Interconnected lens materials arranged as lens sheets for improved camouflage

Abstract

To provide improved camouflage using a cost-effective method.SOLUTION: The present invention relates to uses of a lens sheet as camouflaging means in various applications. Various embodiments of a lens sheet assembly, methods of fabricating the various embodiments of the lens sheet assembly, and methods of using embodiments by placing the assembly between an object to be camouflaged and an observer are disclosed. Light from an object undergoes at least one of refraction and reflection such that the object is substantially disguised from an observer.SELECTED DRAWING: Figure 16

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to U.S. Patent Application No. 62 / 693,959, entitled "Improved Camouflage," filed July 4, 2018, the contents of which are incorporated herein in their entirety.

[0002] The present invention relates generally to enhanced camouflage, and in particular to the use of one or more sheets made from a plurality of interconnected lens materials arranged as a lens sheet, and various such combinations, to create enhanced camouflage. [Background technology]

[0003] As discussed above in Patent Application No. 62 / 693,959, entitled "Improved Camouflage," the concept of camouflage has been a subject of intense interest in practical human endeavors in a variety of fields requiring some form of concealment or privacy, such as art and entertainment, and in the study of wildlife biology and zoology. Aspects of camouflage, such as invisibility, have periodically captured the public imagination to great heights, as expressed, for example, in popular culture, literary fiction, science fiction, academic writing, and other forms of technical and artistic literature.

[0004] The study of camouflage has a surprisingly long history. The ancient Greek philosopher Aristotle recorded his observations of aquatic life in his book "The History of Animals," and particularly discussed the octopus's ability to use camouflage by changing its coloration to resemble its nearby surroundings. More recently, naturalist Abbott Thayer, in his well-known book entitled "Concealing-Coloration in the Animal Kingdom," put forward the controversial claim that all animal coloration has the evolutionary purpose of camouflage. Others have written similarly, either for or against these claims, and they have been advanced at various times.

[0005] Despite its long history, the study of various forms of camouflage is still an active and ongoing area of ​​research and development. Camouflage activities use many different methods and techniques that are often much more successful than simply blending a target object into its background. Color matching, countershading, and disruptive coloration are also camouflage techniques often first observed in wildlife biology.

[0006] When it comes to camouflage, a very popular topic among the general public is the concept of the invisibility cloak, which has been well represented in cultural media such as film and television, particularly those aimed at youth audiences. This has further helped motivate research into light and light-bending materials, as well as related research into the effective placement of optical devices to achieve the desired effect.

[0007] Many theoretical advances have been made in attempts to model how cloaking techniques approaching invisibility cloaks could work, primarily as a result of several papers that now provide a theoretical framework for an area of ​​research sometimes called transformation optics.

[0008] Although theoretical modeling related to transformation optics is relatively new, many materials that exhibit interesting optical properties, including reflection and refraction, are well known. However, the useful applications of these materials and the underlying principles governing their interaction with light are limited to a relatively narrow range of situations. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Patent Application Publication No. 2005 / 0286134 [Patent Document 2] U.S. Patent No. 8,411,363 [Patent Document 3] U.S. Patent Application Publication No. 2010 / 0326429 [Patent Document 4] U.S. Patent No. 7,235,736 [Patent Document 5] U.S. Patent No. 8,383,929 [Non-patent literature]

[0010] [Non-Patent Document 1] M. Bernardi, N. Ferralis, JH Wan, R. Villalon, and JC Grossman, Energy Environ. Sci., 2012, 5, 6880~6884 Summary of the Invention [Problem to be solved by the invention]

[0011] Practical realization of many of the ideas in transformation optics has been extremely difficult, in part because they require costly mechanisms, specialized materials called metamaterials, and other implementation difficulties. In contrast to the practical work of experimental researchers, authors of invisibility cloak technology have largely moved beyond speculation to its potential future uses. One of the goals of this invention is to provide improved camouflage using cost-effective techniques. [Means for solving the problem]

[0012] The present invention relates to the use of optical metamaterials as camouflage means in various applications. Some methods of using optical metamaterial sheets involve placing the metamaterial between an object to be camouflaged and an observer, whereby light coming from the object is one of refracted and reflected such that the object is substantially disguised from the observer.

[0013] Aspects of the present invention utilize the phenomenon of refraction and reflection of visible light and other waves in the electromagnetic spectrum through various arrangements of metamaterials or lenses and other optical materials to achieve desired effects in applications in architecture, art, entertainment, concealment, signature control, privacy, etc. Materials made from multiple lenses arranged in such a way as to refract and / or reflect visible light, near-infrared light, near-ultraviolet light, or other forms of light, or more broadly electromagnetic waves, are used to achieve desired artistic, concealment, or visual camouflage effects.

[0014] An example of such a material is a lens sheet, which can have a regular or semi-regular pattern of linear or non-linear lenses that can be combined with straight lines within the lenses to at least partially reflect or refract light away from a specific target or toward a desired area. Lenticular plastic sheeting is a translucent plastic sheet with one smooth side and the other made from small convex lenses called lenticules, which allow for the transformation of two-dimensional (2D) images into various optical illusions. Each lenticule acts as a magnifying glass to magnify and display a portion of the image below, i.e., the image on the smooth side.

[0015] Other materials that can be used include an array of small spherical lenses known as a fly's eye lens array, or a screen made up of many small convex lenses. Another example of a material that can be used is a linear or array prism sheet.

[0016] According to one aspect of the present invention, there is provided an apparatus and method for target concealment and shadow reduction that involves placing a double-sided lens sheet having lenses on both sides between a viewer and the target object to be concealed. The double-sided lens sheet can be constructed by adhering the smooth sides of a pair of single-sided lens sheets together back-to-back. In this embodiment, corresponding lenses on opposite sides of the double-sided lens sheet are arranged in a staggered manner with an offset relationship to one another. Light from the target that passes through the offset double-sided lens sheet is reflected and / or refracted in multiple directions, substantially reducing the visibility of the target object or the shadow cast by the target object.

