the optical path is located within the spectacle lens in a plane substantially orthogonal to the vision axis. 
       SUMMARY OF THE INVENTION 
       [0006]    Embodiments of the present invention that are described hereinbelow provide improved telescopic spectacles, with a folded optical path. In some embodiments, the design takes advantage of space available within the bounds of the spectacle frame in order to lengthen the optical path, in order to achieve high magnification while maintaining a compact profile that is comfortable and unobtrusive for the user. The telescope may be integrated into the spectacle frame so as to appear aesthetically as a single unit. 
         [0007]    There is therefore provided, in accordance with an embodiment of the present invention, optical apparatus, including a spectacle frame configured to be worn by a user. A telescope is fixed to the spectacle frame and includes an objective, an eyepiece, and multiple optical surfaces defining a folded optical path for providing a magnified image to an eye of the user while at least one of the optical surfaces is located at least partially posterior to a coronal plane located at a rear surface of the eyepiece. 
         [0008]    In one embodiment, the telescope is contained inside a body of the spectacle frame. Typically, the apparatus includes a pair of telescopes fixed to the spectacle frame, for providing magnified images to both eyes of the user. In some embodiments, the spectacle frame includes a bridge piece and temples, and the at least one of the optical surfaces is located adjacent to a temple of the spectacle frame. 
         [0009]    In some embodiments, the at least one of the optical surfaces is a reflective surface, which folds the optical path at an acute angle, wherein the reflective surface is located on the optical path between the objective and the eyepiece. The objective is located adjacent to a temple of the spectacle frame in a position anterior to the reflective surface. In one embodiment, the reflective surface posterior to the coronal plane includes a first reflective surface, and the telescope includes at least a second reflecting surface located anterior to the coronal plane between the first reflective surface and the eyepiece for directing the optical path toward the eye. Optionally, the telescope includes an Amici roof prism, and the second reflecting surface includes a roof face of the Amici roof prism. 
         [0010]    In a disclosed embodiment, the telescope includes a Keplerian telescope. The at least one of the optical surfaces may be located at least partially posterior to a further coronal plane located at a front surface of the eye. 
         [0011]    In some embodiments, the apparatus includes a spectacle lens held in a first area within the spectacle frame, while the telescope is fixed in a second area within the spectacle, frame, so as to allow the user to view objects alternatively through the spectacle lens and through the telescope while wearing the spectacle frames. Typically, the first area is a lower area of the spectacle frame, while the second area is an upper area of the spectacle frame, and the spectacle lens is chosen so as to provide a refractive vision correction to the user. 
         [0012]    There is also provided, in accordance with an embodiment of the present invention, a method for magnification, including providing a telescope including an objective, an eyepiece, and multiple optical surfaces defining a folded optical path. The telescope is fixed to a spectacle frame so that when a user wears the spectacle frame, the telescope provides a magnified image to an eye of the user while at least one of the optical surfaces is located at least partially posterior to a coronal plane located at a rear surface of the eyepiece. 
     
    
     
         [0013]    The present invention will be more fully understood from the following detailed description of the embodiments thereof, taken together with the drawings in which: 
         BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a schematic, pictorial illustration showing telescopic spectacles worn by a user, in accordance with an embodiment of the present invention; 
           [0015]      FIG. 2  is a schematic, pictorial view of telescopic spectacles in accordance with an embodiment of the present invention; 
           [0016]      FIGS. 3A and 3B  are schematic profile views of a user wearing telescopic spectacles and looking through the spectacles at two different viewing angles, in accordance with an embodiment of the present invention; 
           [0017]      FIG. 4  is a schematic top view of telescopic spectacles worn by a user, in accordance with an embodiment of the present invention; 
           [0018]      FIGS. 5 and 6  are schematic, pictorial back and front views, respectively, of telescopic spectacles in accordance with another embodiment of the present invention; 
           [0019]      FIG. 7  is a schematic, exploded view of the telescopic spectacles of  FIGS. 5 and 6 , in accordance with an embodiment of the present invention; and 
           [0020]      FIG. 8  is an optical ray diagram that schematically shows optical components used in telescopic spectacles in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0021]    Reference is now made to  FIGS. 1 and 2 , which are schematic, pictorial illustrations showing telescopic spectacles  20 , in accordance with an embodiment of the present invention. In  FIG. 1 , the spectacles are worn by a user  22 , while  FIG. 2  shows the spectacles from the user&#39;s inside point of view. The spectacles comprise a frame  30 , which comprises a bridge piece  34  and temples  32 . (The bridge piece refers to the part of the frame that sits on the bridge of the nose, while the temples extend along the sides of the user&#39;s face and mount over the ears.) 
         [0022]    Frame  30  typically contains spectacle lenses  24  in one area and dual telescopes  26  in another area. Typically, the telescopes are held in the upper area of the frames, as shown in the figures, while the spectacle lenses occupy the lower area, but other arrangements are also possible. Spectacle lenses  24  may be chosen to provide a refractive vision correction to the user. Alternatively, if no refractive correction is needed or desired, the spectacle lenses may simply comprise transparent blanks or may be omitted altogether. 
         [0023]    Telescopes  26  are contained in a housing  36 , which extends both across bridge piece  34  and along temples  32 . The housing contains telescopic optics, which define an optical path that extends along the inside of the temples, as described in detail hereinbelow. The housing is typically designed fit inside the spectacle frames, and may actually be integrated into the spectacle frames, as shown in the figures, so as to maintain a compact, unobtrusive appearance. The front surface of the housing, above spectacle lenses  24 , may be coated with a reflective coating, for example, so as to blend with the spectacle lenses as though they were a single unit. The rear surface of the housing, including the optical path that it contains, extends inward beyond the adjacent inner surfaces of lenses  24 , particularly in the corners of the frame where the temples meet the bridge piece. 
