Abstract:
The invention described herein represents a significant improvement for the concealment of objects and people. The three-dimensional signature control architecture described herein uses an array of individual reflective pixels and an array of reflecting secondary mirrors in conic section. These two basic elements work in conjunction to collect electromagnetic energy, condense and segment it according to horizontal plane and original trajectory, collimate it, reflect it to along a parallel (to the original) trajectory, expand it, and emit it at an extension point of its original trajectory and in the same horizontal plane. An individual pixel consisting of a cylinder lens and a reflective concave mirror. The reflecting secondary mirrors forming a conic section of arrayed convex mirrors to receive light from pixels and reflect it to other pixels. The light which was incident on a first side of the object traveling at a series of respective trajectories is thus redirected and exits on at least one second side of the object according to its original incident trajectories. It captures and emits light which mimics trajectory, color, and intensity in many concurrent directions such that multiple concurrent observers, can “see through” the object to the background.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a Continuation-In-Part of application Ser. No. 09/757,053 filed Jan. 8, 2001, of Ser. No. 09/970,368 filed Oct. 2, 2001, and of Ser. No. 10/132,331 filed on Apr. 24, 2002. 
     
    
     
       BACKGROUND FIELD OF INVENTION  
         [0002]    The field of invention relates to three dimensional signature management or 3-D signature control technology (also known as cloaking) which has been described by the present inventor in related applications cross referenced in the present application. Some advantages can be gained from adapting these prior architectures to provide a system which passively conducts electromagnetic from multiple concurrent background perspectives and presents them to multiple concurrent observer positions as described in the related applications while omitting the need for a conductive fiber-optic or light pipe.  
           [0003]    This continuation in part describes a transmissive 3-D camouflaging architecture replaces the internal reflective means of the related applications (fiber optics or light pipes) with an external reflective means (mirrors in series).  
         BACKGROUND DESCRIPTION OF PRIOR INVENTION  
         [0004]    The concept of rendering objects invisible has long been contemplated in science fiction. Works such as  Star Trek  and  The Invisible Man  include means to render objects or people invisible. Prior Art illustrates the active camouflage approach used in U.S. Pat. No. 5,220,631. This approach is also described in “JPL New Technology report NPO-20706” August 2000. It uses an image recording camera on the first side of an object and a image display screen on the second (opposite) side of the object. This approach is adequate to cloak an object from one known observation point but is inadequate to cloak an object from multiple observation points simultaneously. In an effort to improve upon this, the prior art of U.S. Pat. No. 5,307,162 uses a curved image display screen to send an image of the cloaked object&#39;s background and multiple image recording cameras to receive the background image. All of the prior art uses one or more cameras which record two-dimensional pixels which are then displayed on screens which are themselves two-dimensional. These prior art systems are inadequate to render objects invisible from multiple observation points. Moreover, they are too cumbersome for practical deployment in the field.  
           [0005]    The process of collecting pictorial information in the form of two-dimensional pixels and replaying it on monitors has been brought to a very fine art over the past one hundred years. More recently, three-dimensional pictorial “bubbles” have been created using optics and computer software to enable users to “virtually travel” from within a virtual bubble. The user interface for these virtual bubble are nearly always presented on a two-dimensional screen, with the user navigating to different views on the screen. When presented in a three-dimensional user interface, the user is on the inside of the bubble with the image on the inside of the bubble&#39;s surface.  
           [0006]    Also known in the prior art are “three-dimensional” displays which attempt to display a first image stream to the right eye of observers and a second image stream to the left eye of observers. In actuality two streams can only achieve stereoscopic displays. Specifically, stereoscopic displays present the same two image streams to all multiple concurrent observers and are therefore not truly three-dimensional displays. The three-dimensional display as implemented using the technology disclosed herein provides many concurrent image streams such that multiple observers viewing the display from unique viewing perspectives each see unique image streams.  
