Abstract:
A lens processing system used for removing a lens blank ( 98, 110 ) from an edging block ( 40 ). The system includes an elongated collet ( 22 ) that engages the mating edging block ( 40 ). The block ( 40 ) includes an enlarged groove ( 41 ) that receives a pair of blades ( 65, 66 ) extended upwardly from the floor ( 75 ) of the collet ( 22 ). Each lens blank ( 98,110 ) is formed to include a series of surface markings ( 191,192 ) to verify proper functioning of the edging machine that forms a finished lens. Each lens blank also includes a series of circular markings ( 117,133 ) arranged in diagonal rows to verify the accurate drilling of bores with the lens blank ( 98,110 ).

Description:
[0001]    This patent application is based on Provisional Patent Application No. 61/707,795, filed on Sep. 28, 2012. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of Invention 
         [0003]    This invention pertains generally to the field of lens fabrication and more particularly to inspecting and processing a lens during manufacture. 
         [0004]    2. Description of Prior Art 
         [0005]    The fabrication of lenses includes processing steps to generate both lens surfaces in order to impart specific optical properties to the lens, and also to accomplish the peripheral alteration, or edging, of the lenses. The first step in altering a lens is typically the generation of a surface on a partially finished lens blank. The second step in processing the lens is normally the peripheral alteration of the shape of the surfaced lens. The lens blanks and surfaced lenses may be, for example, spherical, cylindrical, optical flats, aspherical, or of multiple focal lengths. Once the lenses have been finished they may be put to a variety of uses such as spectacle lenses, camera lenses, or lenses used in instrumentation. 
         [0006]    Edging the lens to obtain a desired shape involves a series of steps. Typically the optical center and the cylinder axis of the lens is located and marked on a surface. Next the lens is attached to a lens block by some type of holding mechanism, such as an adhesive, so that the optical center and the cylinder axis of the lens are aligned with the center point and cylinder axis of the block. The desired peripheral shape is then imparted to the lens via one or more drilling, cutting, milling, grinding or other machining tools. 
         [0007]    Typically the lens cutting and shaping tool is a computer controlled programmable device that may be frequently reprogrammed to manufacture a wide variety of lenses. In order to verify proper programming and operation of the lens forming tool, some means of calibration must be provided. 
         [0008]    For example, U.S. Pat. No. 7,191,030, entitled “METHOD FOR ESTIMATING THE ANGULAR OFFSET, METHOD FOR CALIBRATING A GRINDING MACHINE FOR OPTHALMIC GLASSES AND DEVICE FOR CARRYING OUT SAID CALIBRATING METHOD” utilizes a reference standard lens of a predetermined known shape. 
         [0009]    U.S. Pat. No. 7,668,617 entitled “METHOD OF CALIBRATING AN OPTHALMIC LENS PIERCING MACHINE, DEVICE USED TO IMPLEMENT ONE SUCH METHOD AND OPTHALMIC LENS MACHINING APPARATUS COMPRISING ONE SUCH DEVICE”, uses a template marked with an associated coordinate system. An additional drilling calibration device is used to calculate the difference between the apparent markings on the template and the actual drilling angles needed to create the desired lens. 
         [0010]    U.S. Pat. No. 7,970,847 entitled “METHOD OF CALIBRATING AN OPTHALMIC LENS PROCESSING DEVICE, MACHINE PROGRAMMED THEREFOR, AND COMPUTER PROGRAM”, presents a scheme for comparing the number of holes actually drilled in a lens with the number of holes predicted according to the programming of a drilling device. 
         [0011]    Further, some means must be provided to attach the lens blank to the edging block with a bond that will not fail during alteration but that will permit removal once alteration is complete. In practice, the lens may be removed from the edging block by a variety of methods. For example, the lens may be pried from the block. However, this method has the disadvantage that the lens is often chipped, scratched, or otherwise damaged by the act of prying. This method can be facilitated by immersing the lens and block in hot water for a short period of time. However, some plastic lens materials cannot withstand such temperatures. 
         [0012]    Another method of lens removal employs a tab that is pulled in the direction of the plane of the blocking pad so as to cause a reduction in the thickness of the pad and a progressive disengagement of the pad from the interface between lens and block. Removal may also be accomplished by placing the combination of lens, blocking pad and block into a cavity of the mounting block and then rotating the lens and the block in opposite directions with respect to each other, thereby causing them to separate. A specially designed hand tool may also be provided to accomplish this same result. The tool is not as wide as the mounting block and facilitates removal by making it easier to grasp the edge of the lens. 