[0017] According to another aspect of the present invention, there is provided an apparatus and method for target concealment and shadow reduction that involves placing a double-sided lens sheet having lenses on both sides between a viewer and the target object to be concealed. The double-sided lens sheet can be constructed by adhering a pair of single-sided lens sheets together, smooth side-to-side, back-to-back. In this embodiment, corresponding lenses on opposite sides of the double-sided lens sheet are aligned with each other. Light from the target that passes through the aligned double-sided lens sheets is reflected and / or refracted in multiple directions, substantially reducing the visibility of the target object or the shadow cast by the target object.

[0018] According to another aspect of the present invention, there is provided an apparatus and method for concealment and shadow reduction that involves disposing two double-sided lens sheets (a first double-sided lens sheet and a second double-sided lens sheet). As previously described, the double-sided lens sheet can be constructed by adhering a pair of single-sided lens sheets together, smooth sides facing back to back. Light from a target object passing through the two double-sided lens sheets is reflected and / or refracted in multiple directions, substantially reducing the visibility of the target object or shadows from the target object. In this embodiment, corresponding lenses on opposite sides of the first double-sided lens sheet are arranged in a staggered manner with an offset relationship to each other, while corresponding lenses on opposite sides of the second double-sided lens sheet are arranged side by side. This embodiment has the advantage of presenting a background scene behind the object to be concealed without creating a mirror image.

[0019] According to another aspect of the present invention, there is provided an apparatus and method for concealment and shadow reduction that involves the arrangement of two double-sided lens sheets (a first double-sided lens sheet and a second double-sided lens sheet). As previously described, the double-sided lens sheet can be constructed by adhering a pair of single-sided lens sheets together, smooth side-to-side, back-to-back. Light from a target object that passes through the two double-sided lens sheets is reflected and / or refracted in multiple directions, substantially reducing the visibility of the target object or shadows from the target object. In this embodiment, corresponding lenses on opposite sides of both the first double-sided lens sheet and the second double-sided lens sheet are aligned with each other. This embodiment also has the advantage of accurately presenting the background scene behind the object to be concealed without creating a mirror image.