           [0007]    Using concurrent image receiving three-dimensional “cameras” and image sending “displays”, the present invention creates a three-dimensional virtual image bubble on the outside surface of an actual three-dimensional object. By contrast, observers are on the outside of this three-dimensional bubble. This three-dimensional bubble renders the object within the bubble invisible to observers who can only “see through the object” and observe the object&#39;s background. The present invention can make military and police vehicles and operatives invisible against their background from nearly any viewing perspective. It can operate within and outside of the visible range.  
         BRIEF SUMMARY  
         [0008]    The invention described herein represents a significant improvement for the concealment of objects and people. Thousands of directionally segmented light receiving pixels and directionally segmented light sending pixels are affixed to the surface of the object to be concealed. Each receiving pixel segment receives colored light from one portion or trajectory of the background of the object. Each receiving pixel segment is positioned such that the trajectory of the light striking it determines the angles at which it is reflected such that it reemerges at the proper position and trajectory.  
           [0009]    The three-dimensional signature control architecture described herein uses an array of individual reflective pixels and an array of reflecting secondary mirrors in conic section. These two basic elements work in conjunction to collect electromagnetic energy, condense and segment it according to horizontal plane and original trajectory, reflect it to along a parallel (to the original) trajectory, expand it, and emit it at an extension point of its original trajectory in the same horizontal plane. An individual pixel consisting of a cylinder lens and a reflective concave mirror. The reflecting secondary mirrors forming a conic section of arrayed convex mirrors to receive light from receiving pixels and reflected it to sending pixels.  
           [0010]    Objects and Advantages  
           [0011]    Accordingly, several objects and advantages of the present invention are apparent. It is an object of the present invention to provide a three-dimensional receiver of light. It is an advantage of the present invention to provide a three-dimensional sender of light. It is an object of the present invention to provide an integration architecture to integrate the three-dimensional light receiver function together with the three-dimensional light sender function for passive concurrent real-time operation. It is an object of the present invention to create a three-dimensional virtual image bubble surrounding or on the surface of objects and people. Observers looking at this three-dimensional bubble from any viewing perspective are only able to see the background of the object through the bubble. This enables military vehicles and operatives to be more difficult to detect and may save lives in many instances. Likewise, police operatives operating within a bubble can be made difficult to detect by criminal suspects. The apparatus is designed to be always on. The apparatus is designed to consume no energy. It is rugged, reliable, and light weight. The lens structures can be made from transparent armor. It has relatively few parts. It efficiently redirects light with acceptable losses. It works across a wide range of polychromatic electromagnetic energy. Pixels are duplex, they both send and receive EM. The system does not need to know an enemy&#39;s position to be effective. The system conceals objects and people from multiple concurrent observers each located in different positions. No computer processor or electronics are required. It provides very high resolution.  
           [0012]    Further objects and advantages will become apparent from the enclosed figures and specifications. 
       
    
    
     DRAWING FIGURES  
       [0013]    [0013]FIG. 1 illustrates a single 3-D reflective pixel in top profile view.  
         [0014]    [0014]FIG. 2 illustrates a variety of cylinder lens designs for the single pixel of FIG. 1.  
         [0015]    [0015]FIG. 3 illustrates a pixel reflector&#39;s relationship with a first secondary reflector.  
         [0016]    [0016]FIG. 4 a  depicts front view of an array of reflective pixels.  
         [0017]    [0017]FIG. 4 b  illustrates a single column of 3-D reflective pixels.  
         [0018]    [0018]FIG. 5 illustrates a 3-D reflective pixel column&#39;s working relationship with some secondary reflectors.  
