Abstract:
The concealing of one or more identification symbols into a target object and the subsequent determination or reading of such symbols through non-destructive testing is described. The symbols can be concealed in a manner so that they are not visible to the human eye and/or cannot be readily revealed to the human eye without damage or destruction of the target object. The identification symbols can be determined after concealment by e.g., the compilation of multiple X-ray images. As such, the present invention can also provide e.g., a deterrent to theft and the recovery of lost or stolen objects.

Description:
FEDERAL RESEARCH STATEMENT 
     This invention was made with Government support under Contract No. DE-AC09-08SR22470, awarded by the U.S. Department of Energy. The Government has certain rights in the invention. 
    
    
     FIELD OF THE INVENTION 
     The subject matter of the present disclosure relates generally to concealed identification symbols and to the nondestructive determination of the same. 
     BACKGROUND OF THE INVENTION 
     Conventionally, identification symbols have been used on a variety of objects to provide a positive identification of the object that can be used e.g., in theft recovery, loss recovery, inventory control, tagging, tracking, and other applications as well. For example, automobiles are commonly provided with vehicle identification numbers (VINs) located in view near a bottom edge of the front windshield. The VIN is useful e.g., in conveying title, tracking, insuring, recovery after theft, etc. Guns are also commonly provided with serial numbers that can be used for similar purposes. Many consumer devices are also provided with serial numbers for purposes that include warranty protection and theft recovery. 
     A common problem with conventional methods is that the identification symbols can be readily located and/or removed. In the case of a gun, for example, the serial number can be removed by grinding or filing the barrel at a position where the serial number is located. A VIN can also be removed, altered, or replaced. With consumer devices such as e.g., a television or appliance, removal of the serial number may be as simple as locating the rear of the device and removing a tag or plate. Of course, once the identification symbols are removed, positive identification of the device for recovery after a loss or theft may not be possible. In addition, the deterrent effect against theft is reduced where an identification symbol can be readily removed or altered. 
     Conventional methods, such as e.g., acid etching and magnetic particle testing, do exist for the recovery of identification symbols such as serial numbers where such were placed externally on metal surfaces that have been filed or ground. However, these methods typically only allow recovery of identification symbols that were created by engraving or stamping and where only shallow grinding or filing has been attempted for removal. These methods are usually ineffective against machined or laser etched surfaces that do not have deep metal deformation or against surfaces where deep destructive filing or grinding has occurred. 
     Accordingly, a method for concealing one or more identification symbols into an object would be useful to not allow simple non-invasive removal of the symbols without the destruction of the object or disassembly of the object and loss of its usefulness. Furthermore a method that can be used to read or determine such identification symbols without destroying the object would be particularly useful. An object or device incorporating concealed identification symbols that can be later determined (e.g., read or revealed) through nondestructive testing would also be useful. 
     BRIEF DESCRIPTION OF THE INVENTION 
     The present invention provides for concealing one or more identification symbols into a target object and for the subsequent determination of such symbols through non-destructive testing. The symbols can be concealed in a manner so that they are not visible to the human eye and/or cannot be readily revealed to the human eye without damage or destruction of the target object. The identification symbols can be determined after concealment by e.g., the compilation of multiple X-ray images. As such, in addition to identification, the present invention can also provide a deterrent to theft and assist in the recovery of lost or stolen articles. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
     In one exemplary aspect, the present invention provides methods of concealed identification. The methods include the steps of embedding one or more identification symbols into the target object such that the one or more identification symbols are not visible to the human eye from the outside of the object, cannot be revealed without disassembling the object, and cannot be identified using a single X-ray image. Additional steps of the method include obtaining multiple X-ray images of the one or more identification symbols in the object; applying one or more computed tomographic reconstruction algorithms to multiple X-ray images from the step of obtaining; and, determining the identification symbols from the step of embedding using the results of the step of applying reconstruction algorithms. 