         [0013]    The latter method of lens removal is disclosed in U.S. Pat. No. 3,962,833 entitled METHOD FOR THE ALTERATION OF A LENS AND AN ADHESIVE LENS BLOCKING PAD USED THEREIN, issued to Johnson on Jun. 15, 1976. The problem with the lens removal method disclosed by Johnson is that an operator must manually and repeatedly grasp pliers or a similar tool to remove the lens. Some level of skill is required to perform the lens removal operation rapidly while avoiding damage to the lens. After a period of time in such an occupation, the operator is likely to suffer various forms of fatigue and injury including, for example, carpal tunnel syndrome. 
         [0014]    Another method of lens removal utilizes a device that retains the blocked lens by means of a collet chuck or clamp. An example of such a device is disclosed in U.S. Pat. No. 8,182,314 entitled AUTOMATED EDGED LENS DEBLOCKING SYSTEM, issued to Goerges on May 22, 2012. The blocked lens resides on a pad which supports the lens on the edging block while protecting the lens from abrasion or damage from the block itself. A pair of opposed movable lens clamps or arms are pneumatically advanced to grip the blocked lens along portions of the lens edge. Once the lens is secured by the lens clamp, the collet chuck is rotated approximately forty five degrees, thereby breaking the bond between the lens and the edging block. The lens clamps may then be retracted away from the lens edges and the lens may be manually removed from the pad. 
         [0015]    A problem with the geometry of the &#39;314 device is that repeated use causes wear on the collet chuck that leads to relatively premature failure, particularly when a hydrophobic adhesive pad is applied to an uncoated lens. Use of the hydrophobic pad requires a substantially greater force for lens removal than other pad/lens combinations, thereby accelerating the wear on both the collet and the edge block. 
         [0016]    What is needed is a visually verifiable lens template that permits a wide variety of lens parameters to be immediately inspected after a lens machining tool is programmed to create a specific lens. Any error or anomaly in the lens created, and the nature of the corrective action needed, should be apparent by viewing the lens template without further need of a machine based analysis. Further, the edged lens deblocking device must be capable of repeated industrial scale operation without failure. 
       SUMMARY OF THE INVENTION 
       [0017]    The current invention is an improved apparatus and method for processing a lens that has undergone an edging procedure, including an improved apparatus for the removal of a lens from an edging block and a means for verifying the integrity and accuracy of the edging process performed on the lens. The edged lens is freed from an adhesive pad by the twisting motion of a collet. Periodically the edged lens is a calibration blank which may be inspected for compliance with the desired edging operations. 
         [0018]    In a preferred embodiment of the invention, a blocked lens is placed on each collet, the collet being formed to include an elongated cylindrical body that mates with an existing deblocking device such as the type described in the aforementioned U.S. Pat. No. 8,182,314. The collets are formed with a series of circumferential ribs surrounded by a larger circumferential wall that defines a bore. The edging blocks are formed to include a mating groove structure that accepts protrusions formed within the base of the bore. Some of the edging blocks are periodically affixed to a calibration blank having a series of parallel and intersecting lines, as well as circles or portions of circles, the lines and circles permitting rapid visual inspection of the edging or machining processes performed on the lens. These and other advantages of the present invention will become apparent by referring to the accompanying drawings and the detailed description of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective view of a prior art automated edged lens deblocking system; 
           [0020]      FIG. 2  is a perspective view of an automated edged deblocking system constructed according to the principles of the present invention; 
           [0021]      FIG. 3  is a perspective view of detail  24  of the automated edged deblocking system depicted in  FIG. 2 ; 
           [0022]      FIG. 4  is a perspective view of the portion of the present invention indicated by rectangle  25  in  FIG. 2 , with the chassis cover removed; 
           [0023]      FIG. 5  is a bottom plan view of the prior art edging block depicted in  FIG. 4 ; 
           [0024]      FIG. 6  is a sectional view of the prior art edging block depicted in  FIG. 1  taken along line  6 - 6 ; 
           [0025]      FIG. 7  is a perspective view of an edging block constructed according to the principles of the present invention; 
           [0026]      FIG. 8  is a bottom plan view of the edging block depicted in  FIG. 7 ; 
           [0027]      FIG. 9  is a sectional view of the edging block illustrated in  FIG. 8 , taken along line  9 - 9 ; 
           [0028]      FIG. 10  is a detail view of the edging block depicted in  FIG. 9 , as indicated by the circle  10 ; 
           [0029]      FIG. 11  is a perspective view of a one piece collet constructed according to the principles of the present invention; 
           [0030]      FIG. 12  is a top plan view of the collet depicted in  FIG. 11 ; 
           [0031]      FIG. 13  is a sectional view of the collet depicted in  FIG. 12 , taken along line  13 - 13 ; 
           [0032]      FIG. 14  is a detail view of the collet depicted in  FIG. 13 , illustrating the region within the circle  14 ; 
           [0033]      FIG. 15  is a detail view of the collet depicted in  FIG. 14 , illustrating the region within the circle  15 ; 
           [0034]      FIG. 16  is a top plan view of a second embodiment of the collet of the present invention; 
           [0035]      FIG. 17  is a top plan view of the collet of  FIG. 11  and an alternate embodiment of an edging block combined to create a lens blank manipulation assembly; 
           [0036]      FIG. 18  is a sectional view taken along line  18 - 18  as shown in  FIG. 17 . 