         [0019]    [0019]FIG. 6 illustrates a complete 3-D reflective pixel signature control apparatus and process of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0020]    [0020]FIG. 1 illustrates a single 3-D reflective pixel in profile view. The single pixel consists of two elements. The first pixel element being a cylinder lens  35 .  35 &#39;s focal length is equal to its diameter. The dimensions of the 3-D reflective pixel are variable heights greater or lesser than one inch are possible and operationally practicable. The following calculation describes of a non-gradient cylinder lens at one wavelength.  
           n 1/ s 1+ n 2/ s′ 1=( n 2− n 1)/ R 1  
         [0021]    set n1=1 (refractive index for air)  
         [0022]    set n2=1.5 (refractive index for a median wavelength)  
         [0023]    set s′1=2R1 (s′1 being the focal length caused by the first surface and R1 being the cylinder lens radius)  
         [0024]    set s1=infinity (object distance)  
         [0025]    Therefore, by substitution, the focal length (s′1) caused by the first surface equals 6 units and the radius (R1) equals 3 units. Thus incoming electromagnetic radiation with an object focus at infinity is brought to a focal point (by the first surface) just at the second surface of the cylinder lens. Affixed to the rear surface of  35  is a lenticular array  36 .  36  is manufactured from a material transparent in the wavelengths of interest and selected so as to minimize chromatic aberration within the system. These two lens elements thus forming a lens system which compresses the horizontal plane of incoming EM into a number of beams of outgoing EM which respectively reside in the same said horizontal planes.  
         [0026]    The second pixel element being a concave mirror  41  conic section with a forty five degree attitude. The mirror comprising a rigid material. The reflective surface of the  35  being on the side of the mirror adjacent to the  35 . Said conic section sharing an axis with the  35  such that all points on the reflective surface of the mirror reside at a forty five degree angle relative to rays emitted from the  35  at a normal to its ( 35   s ) surface. The  35  and the  41  being comprised of materials conducive to respectively refracting and reflecting desirable electromagnetic energy in the visible and/or non-visible wavelengths.  
         [0027]    [0027]FIG. 2 illustrates a variety of cylinder lens designs for the single pixel of FIG. 1. The  35  cylinder lens has no gradient refractive. It can be manufactured from transparent armor manufactured and molded by Simula Safety Systems of Phoenix, Ariz. Affixed to its rear surface is a calenderer plastic array of convex lenticular lenses  36   a . The  35  is manufactured such that its focal length (for a median wavelength) from the first surface is less than or equal to its diameter.  
         [0028]    A first alternate cylinder lens  35   a  has no gradient. It can be manufactured from transparent armor manufactured and molded by Simula Safety Systems of Phoenix, Ariz. Affixed to its rear surface is a calenderer plastic array of concave lenticular lenses  36   a . The  35   a  is manufactured such that its focal length (for a median wavelength) from the first surface is greater than its diameter.  
         [0029]    A second alternate cylinder lens  35   b  has no gradient. It can be manufactured from transparent armor manufactured and molded by Simula Safety Systems of Phoenix, Ariz. Affixed to its rear surface is a calenderer plastic array of concave, and convex lenticular lenses  36   b . The  35   b  is manufactured such that its focal length (for a median wavelength) from the first surface is equal to its diameter.  
         [0030]    A fourth alternate cylinder lens  35   d  has no gradient. It can be manufactured from transparent armor manufactured and molded by Simula Safety Systems of Phoenix, Ariz. It is manufactured such that its focal length (for a median wavelength) from the first surface is equal to its diameter. The equation listed under FIG. 1 describes the first surface of this lens.  
         [0031]    A third alternate cylinder lens  35   c  having a radial axis gradient (the refractive index varies according to position such that the highest refractive index is along the axis of the cylinder lens and the lowest refractive index is a cylinder closest to the surface of the cylinder lens). The  35   c  enables parallel rays in a horizontal plane to be compressed into a beam when the focal length from the first surface is approximately equal to its diameter. Gradient index cylinder lenses are suitable for this application because they can optimize performance across a range of wavelengths while minimizing chromatic aberration. Producers of gradient index lenses include Lightpath Technologies and Hikari Glass.  