     In another exemplary embodiment, the present invention provides a system for concealed identification. The system includes a target object with one or more identification symbols embedded into the target object. The one or more identification symbols are not visible to the human eye from the outside of the target object, cannot be revealed without disassembling the target object, and cannot be identified using a single X-ray image. 
     These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
         FIG. 1  provides an exploded perspective view of an exemplary device of the present invention in which a target object has been provided with multiple identification symbols. 
         FIG. 2  provides an assembled perspective view of the exemplary device of  FIG. 1 . The result of the assembly shows both visible and concealed identification symbols. 
         FIGS. 3 and 4  provide perspective views illustrating an exemplary method of the present invention. Vapor deposition can be utilized to provide higher contrast for non-destructive X-ray examination methods. 
         FIG. 5  provides a cross-sectional view of the exemplary embodiment of  FIG. 4  as taken along line  5 - 5 . 
         FIG. 6  provides a perspective view illustrating an additional exemplary embodiment for concealing identification symbols and another method of the present invention. 
         FIG. 7  illustrates an exploded perspective view of another exemplary embodiment and method of the present invention. 
         FIGS. 8-10  provide perspective views illustrating additional exemplary embodiments for concealing identification symbols and methods of the present invention. 
         FIG. 11  illustrates an exemplary method for determining concealed identification symbols of an exemplary embodiment of the present invention. 
         FIG. 12  depicts an exemplary embodiment of a target object of the present invention into which identification codes have been concealed and embedded. 
     
    
    
     The use of identical or similar reference numerals in different figures denotes identical or similar features. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
       FIG. 1  provides an exploded perspective view of an exemplary device of the present invention in which a target object  100  has been provided with multiple identification symbols  102  and  104 . Although shown in  FIG. 1  as numbers, the identification symbols could be alphanumeric symbols from any language, specially created characters, bar codes, and/or numerous other types of symbols that can be used for identification purposes. While multiple symbols are shown, a single symbol could be used as well. 
     Identification symbols  102  and  104  provide a system from which target object  100  can be positively identified. For example, identification symbols  102  and  104  may provide a unique code or identifier that is associated with target object  100 , which could be a variety of different articles, devices, machines, or sub-component thereof etc., for which concealed identification according to the present invention is desired. For example, identification symbols  104  could be a VIN for an automobile, a serial number for a weapon or consumer product, and other devices as well. Accordingly, the identification symbols  104  can be recorded or logged for later access. If, for example, target object  100  is lost or stolen and then later recovered, a record of the identification symbols  104  can be used to associate target object  100  with its rightful owner. 
     For the exemplary embodiment of  FIG. 1 , symbols  102  and  104  are constructed from a first component  106  and a second component  108 , which could be e.g., any two components of a device for which concealed identification is desired. Components  106  and  108  could be constructed from a variety of different materials such as e.g., metal, plastic, wood, and others depending upon e.g., the desired construction for target object  100 . For example, the target object  100  could be a gun where first component  106  is a steel barrel and second component  108  is the gun&#39;s receiver. Alternatively, the assembled target object  100  could be a sub-component of a larger device. Using the teachings disclosed herein, one of skill in the art will understand that the present invention may be applied to numerous other examples as well. 
       FIG. 2  provides a perspective view of the assembled state of the exemplary target object  100  of  FIG. 1 . More particularly, first component  106  has been inserted into the opening  110  of second component  108  to provide the assembled target object  100 , which may represent an entire device such as a gun (with barrel  106  inserted into receiver  108 ) or an assembled subcomponent of a larger device (such as two parts of the engine of an automobile). Regardless,  FIG. 2  illustrates a press fit (arrow P) assembly of two parts where an interference fit has been used to assemble the target object  100  and, at the same time, provide for concealing the identification symbols  104  in a permanent manner. By way of example, first component  106  could also be welded, glued or otherwise permanently affixed into the opening  100  of second component  108 . 