           [0037]      FIG. 19  is a side elevation of the second embodiment of the collet depicted in  FIG. 16  shown and the edging block depicted in  FIG. 7  combined to create a lens blank manipulation assembly; 
           [0038]      FIG. 20  is a sectional view taken along line  20 - 20  as shown in  FIG. 19 ; 
           [0039]      FIG. 21  is a side elevation of a collet closer as used in conjunction with the present invention; 
           [0040]      FIG. 22  is a sectional view taken along line  22 - 22  as seen in  FIG. 21 ; 
           [0041]      FIG. 23  is a front elevation view of a first embodiment of a calibration lens constructed according to the principles of the present invention; 
           [0042]      FIG. 24  is a front elevation view of a second embodiment of a calibration lens constructed according to the principles of the present invention, including dimensional information; 
           [0043]      FIG. 25  is a sectional view of the calibration lens illustrated in  FIG. 24  taken along the line  25 - 25 ; 
           [0044]      FIG. 26  is a detail view of the calibration lens as illustrated in  FIG. 24  within the region  26 ; 
           [0045]      FIG. 27  is a front elevation view illustrating a calibration standard used in conjunction with the present invention; 
           [0046]      FIG. 28  is a front elevation view illustrating the utilization of a first calibration lens constructed according to the present invention, showing the portion of the calibration lens that remains after the calibration lens has undergone machining operations; and 
           [0047]      FIG. 29  is a front elevation view illustrating the utilization of a second calibration lens constructed according to the principles of the present invention, showing only the portion of the calibration lens that remains after the lens has undergone desired machining operations; and 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0048]    Referring to  FIG. 1 , a prior art automated edged lens deblocking device is shown generally at  1 . The deblocking device  1  includes a protective cabinet  2  typically composed of a durable metal or plastic material. The top surface  9  of the cabinet  2  is formed to include a generally rectangular aperture or slot  3  above which a pair of opposed arms  4  and  5  are slidably mounted by means of supports  6  and  7 . The supports  6  and  7  permit movement of the arms  4  and  5  in the directions generally indicated by arrow  8 . The top surface  9  also includes an opening or first circular aperture  10  which permits access to a first collet or edging block clamp  11 . A second circular aperture  12  is located in a symmetrical position opposite the rectangular aperture  3 . The circular aperture  12  permits access to a second collet or edging block clamp  13 . 
         [0049]    The edging block clamp  13  is intended to mate with an edging block. As seen in  FIGS. 5 and 6 , a prior art edging block  28  includes a series of inclined surfaces, such as surfaces  29 ,  30 ,  31  and  32 , for example. Additionally the block  28  includes a diametric groove  33  which broadens to a keyway  34  at one end. The block  28  also contains a pair of substantially circular indentations  35  and  36 . At least some of the features such as the surfaces  29 - 32 , the groove  33 , the keyway  34 , the indentation  35  and indentation  36  are adapted to mate with and be gripped either by or within an edging block clamp, such as clamp  11 , when the block  28  is placed on the clamp  11  and toggle switch  19  is activated. The greatest diameter  37  is typically 0.707 inch with a thickness  38  of 0.110 inch. The depth  39  of the groove  33  is 0.085 inch. 