         [0032]    [0032]FIG. 3 illustrates a pixel reflector&#39;s relationship with a first secondary reflector. The  41  single mirror having been described in FIG. 1. A first secondary mirror  61  comprises a conic section whereby the convex surface of said conic section is comprised of materials reflective in desired wavelengths. A vertical line (a line parallel to the center axis of the  61  conic section) drawn through any section of both the  61  and the  41  will subtend a forty five degree angle (with the respective reflective surface of each) which resides in the same plane as electromagnetic energy which passes through the axis of  35 .  
         [0033]    [0033]FIG. 4 a  depicts the front view of an array of reflective pixels.  35  being the front surface of a cylinder lens single reflective pixel of FIG. 1. Said single pixel being arrayed with and affixed to many similar reflective pixels to form a pixel array  81  covering the surface of an asset to be concealed.  
         [0034]    [0034]FIG. 4 b  illustrates a single column of 3-D reflective pixels  83  when viewed from the top and side. The  35  with  41  comprising one pixel and being affixed to a second reflective pixel cylinder lens  85  which is identical to  35 .  85  is connected to a second reflective pixel mirror  87  which is identical to  41 . Note that the  85  has an axis that is pushed back from that of  35 . Like wise the  87  is pushed back relative to  41 . Each lower tier is similarly backed off the higher layer&#39;s axis by a distance equal to the height of the  41 .  
         [0035]    [0035]FIG. 5 illustrates a 3-D reflective pixel column&#39;s working relationship with some secondary reflectors. The elements of FIG. 4 b  are present in addition to a second secondary reflector  93  and a third secondary reflector  95 .  93  and  95  being identical to  61 . Each of their axis residing in a circular conic section with a forty five degree slope.  
         [0036]    [0036]FIG. 6 illustrates a complete 3-D reflective pixel signature control apparatus and process of the present invention. The elements of FIG. 5 are shown integrated into a complete 3-D low observable casing which surrounds an asset  106 . Note that the asset is not to scale and that it would normally conform to the shape of the camouflage system (or vice versa). Also the asset would be affixed to the camouflage (or vice versa). An encompassing reflective pixel array  81  includes  35  and a third reflective pixel  102  as well as a fourth reflective pixel  107  and many other pixels. The  102 ,  107 , and  35  each being in the same horizontal plane. An assembled secondary mirror array  104  includes secondary mirrors  61 ,  93 , and  95  together with a number of other secondary mirrors to form a circular conic section with forty five degree slop  104 . The surfaces interior to the conic section having reflective properties in desired wavelengths. An electromagnetic absorbing patch  103  is shown. It is manufactured of a material that absorbs electromagnetic energy. In practice the  103  material is used to coat a number of surfaces that otherwise would reflect EM from undesirable trajectories. For example, material coats the surface (not shown) above the  104  and a surface (not shown) below  104 . The material also coats the non reflective sides of all the pixel mirrors. Additionally, the asset itself is coated with the  103  material.  
         [0037]    Operation of the Invention  
         [0038]    [0038]FIG. 1 illustrates a single 3-D reflective pixel in profile view. A first ray of polychromatic electromagnetic energy  31  is incident upon  35 . A second ray of polychromatic electromagnetic energy  37  is also incident upon  35 . Prior to incidence,  35  and  37  being on parallel trajectories and within the same horizontal plane.  35  compresses  31  and  37  along with all other parallel rays within the same horizontal plane  36  then collimates the light which becomes exiting first compressed beam  37   a .  37   a  resides in the same horizontal plane as  37  and has a parallel trajectory prior to being reflected by  41  to become vertical beam  39 . Similarly, a second trajectory of EM  47 , in a second horizontal plane is incident upon  35 , compressed by  35 , collimated by  36 , reflected vertically by  41  to become a second compressed vertical beam  57 . A third trajectory of EM  45  resides in the same plane as  47  but in a non-parallel trajectory. It and all other EM (incident upon  41 ) parallel to  45  and in its plane are compressed into a beam by  35 , collimated by  36 , and be reflected by  41  as a third compressed beam  55 . A horizontal plan of parallel trajectory EM  43  is in the same horizontal plane as  45  and  47  (but non-parallel in trajectory) similarly is incident upon  35 , and compressed to become a fourth compressed beam, collimated by  36 , which is reflected by  41  to become fourth vertical beam  53 . Note that the position of each beam&#39;s incidence upon  41  is a direct function of its original trajectory and its original horizontal plane. The system described effectively sorts and processes EM according to its original trajectory and horizontal plane. This is further described in FIG. 3, FIG. 5, and FIG. 6.  