     As stated, once target object  100  is permanently assembled, identification symbols  104  are embedded within or behind second component  108  so that symbols  104  are concealed. Specifically, once assembled, identification symbols  104  are not visible to the human eye by simply viewing the outside of the object and cannot otherwise be determined by the naked human eye, if at all, without disassembling the target object  100  in a manner that disables and/or destroys target object  100 . 
     Additionally, identification symbols  104  cannot be determined through use of a single X-ray image due to low contrast. As shown, identification symbols  104  were placed on the curved outer surface  101  of first component  106  by e.g., engraving into surface  101 . As such, multiple X-ray images are required to determine identification symbols  104  once embedded within second component  108  as shown in  FIG. 2 . For example, multiple x-ray images must be taken about the cylindrical axis of first component  106 . Then, one or more algorithms or other processing steps must be applied to compile the images so as to provide a readable depiction of identification symbols  104 . For example, a tomographic reconstruction from multiple X-ray images may be undertaken. 
     The shape of components  106  and  108  shown in  FIGS. 1 and 2  are provided by way of example only. As will be understood using the teachings disclosed herein, numerous other shapes and configurations may be applied to embed and thereby conceal identification symbols according to the present invention. 
     Additionally, first component  106  is also provided with a decoy identification symbol  102 . As its name implies, decoy identification symbol  102  provides a ruse whereby e.g., a thief may believe that by removing symbol  102  all identifiers of target object  100  have been removed. Because the real identification symbols  104  are hidden from view, the thief is unaware that target object  100  can still be identified. Alternatively, identification symbol  102  could be used in conjunction with concealed identification symbols  104  to provide e.g., a two part code for identifying target object  100 . 
       FIGS. 3 and 4  provide perspective views illustrating another exemplary embodiment and method of the present invention. More particularly, in  FIG. 3  an applicator  105  is used to apply an X-ray contrasting agent  112  into an engraving of identification symbols  104  into the first plate  140 . The X-ray contrasting agent could be, for example, lead, tungsten, or another material having a high atomic number. These materials could be applied as a powder into the engraving in first plate  140 . As shown in the cross-sectional view of  FIG. 5 , the X-ray contrasting agent  112  fills the engravings and provides a more pronounced differentiation of X-ray image between steel and the contrasting agent than that of the image between steel and an air void. As such, during X-ray imaging of first plate  140 , the X-ray contrasting agent facilitates the determination or reading of symbols  104 . Although first plate  140  is shown as planar in  FIGS. 3-5 , a curved surface could be used as well. By way of additional example, the identification symbols  104  of the exemplary embodiment of  FIGS. 1 and 2  could be constructed with an X-ray contrasting agent as well. As shown in  FIG. 6 , first plate  140  could also be welded (arrows W) to another plate  142  so as to embed identification symbols  104 . The combined plates  140  and  142  can then be incorporated into a target object as a carrier of the identification symbols or the plates could form parts of the target object itself. 
       FIG. 7  illustrates another exemplary embodiment and method of the present invention in an exploded perspective view. In a manner similar to the embodiments of  FIGS. 1 and 2 , a target object  100  is assembled from a first component  106  and a second component  108  by a press fit into opening  110  and may also be welded, glued, or the like. Again, components  106  and  108  could be functioning parts of a target object  100  such as e.g., a gun, engine, or other device. For this embodiment, multiple identification symbols  104  are placed on a carrier  114  in different planes represented by faces  116 ,  118 ,  120  and reverse faces of carrier  114 . Symbols  104  may be placed by engraving and an X-ray contrasting agent  112  as described above may be employed as well. 
     The carrier  114  is embedded into target object  100  by being placed into opening  110  and then concealed by the permanent insertion of first component  106  thereafter. Although shown as a cube, carrier  114  may be constructed from a variety of different objects such as a cylinder, pyramid, and others. By placing the identification symbols  104  on multiple, non-parallel planes as shown in  FIG. 7 , a single X-ray image cannot be used subsequently to determine or reveal the identification symbols  104 . Instead, X-rays from multiple different angles corresponding to the different faces  116 ,  118 , and  120  are required. 