         [0050]      FIGS. 2 ,  3  and  4  illustrate the present invention, which includes a first elongated collet  22  and a second elongated collet  23 . The first elongated collet  22  extends through the first circular aperture  10 , while the second elongated collet  23  extends through the second aperture  23 . With the top surface  9  of the cabinet  2  removed, the first elongated collet  22  is seen to be mounted on first collet closer  26 . The second elongated collet  23  is mounted on a second collet closer  27 . 
         [0051]      FIGS. 7 ,  8 ,  9  and  10  depict a novel edging block  40  that is intended for use with the elongated collets  22  and  23 . The edging block  40  includes a series of inclined surfaces such as surfaces  43  and  44 , for example, that are shaped and dimensioned to engage the collet  22 . The circumferential space occupied by each surface  43  or  44 , for example, is approximately 7.5 degrees, creating an angle  47  of approximately 15 degrees between two adjacent surfaces or an angle  48  of approximately 22.5 degrees between three successive surfaces. The present invention also includes a plurality of circular bores  45  and  46  for engagement with suitable fixtures that may be used to secure the edging block during lens machining operations. The edging block  40  includes a centrally located groove  41  terminating at keyway  42 . As best seen in  FIG. 9 , the groove  41  includes a blade or protrusion  49  extending from the bottom surface  50  of the groove for a distance  51  of approximately 0.080 inch. The angle  53  between the sidewall  52  of blade  49  and the bottom surface  50  is approximately 91 degrees. The length  54  of the blade  49  is approximately 0.145 inch. The outer lip  55  of the edging block  40  has a thickness  56  of approximately 0.110 inch, while the diameter  57  between the opposed inclined surfaces  58  and  59  is approximately 0.707 inch. The overall height  60  of the edging block  40  is approximately 0.316 inch, while the depth  61  of groove  41  is approximately 0.205 inch. 
         [0052]    The elongated collet  22  that receives the edging block  40  is depicted in greater detail in  FIG. 11 . The elongated collet  22  is formed to include a generally cylindrical sidewall  62  that is partially separated by three longitudinal slots  63 ,  64  and  74 . Each slot, such as slot  63 , extends through a frustoconical transition  69  that terminates at lip  70 . Integrally formed with and adjoining the transition  69  is a turret  76  that surrounds a base  75 . Also integrally formed with the sidewall  62  is a base  72  which includes at least one keyway  73  that is adapted to mate with a motor, gear, piston or other fixture that can rotate the elongated collet about the longitudinal axis  235 . Typically, the base  72  includes threads that are compatible with a receptacle such as a collet closer. 
         [0053]    Referring also to  FIG. 12 , a pair of protruding plates or fingers  65  and  66  is seen to extend upwardly from the base  75  of turret  76 , the plates being suitably dimensioned to fit within the groove  41  of edging block  40 . The thickness  77  of each plate  65  and  66  is approximately 0.060 inch. The distance  80  between the outer end  78  of plate  66  and the outer end  79  of the plate  65  is approximately 0.450 inch. The turret  76  also includes an inner wall  81  and an outer wall  71 , the inner wall  81  being formed to include a series of substantially equally spaced columns, such as columns  67  and  68  for example. The columns engage with the edging block surfaces  43  and  44 , for example, to add further stability to the edging block  40  when mounted to the turret  76 . The angular distance  212  between adjacent columns is approximately thirty degrees. The greatest angular distance  83  between the lateral axis  82  of the plate  65  and the farthest adjacent inner wall column  84  is approximately twenty degrees. 
         [0054]    As best seen in  FIG. 13 , the height  85  of each inner wall column, such as column  96 , for example is approximately 0.145 inch. The clearance  88  between the top surface  86  of the turret  76  and the top surface  87  of the plate  66  is approximately 0.025 inch. The overall length  89  of the elongated collet  22  is approximately three inches. The distance  90  between the base  75  and the top surface  86  of the turret  76  is approximately 0.210 inch. Referring also to  FIGS. 14 and 15 , the height  93  of the plate  66  is 0.185 inch. The base width  91  of the plate  66  is approximately 0.060 inch while the plate sidewall taper  92  is approximately four degrees. The cross sectional width  94  of each inner wall column, such as column  97 , for example, is approximately 0.016 inch and the height  95  of column  97  is approximately 0.020 inch. 