         [0039]    [0039]FIG. 2 illustrates a variety of cylinder lens designs for the single pixel of FIG. 1. In a first cylinder lens embodiment,  47  and all parallel EM in its plane are incident upon  35 .  35  causes the EM to focus at its extreme rear edge. The EM is then collimated by  36 . The EM emerges from the  36  as narrow collimated beam of polychromatic EM  57 . The material of  35  and  36  being selected so as to perform achromatically.  57  is parallel to and in the same plane as  47 . Likewise  45  and other parallel rays within its plane are incident upon  35 .  35  compresses them and  36  collimates them into  55 .  55  is parallel to and in the same plane as  45 .  
         [0040]    [0040] 35   a  functions similarly to  35  except that the incident EM is not brought to a focal point within  35   a . Instead the EM is converging before it passes through  36   a  which causes the converging EM to expand into a collimated beam. The material of  35   a  and  36   a  being matched so as to provide achromatic performance.  35   b  has a back focal length equal to its diameter. The  36   b  has alternately both concave and convex lenticular surfaces such that a wider range of EM can be collimated. EM with a focal point within the  35   b  being collimated by the convex lenticular lenses and EM with a focal point outside of the  35   b  being collimated by the concave lenticular lenses.  
         [0041]    [0041] 35   c  is can be used to further enhance achromatic performance across a wider range of EM within the visible and outside of the visible. It has a gradient index and can be used in conjunction with  36 ,  36   a , or  36   b.    
         [0042]    [0042]FIG. 3 illustrates a pixel reflector&#39;s relationship with a first secondary reflector. P beam  63  leaves the  36  (not shown), is reflected by  41  to become vertical, and then is reflected by  61  to become horizontal again as P″ beam  73 . Note that  63 , and  73  are both in the same vertical plane and they are in parallel horizontal planes. Thus P″ retains its original trajectory information which was present in P. Three additional beams are shown which each share a horizontal plane but differ in trajectory. Note that X, Y, and Z are all incident on  41  in the same horizontal plane and incident upon  61  in a common elevated horizontal plane. The curvature of  61  causes X″, Y″, and Z″ to each respectively continue on trajectories parallel to X, Y, and Z respectively. Thus each collimated beam which emanates from a horizontal plane and that is emitted from  36  retains information relation to its horizontal plane and trajectory throughout the reflective pixel process of the present invention. Note that all arrows can be reversed and in practice EM is always being reflected by this mirror combination in many more planes and trajectories and in both directions.  
         [0043]    [0043]FIG. 4 b  illustrates a single column of 3-D reflective pixels. The  85  and  87  pixel is offset to enable EM incident upon  85  to pass vertically by  41  unencumbered. Likewise, each lower tier is offset form the one above it. At the middle of the array, the reverse is true. Thus EM is directed vertically upward unencumbered by the upper pixels and directed vertically downward unencumbered.  