[0020] In the drawings, embodiments of the present invention are shown by way of example only. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a schematic diagram illustrating the principles of the laws of refraction as they relate to visible light. FIG. [Figure 2]1 is a simplified schematic diagram of a lenticular lens sheet, partially in cross section; [Figure 3A] 1 is a simplified schematic diagram of a lens sheet positioned between a light source and a target. [Figure 3B] FIG. 10 is another simplified schematic diagram of a lens sheet positioned between a light source and a target, with the smooth sides of the sheet facing in opposite directions. [Figure 3C] 10 is yet another simplified schematic diagram of a lens sheet positioned between a light source and a target, with multiple lenses on either side of the sheet. [Figure 4] 4 is a simplified block diagram illustrating a variation of the embodiment of FIG. 3 in which a second lens sheet is positioned between the light source and the target. [Figure 5] FIG. 1 is a block diagram illustrating a lenticular lens used to simulate three-dimensional imaging. [Figure 6] FIG. 2 is a simplified perspective block diagram of a lens sheet placed in proximity to a target. [Figure 7] 3 is a plan view of the lens sheet of FIG. 2 surrounding a target. [Figure 8] FIG. 1 is a block diagram of a lens sheet made of several linear lenses positioned between a viewer and a target. [Figure 9] FIG. 9 is a block diagram of another arrangement similar to FIG. 8, in which the target has a horizontal profile. [Figure 10] A perspective view of a prism sheet made from several single-angle prism lenses. [Figure 11] 11 is a plan view of the prism sheet of FIG. 10 made from several single-angle prism lenses. [Figure 12] FIG. 1 is a schematic perspective view of a prism sheet made from several two-angle prism lenses. [Figure 13] FIG. 13 is a plan view of the prism sheet of FIG. [Figure 14] FIG. 1 is a simplified schematic diagram of a Dove prism lens sheet. [Figure 15]FIG. 1 is a simplified schematic diagram of an offset, double-sided lens sheet positioned between a target and an observer. [Figure 16] FIG. 1 is a simplified schematic diagram of an offset and aligned double-sided lens sheet positioned between a target and an observer. [Figure 17A] A simplified schematic diagram of the offset and aligned double-sided lens sheets of Figure 16 positioned between the target and the observer, but with an external offset between the two double-sided lens sheets. [Figure 17B] FIG. 17 is a simplified schematic diagram of the two offset double-sided lens sheets of FIG. 16 positioned between a target and an observer. [Figure 18] 1 is a simplified schematic diagram of two aligned double-sided lens sheets positioned between a target and an observer. [Figure 19] FIG. 19 is a simplified schematic diagram of the two aligned double-sided lens sheets of FIG. 18 with an external offset between the two double-sided lens sheets. [Figure 20] 1 is a schematic diagram of the concealment effect achieved by a double-sided lens sheet by blending portions of the background image together in a repeating pattern that creates neutral strips. [Figure 21] 1 is a schematic diagram of the concealment effect achieved by a double-sided lens sheet by blending portions of the background image together in a repeating pattern that creates neutral strips. [Figure 22] 1 is a schematic diagram of the concealment effect achieved by a double-sided lens sheet by blending portions of the background image together in a repeating pattern that creates neutral strips. [Figure 23a] 1 is a simplified schematic diagram in elevation of a single-sided lens sheet positioned between an observer and a background; FIG. [Figure 23b] 1 is a simplified schematic diagram in plan of a single-sided lens sheet positioned between an observer and a background; [Figure 24a] 1 is a simplified schematic diagram in elevation of a double-sided lens sheet positioned between an observer and a background; FIG. [Figure 24b] 1 is a simplified schematic diagram in plan of a double-sided lens sheet positioned between an observer and a background; FIG. [Figure 25a] FIG. 1 is a simplified schematic diagram in elevation of two double-sided lens sheets positioned between an observer and a background. [Figure 25b] 1 is a simplified schematic diagram in plan of two double-sided lens sheets positioned between an observer and a background. [Figure 26a] FIG. 1 is a simplified schematic diagram in elevation of a two-sided lens sheet positioned between an observer and a background, with the two sides having different LPIs. [Figure 26b] FIG. 1 is a simplified schematic diagram in plan of a double-sided lens sheet positioned between a viewer and a background, with the two sides having different LPIs. [Figure 27a] FIG. 10 is a simplified schematic diagram in elevation of another two-sided lens sheet positioned between a viewer and a background, the two sides having different LPIs. [Figure 27b] FIG. 10 is a simplified schematic diagram in plan of another double-sided lens sheet positioned between a viewer and a background, the two sides of which have different LPIs. [Figure 28a] FIG. 1 is a simplified schematic diagram in elevation of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. [Figure 28b] FIG. 1 is a simplified schematic diagram in plan of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. [Figure 29a] FIG. 1 is a simplified schematic diagram in elevation of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. [Figure 29b] FIG. 1 is a simplified schematic diagram in plan of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. [Figure 30a]FIG. 1 is a simplified schematic diagram in elevation of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. [Figure 30b] FIG. 1 is a simplified schematic diagram in plan of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. [Figure 31a] FIG. 1 is a simplified schematic diagram in elevation of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. [Figure 31b] FIG. 1 is a simplified schematic diagram in plan of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. [Figure 32] FIG. 1 is a simplified perspective view of a single-sided lens sheet that is vertically polarized so that the lenses are vertically arranged. [Figure 33] FIG. 33 is a simplified perspective view of the lens sheet of FIG. 32 depicting an image of an obscured background. [Figure 34] Background elevation view. [Figure 35] FIG. 1 is a simplified perspective view of a single-sided lens sheet having vertically polarized primary lenses and further having some angled sections of minor lenses whereby the minor lenses in the angled sections are arranged at an angle. [Figure 36] 36 is a simplified perspective view of the lens sheet of FIG. 35 depicting an image of a blurred background with different types of artifacts caused by corresponding angled areas. [Figure 37] FIG. 10 is another simplified perspective view of a single-sided lens sheet having vertically polarized primary lenses and further having some angled complex zones of minor lenses whereby the minor lenses in the angled complex zones are arranged at an angle. [Figure 38] 38 is a simplified perspective view of the lens sheet of FIG. 37 depicting an image of a blurred background with different types of artifacts caused by corresponding complex areas. [Figure 39] FIG. 1 is a simplified perspective view of a single-sided lens sheet having primary lenses of a first LPI and further having several zones of secondary lenses, whereby the primary lenses and secondary lenses extend vertically, but the secondary lenses in the zones are of a second angle / LPI different from the first LPI. [Figure 40] 40 is a simplified perspective view of the lens sheet of FIG. 39 depicting an image of a blurred background with different types of artifacts caused by corresponding areas. [Figure 41] FIG. 40 is a simplified elevational view of the lens sheet of FIG. 39 positioned in front of a background, illustrating improved concealment. [Figure 42] 1 is an image as viewed through two single-sided lens sheets offset a first distance from each other with the lenses disposed horizontally in each. [Figure 43] 10 is another image as viewed through two single-sided lens sheets offset a second distance relative to each other with the lenses disposed horizontally in each. [Figure 44a] Image through two single-sided lens sheets underwater, depicting the varying concealment depending on the offset between the two sheets. [Figure 44b] Image as seen through two single-sided lens sheets underwater, depicting varying concealment depending on the offset between the two sheets. [Figure 44c] Image as seen through two single-sided lens sheets underwater, depicting varying concealment depending on the offset between the two sheets. [Figure 45] A diagram depicting two lens sheets placed back to back, in which the target is partially visible at different oblique viewing locations and completely invisible at other viewing locations. [Figure 46] FIG. 1 is a schematic diagram of a riot shield having a transparent shield body and a lens sheet disposed thereon. [Figure 47]1 is a schematic diagram of an exemplary embodiment of an umbrella made from a lens sheet. [Figure 48] 1 is a schematic diagram of an exemplary embodiment of an umbrella made from a lens sheet. [Figure 49] 1 is a schematic diagram of an exemplary embodiment of an umbrella made from a lens sheet. [Figure 50] This is a video of a lens sheet used to avoid detection from the air. [Figure 51] This is a video of a lens sheet used to avoid detection from the air. [Figure 52] A video of an object that is protected from detection from the air. [Figure 53] 53 is an image of the object of FIG. 52 covered by a lens sheet to avoid detection from the air. [Figure 54] 54 is an image of the embodiment shown in FIG. 53 using military grade night vision equipment. [Figure 55] Footage of an object in the form of a quadcopter drone that utilizes a lens sheet to avoid detection during flight. [Figure 56a] 56 is a video of the object of FIG. 55 in the form of a quadcopter drone utilizing a lens sheet to avoid detection during flight. [Figure 56b] 56 is a video of the object of FIG. 55 in the form of a quadcopter drone utilizing a lens sheet to avoid detection during flight. [Figure 57a] FIG. 1 is a diagram of an object utilizing a cylindrical lens sheet to avoid detection. [Figure 57b] FIG. 1 is a diagram of an object utilizing a cylindrical lens sheet to avoid detection. [Figure 57c] FIG. 1 is a diagram of an object utilizing a cylindrical lens sheet to avoid detection. [Figure 57d] FIG. 1 is a diagram of an object utilizing a cylindrical lens sheet to avoid detection. [Figure 58a] FIG. 1 is a diagram of an elongated structure in the form of a mobile communications tower that uses a lens sheet to avoid viewing from the ground while still allowing viewing from overhead. [Figure 58b] FIG. 1 is a diagram of an elongated structure in the form of a mobile communications tower that uses a lens sheet to avoid viewing from the ground while still allowing viewing from overhead. [Figure 58c] FIG. 1 is a diagram of an elongated structure in the form of a mobile communications tower that uses a lens sheet to avoid viewing from the ground while still allowing viewing from overhead. [Figure 58d] FIG. 1 is a diagram of an elongated structure in the form of a mobile communications tower that uses a lens sheet to avoid viewing from the ground while still allowing viewing from overhead. [Figure 59a] 1 is an image of a chain link fence privacy insert made from an exemplary lens sheet of the present invention. [Figure 59b] 1 is an image of a chain link fence privacy insert made from an exemplary lens sheet of the present invention. [Figure 60] This is a video of a flexible lens sheet with holes similar to modern camouflage netting. [Figure 61a] FIG. 10 is a diagram of a strip of lens sheeting positioned on a net framework. [Figure 61b] FIG. 10 is a diagram of a strip of lens sheeting positioned on a net framework. [Figure 62] FIG. 10 is another view of the camouflage sheet with a matrix of holes in the netting framework designed to maintain the structural integrity of the sheet. [Figure 63] FIG. 1 is a diagram of a lens sheet with variable lens elements. [Figure 64] 1 is an image showing reduced reflection of light through a lens sheeting. [Figure 65] 1 is an image showing reduced reflection of light through a lens sheeting. [Figure 66] This is an image of an arcuate lens sheet used to conceal a target object. [Figure 67] This is an image of an arcuate lens sheet used to conceal a target object. [Figure 68]This is an image of an arcuate lens sheet used to conceal a target object. [Figure 69] This is an image of an arcuate lens sheet used to conceal a target object. [Figure 70] FIG. 1 is a diagram of a transparent corrugated material. [Figure 71] FIG. 10 is a diagram of another corrugated material design with the article acting as a lens with support structures. [Figure 72] 1 is a video of an exemplary aircraft hangar created using an exemplary lens sheet of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] In this description, a lens sheet is a translucent sheet made from an array of elongated lenses. These elongated lenses may be small convex lenses called lenticules that are often smooth on one side. In addition to lenticules, these elongated lenses also include prism lenses, Dove prism lenses, split Dove prism lenses (i.e., Dove prism lenses split in half lengthwise), single angle prism lenses, double angle prism lenses, and similar elongated lenses.