         [0055]      FIGS. 16 ,  19  and  20  depict an alternate embodiment 217 of the elongated collet  22 . The turret  218  is formed to include four longitudinal slots  219 ,  220 ,  221  and  222 . The result is the creation of four individual tangs  223 ,  224 ,  225  and  226 , the tangs  223  and  224  being deformable in a direction parallel to line  227  while tangs  225  and  226  may be deflected in a direction that is parallel to the line  228 . Sixteen individual columns, such as columns  229 ,  230 ,  231  and  232  are formed on the inner wall  233  of the turret  218 , arranged symmetrically such that four columns each reside on any individual tang  223 - 226 . Each column protrudes outwardly from the inner wall  223  by a distance  234  of approximately 0.044 inch. 
         [0056]    The elongated collet  217  includes a pair of upwardly extending blades  236  and  237  adapted to engage the edging block  40 . The elongated collet  217  permits the application of a greater force to an edging block  40  inserted into the turret  218 , thereby suppressing movement of the edging block with respect to the inner wall  223  during rotation of the elongated collet. Both the elongated collets  22  and  217  are formed of a metallic alloy manufactured by Hardinge, Inc. of Elmira, N.Y. The inner wall  223  may be coated with a diamond film or surface texture in order to further reduce wear caused by differential motion between the collet and the edging block. 
         [0057]    Referring to  FIGS. 17 and 18 , a modified edging block  40   a  is depicted. The edging block  40   a  is substantially similar to the edging block  40  disclosed in  FIG. 7 , except that the circular perimeter  214  of the edging block  40   a  is interrupted by the two parallel sidewalls  215  and  216 , thereby creating a relatively smaller surface area for the edging block  40   a . The geometry of the block  40   a  is useful for mounting smaller lenses so as not to interfere with edging tools that may be employed in shaping a smaller lens. The edging block  40   a  is mounted on the turret  76 . The central protrusion  49   a  of the edging block  40   a  fits snugly between the blades  65  and  66  of the turret  76  to create a unified assembly capable of resisting a substantial torsional force. 
         [0058]      FIGS. 21 and 22  illustrate the collet closer  238  that grips and rotates the elongated collet  217 . The collet closer  238  operates generally as disclosed in U.S. Pat. No. 5,221,098 entitled “Collet Closer”. The first inlet orifice  240  permits the application of pressure to unclamp the collet  217 , while the second inlet orifice  241  permits the application of pressure to clamp the collet  217 . The bore  239  permits access to a set screw residing in threaded chamber  242 , thereby permitting the collet  217  to be secured within the collet closer  238 . 
         [0059]    The calibration lens blank  98  depicted in  FIG. 23  is an example of a lens blank that may be manipulated by the combination of the elongated collet  22  and edging block  40 . The calibration lens  98  includes a series of calibration markings such as an alignment cross  99 , vertical lines  100  and  101 , and horizontal lines  102 ,  103 ,  104  and  105 . A plurality of circles, such as circles  106 ,  107 ,  108  and  109 , are also formed on the lens blank  98  by means of drawing, etching, engraving, painting or other surface marking techniques. In practice, the line and circle configuration of blank  98  may be varied, but this particular example is illustrative of the basic geometrical features of the present invention. 
         [0060]    A second embodiment of a calibration lens blank  110  is illustrated in  FIGS. 24 ,  25  and  26 , showing a lens blank having sixteen circular markings arranged in a pattern with respect to a horizontal axis  112  and a vertical axis  111 . In practice, the lens blank  110  is manufactured in two forms, both of which are geometrically identical. However, one version is composed of polycarbonate, while the other version is made of allyl diglycol carbonate, a plastic polymer commonly referred to as CR39. The polycarbonate material is more difficult to shape using traditional cutting tools, meaning that a version of lens blank  110  would often require different tool pressure settings when being processed by an automated shaping device. In order to verify the proper operation of a highly automated shaping apparatus, both a polycarbonate and a CR39 lens blank  110  are shaped by the same device in order to determine if the cutting tool is properly adapting to each material to produce a substantially identical lens. 
         [0061]    The first circular marking  113  on lens blank  110  is placed at a distance  114  of approximately 0.610 inch from the vertical axis  111  and at distance  115  of approximately 0.198 inch from the horizontal axis  112 . The horizontally adjacent second circular marking  117  is spaced at a distance  118  of approximately 0.753 inch from the vertical axis  111 . Vertically offset from the circular markings  113  and  117  is a horizontal row composed of circular markings  120  and  119 . The innermost marking  119  resides at a distance  121  of approximately 0.079 inch from the horizontal axis  112  and at a distance  123  of approximately 0.753 inch from the vertical axis  111 . The outermost marking  120  is placed at a distance  122  of approximately 0.812 inch from the vertical axis  111 . The circular markings  113  and  117  define a first horizontal row, while circular markings  119  and  120  define a second horizontal row. 