         [0044]    [0044]FIG. 5 illustrates a 3-D reflective pixel column&#39;s working relationship with some secondary reflectors. As previously discussed,  47  EM is compressed and collimated by  35  and  36  and then reflected vertically upward as  57 . When  57  is incident upon  61 , it is directed at a trajectory parallel with  47  just as  55  is directed by  61  on a trajectory parallel with  45 . Thus two beam emanating from the single  35  pixel are directed by a secondary mirror  61  to two different secondary mirrors.  57  is then incident upon  95  which causes it to be reflected down into a reflective pixel (not shown) which spreads it out to be a first spread polychromatic beam  47   a .  47   a  being in the same horizontal plane as  47  and on a continuation of the  47  trajectory. Similarly,  55  is then incident upon  93  which causes it to be reflected down into a reflective pixel (not shown) which spreads it out to be a second spread polychromatic beam  45   a .  45   a  being in the same horizontal plane as  45  and on a continuation of the  45  trajectory. The  89  EM is incident upon lower pixel  85  as described in FIG. 4 b . Note that the collimated beams from  85  are incident upon the  61  in a higher plane that those from  35  but as they are reflected again, such as off of  93 , they are restored to the proper plane, such as third spread beam  89   a . This demonstrates that the horizontal plane information which is retained in this process is temporarily inverted during the reflected process then restored. A lower path for reflected light is also partially shown, if functions identically to the upper half and concurrently.  
         [0045]    [0045]FIG. 6 illustrates a complete 3-D reflective pixel signature control apparatus and process of the present invention. A C ray  101  enters the  35  pixel from a non-horizontal plane, it is collimated by  36  and reflected by  41  to be a non-vertical beam  101   a .  101   a  and many other EM which can not be concurrently processed by the present architecture must be absorbed when it is incident upon non-optical surfaces. As previously discussed material such as  103  absorbs the vast majority of such stray EM as it is incident on any non-optical surfaces.  47  enters the systems at  35 , is reflected vertically by  41  to become  57 , is reflected horizontally by  61 , is reflected vertically by  93 , is reflected horizontally by a pixel mirror connected to a first sending pixel  102 , the lens of  102  expanding the EM to become  45   a ,  45   a  being in the same horizontal plane and parallel in trajectory to  45 . Similarly,  45  enters the systems at  35 , is reflected vertically by  41  to become  55 , is reflected horizontally by  61 , to become  55   a , is reflected vertically by  95 , is reflected horizontally by a pixel mirror connected to a second sending pixel  107 , the lens of  107  expanding the EM to become  47   a ,  47   a  being in the same horizontal plane and parallel in trajectory to  47 .  
         [0046]    Note that all directions are reversible and in practice EM is always concurrently being received, reflected, and emitted by this assembly in many more horizontal planes and trajectories and in both directions than are represented herein.  
         [0047]    Conclusion, Ramifications, and Scope  
         [0048]    Thus the reader will see that the Three-Dimensional Signature Control Process and Apparatus With Military Application of this invention provides a highly functional and reliable means for using technology to conceal the presence of an object (or asset).  
         [0049]    While the above description describes many specifications, these should not be construed as limitations on the scope of the invention, but rather as an exemplification a preferred embodiment thereof. Many other variations are possible.  
         [0050]    The description describes a lens, mirror, mirror, mirror, mirror, lens architecture to transport electromagnetic energy from one side of an asset to another side. It is recognized that at least one of these mirrors can easily be eliminated. This may be desirable when a pyramid shaped asset is to be concealed. Eliminating a mirror requires mirror angles other than those specified herein.  
         [0051]    It is recognized that other lens and prism structures can intervene in combinations other than that specified herein.  
         [0052]    The specification describes a circular arrangement of pixels and secondary mirrors. Many other shapes are possible. No known constraints on the shapes of assets to be concealed exist.  
         [0053]    It is possible to substitute other lenses for the cylinder lenses, for example ball lenses or lenticular lenses. Also different combinations of lenses can be constructed to improve achromatic beam formation.  
         [0054]    The specification starts with an object light at infinity, other object focus lengths are possible and may at times be desirable.  
         [0055]    To achieve achromatic refraction, different lens combinations may be used in place of those specified herein.  
         [0056]    Lenses which enable wide angle light segmentation at the pixel level can be designed in many configurations and in series using multiple elements, shapes and gradient indices.