[0023] Lens sheets with elongated lenses, such as lenticules, on one side and a smooth flat surface on the opposite side are believed to have a variety of interesting visual effects.

[0024] In this disclosure, a single-sided lens sheet refers to a lens sheet having a plurality of elongated lenses, typically arranged substantially parallel, on one side and a smooth, typically flat, surface on the opposite side. The lenses may be lenticules, prismatic lenses, Dove prism lenses, split Dove prism lenses, or split prism lenses.

[0025] In this disclosure, a double-sided lens sheet refers to a lens sheet having a plurality of elongated lenses typically arranged substantially parallel on each side. Again, the lenses may be lenticules, prismatic lenses, Dove prism lenses, split Dove prism lenses, or split prism lenses. A double-sided lens sheet can be constructed by fastening or adhering the flat, smooth sides of a pair of single-sided lens sheets back-to-back, or by manufacturing a single sheet with lenses on both sides.

[0026] refraction It is commonly observed that a ray of light entering a material medium at an oblique angle changes its direction. This phenomenon is called refraction. Refraction generally involves a change in the direction of wave propagation due to a change in the propagation velocity. In the case of light, refraction can be traced to the deceleration of light as it enters the medium, the speed of light being its vacuum velocity c=3×10 8 It is slowed down from m / s to c / n, where n is the refractive index of the medium.

[0027] FIG. 1 depicts a diagram of the law of refraction, also known as Snell's law. An incident ray of light 106 travels from an initial point P1 through a first medium 102, such as air, and enters a second medium 104. The incident ray 106 is refracted at an interface 110, so that the trajectory of the refracted ray 108 arrives at point P2. This is explained by Fermat's principle of least time, which states that light travels from one point to another along a path that takes the least amount of time. The angle of incidence θ1 and the angle of refraction θ2 must be such that the optical path length from P1 to P2 is shortest. As shown in FIG. 1, the refractive indices of the first and second media are n1 and n2, respectively, so Snell's law states that n1 sin θ1 = n2 sin θ2.

[0028] As mentioned previously, materials made from a large number of lenses, subsets of which are arranged adjacent to or very close to one another in such a way as to refract visible, near-infrared, and / or near-ultraviolet light, are known. A typical example is a lens sheet. Lens sheets can be made from translucent plastic. Furthermore, some lens sheets can be smooth on one side, and the opposite side can be made from small convex lenses called lenticules. These lenticules can create two-dimensional (2D) views of otherwise normal scenes and can appear with a variety of interesting visual effects. For example, lenticules can act as magnifying glasses.

[0029] FIG. 2 is a schematic diagram of a cross section of a lenticular lens sheet. As shown, lenticular sheet 200 comprises multiple lenses or lenticules 202. Images from the lenticular lenses are viewed within a V-shaped viewing area corresponding to a viewing angle 204. The viewing angle 204 can be small or large. A small viewing angle 204 makes the image very sensitive to changes in the sense that a viewer only needs to rotate their head slightly to see a different set of images. For lenses with a wide viewing angle 204, a viewer can make a relatively large displacement or rotation of their head to see a different set of images, so that changes in the viewed image are not sensitive to displacements in head position or orientation. As a result, lenses with narrow viewing angles are good for three-dimensional (3D) effects, while lenses with wide viewing angles are good for dynamic impressions such as moving images, instantaneous changes, deformations, or zooming.

[0030] Development of lens array sheet Display devices that present a viewer with a three-dimensional image without the need for special glasses or other obstructions are sometimes called autostereoscopic. The first autostereoscopic method to emerge was the barrier technique, which involved dividing two or more images into stripes and lining them up behind a series of vertically arranged opaque bars of the same frequency. This was implemented in a painting by G.A. Bois-Clair, which appears to change from one image to another as the viewer walks by.

[0031] Later, physicist Gabriel M. Lippmann used an array of lenses on the imaging surface instead of an opaque barrier line, and was able to record a complete spatial image with parallax in all directions. The process utilized an array of small spherical lenses, known as a fly's eye lens array or monolithic lens array, to record and play back the image.

[0032] Several scientists have simplified the monolithic lens array by incorporating lenticular lens arrays. Lenticular lens sheets can be made from a linear array of thick plano-convex cylindrical lenses. Lens sheets are transparent or translucent and typically have a flat rear surface that forms the focal plane. Lens sheets are optically similar to parallax barrier screens.

[0033] Recently, there are specific lens designs for motion pictures, 3D large compositions, and mass production techniques.