         [0062]    A third horizontal row of circular markings, residing above the horizontal axis  112 , is defined by the circular markings  124  and  125 . The marking  124  is displaced a distance  126  of approximately 0.079 inch from the horizontal axis  112  and by a distance  127  of approximately 0.871 inch from the vertical axis  111 . Ideally, the distances  121  and  126  are substantially equal. The horizontally adjacent circular marking  125  is displaced by a distance  128  of approximately 0.733 inch from the vertical axis  111 . 
         [0063]    Markings  124 ,  125 ,  129  and  130  define a horizontal row that is symmetrically spaced about the vertical axis  111 . The markings  124 ,  125 ,  129  and  130  indicate that a single type of lens may be fastened on either a right or left side to a spectacle lens frame, for example. This requirement creates the need for calibration marks that are symmetrical about the single vertical axis  111 . A fourth horizontal row is composed of circular markings  131 ,  132 ,  133  and  134 . Circular marking  131  is displaced a distance  135  from the vertical axis  111  by approximately 0.931 inch. The marking  132  is displaced from the vertical axis  111  by a distance  136  of approximately 0.792 inch. Each of the markings  131 ,  132 ,  133  and  134  is displaced from the horizontal axis  112  by a distance  137  of approximately 0.198 inch. The circular markings  113 ,  119 ,  125  and  132  form one of four diagonal rows appearing on the calibration lens  110 . The four rows of circular markings permit four successive uses of the calibration lens  110 , moving inwardly from the outermost hole  131  to the innermost hole  113 . 
         [0064]    The calibrations lens  110  includes four pairs of horizontal linear markings. The first pair of linear markings is composed of lines  138  and  139  which are spaced apart by a distance  140  of approximately 1.969 inch. The second, adjacent pair of linear markings includes lines  141  and  142  which are separated by a distance  143  of approximately 1.732 inch. The third adjacent pair of linear markings consists of horizontal lines  144  and  145 , spaced apart by a distance  146  of approximately 1.309 inch. The innermost pair of horizontal linear markings is formed by lines  147  and  148  which are separated by a distance  149  of approximately 1.084 inch. The four pairs of horizontal lines permit the calibration lens  110  to be used four separate times, that is, as material is successively removed during the edging process, the line  138  is initially consumed, the second edging pass references line  141 , the third edging pass utilizes line  144 , and finally the only reference line remaining for use is the line  147 . 
         [0065]    Three pairs of vertical linear markings are formed on calibration lens  110 . The outermost pair of vertical linear markings is composed of lines  150  and  151 , separated by a distance  152  of approximately 1.969 inch. The lines  150  and  151  extend vertically so as to terminate at the perimeter  154  of the lens  110 , where they join the horizontal lines  138  and  139 . A second pair of vertical linear markings includes vertical lines  153  and  155 , each of which terminates at the horizontal lines  141  and  142 . The spacing  156  between lines  153  and  155  is approximately 1.732 inch. A third pair of vertical linear markings consists of vertical lines  157  and  158 , which each have a lower end that is spaced a distance  159  of approximately 0.398 inch from the horizontal axis  112 . 
         [0066]    The upper ends of the lines  157  and  158  reside at a distance  160  from the horizontal axis  112  of approximately 1.043 inch. The parallel vertical lines  157  and  158  are spaced apart from each other by a distance  161  of approximately 1.335 inch. As best seen in  FIG. 18 , the outer radius  162  of the lens  110  is approximately 3.497 inches, the lens  110  having a thickness  163  of approximately 0.087 inch. The overall distance  166  between the top surface  164  and the bottom surface  165  is approximately 2.812 inches. The central region of the calibration lens  110  is best viewed in  FIG. 26 , which includes a tee  167  which is formed to have a horizontal section  168  that has a length  169  of approximately 0.158 inch. The lower tip  170  of tee  167  is spaced apart from the horizontal axis  112  by a distance  171  of approximately 0.039 inch. Horizontal section  168  is displaced from the horizontal axis  112  by a distance  172  of approximately 0.157 inch. A pair of horizontal linear markings  174  and  175  overlay the horizontal axis  112 . The end  176  of the horizontal marking  174  is offset from the vertical axis  111  by a distance  173  of approximately 0.039 inch. 
