Patent Publication Number: US-2002003673-A1

Title: Panoramic imaging arrangement

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1). Field of the Invention  
       [0002] This invention relates to a panoramic imaging arrangement of the kind capable of capturing, focusing, correcting aberrations and otherwise manipulating light received from a 360° surrounding panoramic scene.  
       [0003] 2). Discussion of Related Art  
       [0004] Panoramic imaging arrangements have become popular in recent years for purposes of viewing 360° surrounding panoramic scenes. Older generations of panoramic imaging arrangements generally consisted of revolving periscope-like constructions having relatively complex mechanisms for revolving them. More recently, stationary panoramic imaging arrangements have been developed. A stationary panoramic imaging arrangement generally has one or more lenses, each having a vertical axis of revolution, which are used to refract or reflect light received from a 360° surrounding panoramic scene. The lenses alter the direction of the light, whereafter the light passes through a series of lenses which are located vertically one above the other and which further manipulate the light by, for example, focusing the light or altering the intensity of the light.  
       [0005] The task of receiving light in a sideways direction and altering the direction of the light so that the light then proceeds in a vertical direction is a difficult one. Altering the direction of light to such a degree, especially when coming from a 360° surrounding scene, oftentimes leads to aberrations in the resulting light. These aberrations may include astigmatism of the light, defects in color of the light, a loss of image plane flatness, and other defects, some of which are discussed in more detail herein below.  
       [0006] Relatively complex lenses and lens arrangements have been developed in order to overcome these aberrations and produce an acceptable image. These lens arrangements usually include a large number of lenses and oftentimes have lenses with surfaces which are aspherical (see for example U.S. Pat. No. 5,473,474 issued to Powell). Aspherical lenses are difficult to manufacture and therefore less practical to manufacture than for example spherical lenses.  
       SUMMARY OF THE INVENTION  
       [0007] According to one aspect of the invention there is provided a panoramic imaging arrangement comprising a transparent component and a reflective material. The transparent component has a first surface about a vertical axis of revolution, a second, substantially spherical, surface about the axis of revolution, and an opening formed therein to define a third, internal surface about the axis of revolution. The third surface has a concave profile in a plane of the axis of revolution. The reflective material is located on the second surface to provide a reflective surface against the second surface. The first surface, the reflective surface and the third surface are positioned relative to one another so that light from a 360° surrounding panoramic scene enters the transparent component through the first surface, whereafter the light is reflected from the reflective surface, whereafter the light exits the transparent component through the third surface.  
       [0008] The first surface may have a convex profile in a plane of the axis of revolution and is preferably substantially spherical.  
       [0009] The first surface and the reflective surface are preferably located on opposing sides of the transparent component and the reflective surface preferably has a convex profile in plane of the axis of revolution.  
       [0010] Preferably, at least extensions of the first surface and the reflective surface intersect one another.  
       [0011] The third surface is preferably substantially spherical.  
       [0012] In one embodiment the first surface, the reflective surface and the third surface are all substantially spherical and have a radiuses which are in the relationship of about 21 units for the first surface, about 40 units for the reflective surface, and about 7 units for the third surface.  
       [0013] At least extensions of the first surface and the reflective surface may intersect the axis of revolution at respectively first and second locations which may be about 9 units displaced from one another.  
       [0014] At least an extension of the third surface may intersect the axis of revolution at a third location which is about 0.5 units displaced from the second location.  
       [0015] The panoramic imaging arrangement may further comprise a system of lenses positioned to receive the light after exiting the transparent component, the system of lenses at least focusing the light. The light is preferably focused in a plane which is substantially flat.  
       [0016] Preferably, the light passes through a total of less than five lenses from exiting the transparent component until being focused.  
       [0017] The panoramic imaging arrangement may further comprise a mirror which reflects the light after exiting the transparent component. A hole may be formed through the transparent component with the opening forming at least part of the hole. The light may at least partially pass through the hole after being reflected by the mirror and before passing through the system of lenses. The mirror may be curved and preferably has a concave reflective area.  
       [0018] According to a further aspect of the invention a panoramic imaging arrangement is provided comprising a transparent component and a reflective material. The transparent component has first and second surfaces, both about a vertical axis of revolution. The first surface has a convex profile in a plane of the axis of revolution. The second surface has a concave profile in a plane of the axis of revolution. At least extensions of the first and second surfaces intersect one another. The reflective material is located on the second surface to provide a reflective surface against the second surface. The first surface and the reflective surface are positioned relative to one another so that light from a 360° surrounding panoramic scene enters the transparent component through the first surface, whereafter the light is reflected from the reflective surface.  
       [0019] The second surface may be substantially spherical.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
     [0020] The invention is further described by way of example with reference to the accompanying drawing which is a sectioned side view of a panoramic imaging arrangement, according to an embodiment of the invention, in a plane of a vertical axis of revolution thereof.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0021]FIG. 1 of the accompanying drawings illustrates a panoramic imaging arrangement  10 , according to an embodiment of the invention, in a plane of a vertical axis of revolution  12  thereof. The panoramic imaging arrangement  10  includes a lens block  14 , a mirror  16 , and a system of lenses  18 .  
     [0022] The lens block  14  includes a transparent component  20  having a first, upper, convex surface  22  symmetrically about the axis of revolution  12  and a second, lower, concave surface  24  also symmetrically about the axis of revolution  12 . A reflective material  26  is formed on the lower, concave surface  24 . A hole  28  is formed vertically through the transparent component  20 .  