[0034] Characteristics of lenticular sheets Conventional materials used to make lens sheets are made as transparent as possible while maintaining their ability to refract light. Higher material transparency is often desired, and in some applications, a clearer impression and better visual effects can be achieved with greater transmittance. The material should be stable enough to reduce thermally induced distortion so that the lenticular lens sheet can be used in many situations, such as when rolled up for shipping or use in a printing press. Lens sheets are typically made from one of acrylic, polycarbonate, polypropylene, PVC, and polystyrene. The lenses are arranged at an appropriate density, which can often be commonly measured and expressed as lenticules per inch, or lenses per inch (LPI).

[0035] A typical embodiment of these lens arrangements is depicted in FIG. 2, providing a V-shaped viewing area as discussed above. The sensitivity of the image to changes in the viewer's position depends on the viewing angle 204. A small viewing angle 204 makes the image sensitive to changes such that the viewer only needs to rotate their head slightly to see a different set of images. For wide-angle lenses 204, the viewer can rotate their head relatively far to see a different set of images, and therefore the changes are less sensitive. As a result, narrow viewing angle lenses are suitable for three-dimensional effects and dynamic impressions.

[0036] The material used to make the lenticular lens sheeting is preferably stable so that thermal distortion is reduced, while remaining flexible for use in a printing press.

[0037] Manufacturing Method Lenticular lens sheets are typically manufactured using machines or equipment specifically designed for this purpose. One such apparatus is described in Reference 1, the contents of which are hereby incorporated by reference in their entirety. This published application describes lenticular lenses and methods for manufacturing the lenses, specifically as lenticular lens webs, so that finishing operations such as cutting, lamination, and various end-use applications of the lenses, including labeling, can be accomplished or adapted to the manufacturing of the lens web. The publication also discloses a lenticular patterning device comprising a housing rotatable about a central longitudinal axis. The housing has an outer surface with a groove pattern. The groove pattern includes circumferentially and longitudinally extending grooves on the outer surface, the grooves having equal groove widths. The longitudinally extending grooves are substantially parallel to the central longitudinal axis, and the grooves cover the outer surface of the housing. The present invention also includes a method of using the lenticular patterning device to fabricate a lenticular lens web, which can be used to create a lenticular imaging web. The visual web can be used to create products such as wallpaper, banners, labels, etc.

[0038] Some embodiments of the present invention, described below, relate to the use of lens sheets to achieve improved camouflage. For example, one suitable type of lenticular lens sheet is described in Cited Document 2, the contents of which are incorporated herein by reference. This patent discloses a lenticular sheet including a first surface having at least two portions, a second, opposing surface, and a plurality of lenticular lenses formed on the first surface. Each portion of the first surface includes a number of lenticular lenses per centimeter that differs from the number of lenticular lenses per centimeter of an adjacent portion of the first surface.

[0039] Several materials can be used to make lens sheeting. These include polyethylene terephthalate (PET), which is not amorphous but retains its crystallinity. PET has good transparency, excellent gas barrier properties, and good resistance to oils, fats, and solvents. Polypropylene (PP) is also suitable if the article is completed by lamination or fabrication of a die-cut process. Polyvinyl chloride (PVC), made by combining ethylene, produced by refining petroleum, with chlorine derived from rock salt, can also be used. Generally, any translucent material, or even a transparent material such as glass, can be used to make such lens sheeting.

[0040] Specific applications and uses of various types of materials incorporating lenses, methods of making such materials, and articles of manufacture embodying such materials are described as exemplary embodiments of the invention.

[0041] Embodiment 1 - Shadow Reduction In an exemplary embodiment of the present invention, a material in the form of a lens sheet made from a plurality of linear lenticular lenses, which may be convex lenses, is utilized to reduce the shadow cast by a target object. The lenses are arranged to extend parallel to the target. Shadow reduction or elimination has several beneficial applications, including greenhouses, solar energy generation, architecture, visual mitigation, concealment, and signature management. Materials that convert solar energy into electrical energy, often deployed in or as roof tiles, can benefit from the exemplary shadow-reducing material of an embodiment of the present invention.

[0042] 3A depicts a simplified schematic diagram of an example embodiment. A light source 302 provides illumination to a sheet 306 of lenses 304, which may be lenticular lenses, positioned between the light source 302 and a target 310. Light rays 308 from the light source 302 pass through the lens sheet 306, and a subset of the light rays are refracted from the lenticular lenses 304 in multiple directions.

[0043] An incident ray 308 that may contribute to shadowing by target 310 is refracted by lens 304. Unlike the hypothetical unrefracted ray 308b, the refracted ray 312 does not directly illuminate target 310, thereby reducing and in some cases eliminating the shadow cast by target 310 from light source 302.

[0044] The bending and / or refraction of light can occur in all colors of the visible light spectrum, as well as in other non-visible portions of the electromagnetic spectrum, such as infrared and ultraviolet light.

[0045] In the depicted exemplary embodiment, the target 310 may be a person with a typical vertical profile, or other object with a height that is substantially greater than its width. In embodiments with such a vertically profiled target 310, the linear lenses 304 may be positioned to extend parallel to the height of the target 310. Thus, the linear lenses may be positioned in the same direction extending from head to toe of the target person.

[0046] In some embodiments, two or more lens sheets may be positioned either between the light source 302 and the target 310 or after the target 310. An anti-reflective layer, coating, mesh cover, textured surface, or other overlay may be required on the smooth surface facing away from the target object, and on the opposite side facing the target object.

[0047] Figure 3B depicts a simplified schematic diagram of an exemplary embodiment substantially similar to that depicted in Figure 3A, but with the lens sheet facing the opposite direction. Like elements are identified with like reference numerals in Figure 3B with an apostrophe (') appended to the reference numerals to distinguish them from their counterparts in Figure 3A. Thus, a light source 302' provides illumination to a sheet 306' of lenses 304', which may be lenticular lenses, positioned between the light source 302' and a target 310'. Light rays 308' from the light source 302' pass through the lens sheet 306', and a subset of the light rays are refracted in multiple directions from the lenticular lenses 304'.

[0048] An incident ray 308' that may contribute to shadowing by the target 310' is refracted by the lens 304'. Unlike the hypothetical unrefracted ray 308b', the refracted ray 312' does not directly illuminate the target 310', thereby reducing and in some cases eliminating the shadow cast by the target 310' from the light source 302'.