         [0024]    For proper viewing through telescopes  26 , it is important that eyepieces  28  of the telescopes are well aligned with the user&#39;s eyes (as illustrated in  FIG. 1 ). To facilitate such alignment, bridge piece  34  may comprise an adjustment mechanism  38 , which shifts the telescopes transversely. Optionally, the adjustment mechanism may comprise two separate controls, for aligning eyepieces  28  individually with each of the user&#39;s eyes. 
         [0025]      FIGS. 3A and 3B  are schematic profile views of user  22  wearing telescopic spectacles  20  and looking through the spectacles at two different viewing angles, in accordance with an embodiment of the present invention. For normal distance vision, the user looks directly through spectacle lenses  24 , as shown in  FIG. 3A . To use telescopes  26 , the user inclines his head slightly downward and looks slightly upward, as shown in  FIG. 3B , so that the pupils of his eyes are aligned with eyepieces  28 . 
         [0026]      FIG. 4  is a schematic top view of telescopic spectacles  20  worn by user  22 , in accordance with an embodiment of the present invention. The user&#39;s eyes  40  are aligned with respective eyepieces  28 . The rear surfaces of the eyepieces (i.e., the surfaces closest to the user&#39;s eyes) define a first coronal plane  41 . The front surfaces of the eyes (i.e., the corneas) define a second coronal plane  42 . A “coronal plane” (also known as a frontal plane) refers to any vertical plane that divides the body into anterior and posterior (belly and back) sections. “Vertical” is used here in the usual sense to mean parallel to the long (spinal) axis of the body. The relevant examples of a coronal planes in the present case are planes  41  and  42 , which pass through the face at the nose or the front surface of the eyes. 
         [0027]    Each of telescopes  26  comprises an objective  44 , which is located adjacent to the temple of spectacles  20 . The optical path of the rays that are focused by each objective passes through a prism  46 , which is also adjacent to the temple. The optical path crosses coronal plane  41 . In this embodiment, the optical path also crosses coronal plane  42  and is then folded at an acute angle by a rear reflective surface  48  of prism  46 , which is located posterior to plane  42 . The optical rays are thus reflected forward to a deflector  50  and focused by a field lens  52 . The rays are then turned toward eyepiece  28  by a reflective roof face  56  of an Amici roof prism  54 , anterior to planes  41  and  42 . 
         [0028]    The telescope design that is shown in  FIG. 4  thus takes advantage of unused space within the corners of the spectacle frames, adjacent to temples  32 . This design provides both a long optical path—and thus high magnification, typically on the order of 2.2X to 4X—and an unobtrusive, aesthetic outward appearance. To enhance the magnification while maintaining small dimensions, the lenses in the telescope may comprise aspheric and/or diffractive optical elements, as are known in the art. Although the telescopes shown in  FIG. 4  are of the Keplerian type, other types of telescopes, including Galilean types and reflective types (with curved reflective surfaces), for example, may likewise be designed on the model shown in this figure, with folded optical paths extending behind plane  41  and possibly behind plane  42 . The telescope may contain a movable element (not shown) to permit focal adjustment. The above sorts of design are also suitable for monocular spectacle-mounted telescopes. 
         [0029]      FIGS. 5 and 6  are schematic, pictorial back and front views, respectively, of telescopic spectacles  60  in accordance with another embodiment of the present invention. Spectacles comprise dual telescopes  62 , which are integrated with frames  64 . The principles of the design and operation of spectacles  60  are similar to those of spectacles  20 , as described above, and like elements are labeled with the same numbers in both embodiments. Spectacles  60  are advantageous, however, in that telescopes  62  are integrated into the body of the spectacle frames. Spectacles  60  with telescopes  62  thus appear visually to the observer to be a single unit, rather than as a telescope added onto a pair of spectacles. 
         [0030]      FIGS. 7 and 8  schematically show internal details of spectacles  60 , in accordance with an embodiment of the present invention.  FIG. 7  is an exploded view of the spectacles, while  FIG. 8  is an optical ray diagram showing the optical components that are used in telescopes  62 . Certain components in this embodiment, particularly prism  46 , are foreshortened relative those in spectacles  20 , but the principles of operation of the design shown in  FIGS. 7 and 8  are similar to those used in the embodiment of  FIG. 4 . 
         [0031]    As shown in  FIG. 8 , rays focused by objective  44  pass through prism  46  and are folded at an acute angle by reflecting surface  48 . At least a portion of surface  48  is located behind plane  41 , which is the coronal plane defined by the rear surface of eyepiece  28 , as explained above. A further reflective surface  58  associated with deflector  50  turns the rays along a transverse axis, perpendicular to the optical axis of eye  40 . Roof face  56  of Amici roof prism  54  then turns the rays toward the eye, through eyepiece  28 . The Amici roof prism has the effect of inverting the image, so that the user sees an erect image through the telescope. 
         [0032]    As shown in  FIG. 7 , telescopes  62  are fitted into a hollow area within the upper part of the body of bridge piece  34  of spectacles  60 . Objectives  44  are secured in place by retaining rings  66 , while rear covers  68  enclose the telescopes from behind. Although  FIG. 8  shows surface  58  to be a part of deflector  50 , surface  58  may alternatively be fabricated as an integral part of prism  46 , as shown in  FIG. 7 . 
         [0033]    It will be appreciated that the embodiments described above are cited by way of example, and that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.