     [0023] The upper, convex surface  22  of the transparent component  20  is spherical and has a radius of about 21.310 mm. An extension of the upper, convex surface  22  intersects the axis of revolution  12  and a first location  32 .  
     [0024] The lower, concave surface  24  of the transparent component  20  is spherical and has a radius of about 40.200 mm. Extensions of the upper, convex surface  22  and of the lower, concave surface  24  intersect one another due to the larger radius of the lower, convex surface  24  with respect to the radius of the upper, convex surface  22 . An extension of the lower, concave surface  24  intersects the axis of revolution  12  and a second location  36  which is located about 9 mm below the first location  32  where the extension of the upper, convex surface  22  intersects the axis of revolution  12 .  
     [0025] By forming the reflective material  26  on the lower, concave surface  24 , the reflective material  26  provides a concave reflective surface  38  against the lower, concave surface  24  and conforming in shape thereto.  
     [0026] An upper portion of the hole  28  is formed by an opening defining a third, internal surface  40  of the transparent component  20 . The internal surface  40  is located symmetrically about the axis of revolution  12 . The internal surface  40  is spherical and has a concave profile with a radius of about 7.650 mm. An extension of the internal surface  40  intersects the axis of revolution  12  at a third location  44  which is located about 0.5 mm above the second location  36  where the extension of the lower, concave surface  24  (and therefore also of the reflective surface  38 ) intersects the axis of revolution  12 .  
     [0027] The mirror  16  is secured to the transparent component  20  at a location over the hole  28 . The mirror  16  has a concave reflective area  46  which is spherical and is located symmetrically about the axis of revolution  12 . The reflective area  46  has a radius of about 87.750 mm and intersects to the axis of revolution  12  at a fourth location  48  which is located about 8.115 mm above the third location  44  where an extension of the internal surface  40  intersects the axis of revolution  12 .  
     [0028] The system of lenses includes a first, upper lens  50  located within a lower portion of the hole  28 , a second, intermediate lens  52  located below the upper lens  50 , and a third, lower lens  54  located below the intermediate lens  52 . The upper lens  50  has a convex upper surface  56  with a radius of about 18.000 mm and a lower surface with a radius of about 20.475 mm. The intermediate lens  52  has an upper, convex surface  60  with a radius of about 6.060 mm and a lower, concave surface  62  with a radius of about 4.700 mm. The lower lens  54  has an upper, concave surface  64  with a radius of about 10.550 mm and a lower, convex surface  66  with a radius of about 5.325 mm. Other features of the upper, intermediate and lower lenses  50 ,  52  and  54  are not discussed further in detail herein as these features would be evident to one of ordinary skill in the art.  
     [0029] In use, the light from a 360° surrounding panoramic scene enters the transparent component  20  through the upper, convex surface  22 . Light is received from the surrounding panoramic scene for an unbroken included angle  72 , in a vertical plane of the axis of revolution  12 , extending from an angle  74  which is located about 30° below the horizon to an angle  76  which is located about 30° above the horizon. By extending the upper, convex lens  22  or altering its shape, the angle  76  below the horizon may be increased. When the light enters the transparent component  20 , the light is refracted slightly downwardly by the upper, convex surface  22 , thus reducing the angle of the light with respect to vertical. The light then passes through the transparent component  20  and is then reflected upwardly by the reflective surface  38 . Due to be convex shape of the reflective surface  38 , the angle of the light with respect to vertical is further reduced after reflection from the reflective surface  38 . The light then passes through the transparent component  20  and exits the transparent component through the internal surface  40 . Due to the concave shape of the internal surface  40 , the light is refracted slightly upwardly when exiting the transparent component  20  through the internal surface  40 , thus further reducing the angle of the light with respect to vertical.  
     [0030] After leaving the transparent component, the light passes upwardly through the hole  28  and is reflected downwardly by the reflective area  46  of the mirror  16 . The light then passes downwardly through the hole  28  and Thereafter it is refracted respectively by the upper lens  50 , the intermediate lens  52 , and the lower lens  54 . The light, after leaving the lower lens  54 , is focused by creating a flat image on a flat focal plane  78 .  
     [0031] It can be seen from the aforegoing description that a simple, compact arrangement is provided which is capable of capturing a view of a 360° surrounding panoramic scene. In particular, the panoramic imaging arrangement  10  includes only five components namely the lens block  14 , the mirror  16  and the upper, intermediate and lower lenses  50 ,  52  and  54 . Moreover, all the surfaces of the panoramic imaging arrangement  10  which manipulate light are spherical or substantially spherical so as to be easily manufacturable.  
     [0032] A final image is created which is corrected for image flatness and astigmatism. It could be noted that no particular surface or surfaces correct for image flatness and astigmatism, but rather that the sizes, positioning and orientations of all the surfaces cooperate to produce a final image which is corrected for image flatness and astigmatism. It has been found that the panoramic imaging arrangement  10  is particularly suitable for creating a monochromatic image of the surrounding panoramic scene. One of ordinary skill in the art would appreciate that the panoramic imaging arrangement  10  may be modified or may be complemented by additional lenses which would make it more suitable for capturing color images of a surrounding panoramic scene.  
     [0033] While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive of the current invention, and that this invention is not restricted to the specific constructions and arrangements shown and described, since modifications may occur to those ordinarily skilled in the art.