[0049] The bending and / or refraction of light can occur in all colors of the visible light spectrum, as well as in other non-visible portions of the electromagnetic spectrum, such as infrared. In the depicted exemplary embodiment, the target 310' may be a person with a typical vertical profile, i.e., having a height greater than its width. In an embodiment having such a vertically profiled target 310', the linear lenses 304' are positioned to extend parallel to the height of the target 310'. Thus, the linear lenses may be positioned in the same direction extending from head to toe of the target person.

[0050] An undesirable side effect of hiding foreground objects is that they obscure the background. To reduce background obscuration, embodiments of the present invention may utilize two linear lens sheets placed back-to-back with the same polarity. Alternatively, other embodiments use a single sheet manufactured with lenses on both sides that behave similarly to a Dove prism lens.

[0051] 3C depicts a double-sided linear lenticular sheet 1300 created by placing two linear lenticular sheets back-to-back with the same polarity. In this configuration, magnification of objects appears in the correct location. Beyond a certain distance d, objects viewed farther than location 1310 will appear as a mirror image. Objects viewed closer than location 1310 will appear in the correct orientation.

[0052] Because of the polarization of the sheeting, the effect is to reflect light ray 1304 by back-to-back lenses 1306 into reflected light ray 1308 such that reflected light ray 1308 converges at location 1310. Objects extending with the same polarity can thus be removed or reduced from the field of view, particularly in areas where the viewed object begins to appear as a mirror image. While FIG. 3C shows back-to-back lenses 1306 extending horizontally, lenses 1306 may extend vertically or at an angle and still achieve target concealment. In other embodiments, sheet 1300 including lenses 1306 can be curved to provide a larger target concealment area.

[0053] 4 depicts an exemplary simplified schematic diagram of another embodiment utilizing two or more sheets. As shown, a light source 402 provides illumination to a first sheet 406 of lenses 404 that is positioned between the light source 402 and a target 410. Light rays 408 from the light source 402 pass through the lens sheet 406, and a subset of the light rays are refracted from the lenticular lenses 404 in multiple directions.

[0054] A portion of the refracted light rays 412 may be refracted again by a second sheet 406' of lenses 404' positioned between the first sheet 406 and the target 410. In some embodiments, the first lens sheet 406 and the second lens sheet 406' as well as the lenses 404, 404' may be of substantially similar construction and optical properties.

[0055] Thus, light rays 412 refracted from the first sheet 406 pass through the second lens sheet 406' and are again refracted by the lenticular lens 404' in multiple directions in the plane of the lens 404', thereby reducing or eliminating shadows from the target 410.

[0056] In other embodiments (not explicitly shown), at least one lens sheet may be positioned near the target rather than between the light source and the target.

[0057] Embodiment 1.1 Solar tower, tubular or cylindrical solar cells In a related embodiment, lens sheets may be used to reduce shading on three-dimensional (3D) solar towers, where shading is known to substantially reduce the output of solar panels and, furthermore, due to their close placement, some towers may cast shadows on other nearby towers. Examples of such solar towers are described, for example, in "Solar Towers: A Guide to Solar Towers," ...

[0058] Examples of tubular or cylindrical solar cells are known. For example, Reference 3 describes a cylindrical solar cell. The cylindrical solar cell unit includes a substrate that is either tubular or solid rod-shaped, a back electrode circumferentially disposed on the substrate, a semiconductor junction layer circumferentially disposed on the back electrode, and a transparent conductive layer circumferentially disposed on the semiconductor junction. A transparent tubular housing is circumferentially disposed on the cylindrical solar cell. A first sealant cap is sealed to a first end of the transparent tubular housing. A second sealant cap is sealed to a second end of the transparent tubular housing. In some examples, the solar cell unit is an integrally integrated configuration of solar cells. In some examples, the solar cell unit is a solar cell.

[0059] Cited Document 4 describes a solar cell unit including a substrate, on which a plurality of photovoltaic cells are provided. The substrate has a first end and a second end. The plurality of photovoltaic cells arranged linearly on the substrate includes a first photovoltaic cell and a second photovoltaic cell. Each photovoltaic cell in the plurality of photovoltaic cells includes (i) a back electrode circumferentially arranged on the substrate, (ii) a semiconductor junction layer circumferentially arranged on the back electrode, and (iii) a transparent conductive layer circumferentially arranged on the semiconductor junction. The transparent conductive layer of a first photovoltaic cell in the plurality of photovoltaic cells is electrically connected in series with the back electrode of a second photovoltaic cell in the plurality of photovoltaic cells.

[0060] Reference 5 describes a non-planar photovoltaic module having a length comprising: (a) an elongated, non-planar substrate; and (b) a plurality of solar cells disposed on the elongated, non-planar substrate, each solar cell in the plurality of solar cells being defined by (i) a plurality of grooves around the non-planar photovoltaic module and (ii) a groove along the length of the photovoltaic module. In some embodiments, each groove in the plurality of grooves for the photovoltaic module independently has a repeating pattern, a non-repeating pattern, or is a spiral. In some embodiments, the module further comprises a patterned conductor providing serial electrical conduction between adjacent solar cells. In some embodiments, a portion of the patterned conductor providing serial electrical conduction between adjacent solar cells is within a groove in the plurality of grooves for the photovoltaic module.

[0061] Cylindrical solar panels can utilize thin-film solar panels wrapped around a series of tubes with a white paint underneath to reflect light that passes through the gaps between the tubes. A lens sheet or lens is positioned under the first layer of tubes. Thus, the first layer provides light refraction, allowing light to reach a second layer of tubes below the first layer. The first layer can also reflect light from the lenticular lens surface to the underside of the first layer, potentially allowing a third or fourth layer with a sheet or lens positioned between each layer of tubes to allow for greater output while using the same footprint. The above exemplary embodiment, as applied to a solar tower, is disclosed in a co-pending application filed with the assignee of the present invention entitled "System and Method of Amplifying Solar Panel Output," the contents of which are hereby incorporated by reference in their entirety.