       FIG. 8  illustrates another exemplary embodiment and method of the present invention in which identification symbols  122  and  124  have been incorporated into a block  140  in different planes. The block may be fabricated using powder metallurgy or vapor deposition, such that identification symbols are embedded in the solid in an overlapping pattern. More specifically, a single X-ray generating source or device  126  is used to project the X-rays through  124  and  122  onto imaging plate  107  and the resulting image is not easily read. This configuration requires multiple X-ray images and computed tomography (CT) reconstruction. Next, the X-rays from device  126  pass through identification symbols  122  in a second plane onto imaging plate  107 —wherein the first plane and second plane of symbols  122  and  124  overlap and are adjacent and parallel to each other. As result, a three-dimensional code is created by the superimposed symbols  130 . The image on imaging plate  107  cannot be read with a single X-ray image or view but requires multiple images at differing angles reconstructed using computed tomography methodologies. 
     Another exemplary method of the present invention is illustrated in  FIG. 9 . For this embodiment, a first set of identification symbols  130  are positioned in a first plane such as a plate  134 , and a second set of identification symbols  132  are positioned in a second plane such as plate  136 . As shown, plates  134  and  136  are not coplanar or parallel to each other. Although shown as orthogonal to each other, plates  134  and  136  may positioned at other non-zero angles as well. By way of example, symbols  130  and  132  could be engraved, could be formed with an X-ray contrasting agent, could be deposited by vapor deposition, and/or other techniques could be used as well. 
     As also shown in the exemplary embodiment of  FIG. 9 , plates  134  and  136  are embedded into a target object  102  such that they are concealed from the human eye and cannot be so viewed without disassembly and/or destruction of target object  102 . Additionally, because the identification symbols  130  and  132  are positioned in different, non-parallel planes, by using an identification code that incorporates both symbols  130  and  132 , a single X-ray cannot be used to determine such a code once symbols  130  and  132  are embedded. Instead, as previously described, symbols  130  and  132  must be determined through multiple X-ray images taken at different angles to target object  102  and then compiled using one or more algorithms into a form whereby the symbols can be determined so that the identification code is revealed. 
       FIG. 10  illustrates another exemplary embodiment and method of the present invention in which identification symbols  144  and  146  are placed on non-parallel planes  156  and  158  of a first component  148  which is combined e.g., by welding (arrows W) or some other permanent technique with a second component  150  to create a target object  100 . Consequently, identification symbols  144  and  146  are embedded in target object  100 , are not visible to the unaided human eye and cannot be so viewed without disassembly and/or destruction of target object  100 . 
     A single X-ray cannot be used to reveal both sets of symbols  144  and  146 , which can be used together as a single identification code. Thus,  FIG. 11  illustrates schematically an example of using X-rays from multiple angles to determine identification symbols  144  and  146 . An X-ray source  165  is used to project X-rays  152  through first plane  156  to  162 , imaging plate, film, scintillator or the like, which in turn provides image  166  of identification symbols  144 . Similarly,  167 , the same X-ray source is repositioned or an additional X-ray source, is used to project X-rays  154  through first plane  158  to  160 , imaging plate, film, scintillator or the like, to reveal image  164  of identification symbols  146 .  FIG. 11  is provided by way of example only. Other techniques could be used as well. 
       FIG. 12  provides an exemplary embodiment of a gun  168  as a target object into which identification symbols  174  have been embedded onto the curved inner surface  172  of barrel  170 . As such, identification symbols  174  are hidden from viewing by the human eye unless the gun is destroyed by e.g., cutting the barrel  170  in half along its axis. Furthermore, a single X-ray cannot reveal symbols  174  because of their location on the curved inner surface of barrel  170  with low contrast requiring computed tomography to obtain the identification symbols.  FIG. 12  is provided by way of example only. Other target objects may be embedded with one or more identification symbols as previously described. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.