         [0067]    The vertical and horizontal lines just described define rectangles that replicate two types of machine calibration standards commonly used in the spectacle lens industry. The first calibration standard is used in association with equipment manufactured by National Optronics, 100 Avon Street, Charlottesville, Va., while the second standard is a development of Precision Tool Technologies, 924 Wright Street, Brainerd, Minn. 
         [0068]      FIG. 27  depicts an example of a machine calibration standard device  197 , which is formed to include two exemplary lens shape cutouts or pockets  198  and  199  having a specific geometry and dimensions. The overall width  200  of the standard device  197  is approximately five inches, while the overall height  203  is approximately two inches. The distance  201  between the left edge  207  of the standard device and the left edge  209  of lens pocket  199  is approximately 2.972 inches. The distance  202  between left edge  207  and the left edge  208  of the lens pocket  198  is approximately 0.261 inch. The height  204  of the lens pocket  199  is approximately 1.0977 inches, while the width  206  of the lens pocket  199  is approximately 1.767 inches. The radius  205  of each corner  210  is approximately 0.375 inch. 
         [0069]    The geometry and dimensions of each lens pocket  198  and  199  are identical. Each lens pocket defines an internal circumference  211  which extends continuously around each pocket  198  and  199 . In practice, a stylus, feeler gauge or other sensor travels along the circumference  211  to define the shape and size of a lens which is to be formed by a cutting or edging device associated with the sensor. In this manner the particular geometry of the pocket  198 , for example, is transferred to the edging device and is typically accessible to an operator of the edging device via a graphical user interface or other convenient means. The machine operator is then free to generate a drawing or display which indicates the desired configuration of a finished lens which may then be compared to the lens blank  98 . 
         [0070]      FIG. 28  illustrates the use of the lens blank  98  that is depicted in  FIG. 23 . A lens  178  is shown that results from an edging process performed on the blank  98 . In other words, only the lens  178  remains after machining blank  98 , so all of the material residing outside of the closed boundary defined by lines  177 ,  180 ,  193  and  179  would no longer be present. Although a substantial portion of the surface area of the blank  98  has been discarded, the remaining data present regarding the quality of the lens  178  is sufficient to indicate a miscalibration of the edging tool. The horizontal lines  194  and  195  are no longer present, but the horizontal line segments  104 ,  105  and  243  remain and are sufficient to readily indicate that the lens  178  is tilted with respect to the horizontal axis of the lens blank  98 . While only a portion of the horizontal line segment  103  is present on the lens  178 , a somewhat smaller part of the symmetrically positioned line segment  106  is visible. Vertical line  244  is slightly visible, while vertical line is not visible. This geometry indicates that lens  178  is off center. A hole  183  has been drilled in the lens  178 , but overlaps the circular marking  182 , indicating that the hole  183  has not been drilled in its desired location. The symmetrically placed circular marking  196  does not show any sign of a drilling operation, further indicating a substantial misalignment of the edging machine that performed the machining operations on the blank  98 . 
         [0071]    Referring also to  FIG. 29 , the lens blank  110  illustrated in  FIG. 24  is shown after being formed into a completed lens. In other words, the portion of blank  110  appearing in  FIG. 24  but absent in  FIG. 29  has been removed during the machining operation that formed the completed lens. The proper formation of the lens is apparent by observing that the vertical marking  153  is parallel to lens edge  185 , while lens edge  187  is parallel to vertical marking  155 . Similarly, horizontal lens edges  184  and  186  are parallel to horizontal markings  191  and  192 . The drilling operations also appear to be correct based on the presence of drilled bore  189  residing entirely within the circular marking  113 . A corresponding bore  190  appears within the boundary defined by the symmetrically spaced circular marking  188 . These correlations indicate that the edging device that removed material from the lens blank  110  has been properly calibrated and is performing as desired. 
         [0072]    The foregoing features embodied in the present invention are by way of example only. Those skilled in the lens manufacturing field will appreciate that the foregoing features may be modified as appropriate for various specific applications without departing from the scope of the claims. For example, the dimensions and shape of the collet  22  may be varied to accommodate a particular deblocking machine. Further, the position and number of blades  65  and  66  may be adjusted to accommodate a particular edging block  40 . Further, the calibration lenses  98  and  110  may have different shapes and dimensions that those depicted, and the surface markings may be varied as required for a particular lens design.