[0062] In variations of the above embodiments, a linear prism sheet or an array prism sheet can also be used instead of the lens sheet. An array of small spherical lenses, known as a fly's eye lens array, can also be arranged on the screen. The screen therefore contains a large number of small convex lenses.

[0063] In another embodiment applied to solar thermal energy generation, mirrors are used to track the sun and reflect sunlight onto a central tower to produce steam that is used to generate electricity. The mirrors are positioned far apart so that shading from neighboring mirrors does not interfere with the light reflected onto the tower. This has the potential for shading reduction or elimination. The mirrors are positioned closer together, thereby generating more reflected light, thereby increasing the power output of the solar tower.

[0064] An anti-reflective film or coating on any of these lenses or sheets may be used to improve shadow reduction by allowing more light to pass through the lens or sheet.

[0065] Embodiment 2 - Light bending According to another embodiment of the present invention, a material having multiple lenses may be used to conceal or conceal at least a portion of the visible portion of a target object. Concealment is provided by utilizing the refraction of electromagnetic waves. Electromagnetic wave ranges include the visible light range, the shortwave infrared (SWIR) range, the near-infrared range, the near-ultraviolet range, and other ranges of the electromagnetic spectrum. The inventors have conducted experiments to determine that the material can provide concealment in the SWIR range, which is wavelengths from 0.9 μm to 1.7 μm (900 nm to 1700 nm), with regions having limits of 1.5 μm or 1500 nm typical of high-performance military night scopes. However, no limits could be established to the spectral range that the material can conceal at either end.

[0066] Unlike mid-wave infrared (MWIR) and long-wave infrared (LWIR) light, which are emitted by the object itself, SWIR is similar to visible light in that photons are reflected or absorbed by the object, providing the strong contrast needed for high-resolution imaging. Ambient starlight, background glow, or night light naturally emits SWIR, providing good illumination for outdoor nighttime imaging. Materials have been shown to bend and / or refract waves in the ultraviolet (UV), visible light (VIS), near-infrared (NIR), and SWIR ranges, thereby creating a concealment effect.

[0067] Advantageously, the material also blocks the transmission of thermal signatures or thermal radiation from targets hidden behind the material in the MWIR and LWIR ranges. Thermal radiation is electromagnetic radiation emitted from matter at temperatures above absolute zero, i.e., T > 0 Kelvin, T > -273.15°C, or any temperature T > -459.67°F.

[0068] When the material is not close enough to a target to gain heat from the target, it indicates the ambient temperature of the area around the material. When the material is positioned away from the target so as not to gain heat, it has been shown to block the transmission of a thermal signature from a target in the MWIR and LWIR ranges. In other words, while the material refracts electromagnetic waves in the UV, VIS, NIR, and SWIR ranges, when the material is positioned away from the target so as not to gain heat, it actually blocks the transmission of a thermal signature from a target in the MWIR and LWIR ranges.

[0069] This is important because modern night vision devices often combine NIR or SWIR with thermal signatures, known militarily as "fused night vision" devices. Fusion night vision devices are very difficult to counter with current technology, but exemplary materials of embodiments of the present invention can conceal targets from detection by fused night vision devices. The thermal spectrum is blocked, thereby hiding the target's thermal signature behind the exemplary material.

[0070] The lenses in the material may be convex lenses, lenticular lenses, or other types of lenses arranged in an appropriate manner to refract light as described below. The use of materials to conceal at least a portion of an object from an observer has many applications. As will be appreciated by those skilled in the art, this property has beneficial uses including architecture, art, entertainment, visual mitigation, concealment, and signature management.

[0071] As mentioned above, in addition to shadow reduction, lenticular lenses, or sheets of lenticular lenses, can be used to conceal objects from the viewer.

[0072] Embodiment 2.1 - Emulated 3D Images Lenticular lenses can also be used to create simulated three-dimensional images of specially printed images that appear to be positioned behind and in contact with the rear surface of the sheeting. Although the image is not physically displayed directly behind the sheeting, the lens creates an optical effect or optical illusion for the viewer that the image appears to be behind the lens or sheeting.

[0073] Figure 5 depicts a configuration used to create a display with a simulated three-dimensional effect. A lens sheet 530 made of several lenticular lenses 534 with a viewing angle 538 is used to create a display with a simulated 3D effect. The lenticular lenses 534 receive light from a special printed image 532, which may be positioned immediately behind and adjacent to the smooth rear side 536 of the sheet 530, as shown in the exemplary embodiment depicted in Figure 5.

[0074] Embodiment 2.2 - Concealment using a flat sheet By positioning one or more lenticular sheets in front of or around a target relative to a viewer, the image or signature of the target object can be dramatically reduced or even eliminated with an appropriate separation distance between the target and the lenticular sheets, which can be calculated or computed taking into account the type of lens used, the angle of the lens, and the frequency of the lens, which is typically specified per square inch.

[0075] When the sheet is flat and placed between the target and the viewer, the effect is refraction. The lenses direct light from behind either side of the target object. If the target is far enough away from the lenticular sheet, only a minimal signature is sensed or an image is observed. By moving the target object further back, or by moving the lenticular sheet closer to the viewer, the signature from the target can be eliminated entirely, effectively achieving concealment or nearly achieving invisibility.

[0076] 6 depicts a simplified schematic diagram of an exemplary embodiment of the present invention. Light rays from a target 602 pass through a sheet 606 of lenses 604 positioned between a viewer 610 and the target 602. As the light rays from the target 602 pass through the lens sheet 606, they are refracted in multiple directions by the lenticular lenses 604. The refracted light rays 609 help conceal the target 602 by creating blind spots 603, thereby reducing, and in some cases eliminating, the image of the target 602 from the viewer 610's view.

[0077] Embodiment 2.3 - Concealment using a curved sheet When the lens sheet is curved around a target, the optical effect demonstrated is the bending of light around the target, or the refraction / dispersion of light from the target inside, which mimics the bending of light around the target as perceived by an observer looking from the outside of the cylinder.

[0078] 7 depicts a plan view of a simplified block diagram of a lens sheet curved around a target 710 into a cylindrical wall 714. The cylindrical wall 714 may be formed by rolling a large lenticular sheet of lenticular lenses into the shape of a cylinder of radius R.

[0079] The center of the cylindrical wall 714 is positioned at an appropriate separation distance D between the eyes of the observer 702 (not drawn to scale) and the target 710 to effectively conceal or substantially reduce the visibility of the target 710. The target 710 is positioned away from the cylindrical wall 714 in the center of the cylindrically shaped sheet.

[0080] The path traversed by incident light ray 712 can be seen in Figure 7. Because the sheet is curved around the target 710, the effect is to effectively bend (e.g., using refraction / dispersion) the light around the target 710. The refraction, reflection, and dispersion of light ray 708 inside the wall 714 mimics the bending of light around the target 710 as perceived by an observer 702 looking from outside the cylindrical wall 714.

[0081] The inventors have found that if the target is outside on the side of the cylinder opposite the viewer, there will be an area near the cylinder where the target cannot be seen.

[0082] Embodiment 2.4 - Concealing an object with a vertical contour Figure 8 depicts a lens sheet 802 made from several linear lenses 804 positioned between a viewer 808 and a target 810. The lenticular lenses 804 have a length that extends in the Y direction, the same as the target 810, i.e., a person standing along the Y direction. The lens sheet 802, as depicted, lies in the XY plane. Using an arrangement such as that depicted in Figure 8, refracted light rays 806 hide the target 810 from the viewer 808.

[0083] As mentioned above, if the target 810 has a vertical profile, i.e., a height along the Y direction that is greater than its width along the X direction, then the linear lenses should extend along the same Y direction to improve concealment. This is shown in the contrasting situation depicted in Figure 9.

[0084] Figure 9 shows another arrangement similar to Figure 8, but where the target 910 has a horizontal profile. As shown, a lens sheet 902 made of several linear lenses 904 is positioned between a viewer 908 and the target 910. The linear lenses 904 have a length extending in the Y direction, but the target 910, i.e., the vehicle, has a width along the X direction that is greater than its height in the Y direction.

[0085] Lens sheet 902, as depicted, lies in the XY plane. Using an arrangement such as that depicted in Figure 9, refracted light rays 906 may not be able to completely conceal target 910 from viewer 908, as image 912 may still be visible. To better conceal target 910 that has a width greater than its height, lens sheet 902 can be rotated so that the lenticular lenses extend horizontally.

[0086] Embodiment 2.5 - Prism Sheet In other embodiments, a similar effect of removing a target from the scene can be achieved with a bi-angle or single-angle prism sheet. Figure 10 depicts a prism sheet 1000 made from several single-angle prism lenses 1002. The prism lenses are angled orthogonally at one angle 1004.

[0087] Figure 11 depicts a top view of the prismatic sheet 1000 of Figure 10 made from several single-angle prismatic lenses 1002. The prismatic lenses are angled at right angles, as shown at angle 1004. The refraction of light rays 1102 helps to conceal or hide a target 1106 from an observer 1108. A second set of lenses at an opposite angle can follow to the right to hide the target 1106 in the center of the sheet 1000.

[0088] In yet another embodiment, a similar effect of removing objects from the scene can be achieved with a two-angle prism sheet. Figure 12 depicts a prism sheet 1200 made from several two-angle prism lenses 1202. Unlike Figures 10 or 11, there are no right angles in the prism lenses.

[0089] Figure 13 depicts a plan view of the prism sheet 1200 of Figure 12. As can be seen, the prism sheet 1200 is made up of several two-angle prism lenses 1202. The prism sheet 1200 is positioned between an observer 1208 and a target 1210.

[0090] The refraction of light ray 1206 as depicted helps to conceal or hide target 1210 from observer 1208. The trajectories of other light rays 1204 that are not refracted remain unchanged and therefore do not contribute to or interfere with the concealment of target 1210.

[0091] Embodiment 2.6 - Linear lens sheet with back-to-back contact As mentioned earlier, an undesirable side effect of hiding foreground objects is that they obscure the background. To reduce background obscuration, embodiments of the present invention may utilize Dove prism lenses.

[0092] 14 depicts a Dove prism lens sheet 1400 with a viewer at location 1402 viewing an object at a distance from lens sheet 1400. A target object positioned between sheet 1400 and location 1410 will appear in the correct orientation to the viewer at location 1402. However, objects farther from sheet 1400 than location 1410 will appear as a mirror image.

[0093] Because of the polarization of the sheeting, the effect is to reflect light ray 1404 by prism 1406 into reflected light ray 1408 such that reflected light ray 1408 converges at location 1410. Objects extending with the same polarity can therefore be eliminated or reduced from the field of view, particularly around areas farther away from lens sheeting 1400 than location 1410, where the objects seen begin to appear as mirror images.

[0094] Negative refraction is an abnormal bending of light that does not normally occur in nature. Materials with negative permittivity and permeability are known to have a negative refractive index. Such materials have recently been constructed in the form of metamaterials, i.e., periodic resonant electromagnetic structures on a scale smaller than the wavelength, and act as homogeneous optical media. Ray optical components such as lenses can be miniaturized and arranged periodically. Simple combinations of such periodic arrangements can be used, but these are not metamaterials. Metamaterials affect the passing light waves as if they were inhomogeneous media. However, metamaterials can affect light rays like homogeneous media. In this sense, metamaterials can be regarded as ray optical metamaterials.

[0095] Embodiment 2.7 - Offset double-sided lens sheet FIG. 15 depicts an exemplary offset double-sided lens sheet 1500 of an embodiment of the present invention. An exemplary method of target concealment and shadow reduction using the embodiment of FIG. 15 involves positioning a double-sided lens sheet 1500 having lenticular lenses on both sides thereof between a viewer and a target object to be concealed.

[0096] In the embodiment of FIG. 15, it can be seen that the corresponding lenses (such as lens 1512 and lens 1514) on the opposite sides of the double-sided lens sheet 1500 are arranged in a staggered manner having an offset relationship with each other. The offset distance is depicted as Δx in FIG. 15. The offset distance Δx can be in the range of 0 < Δx < H, where H is the height of the lenticular lens as shown in FIG. 15 (or the diameter if the lens is semi-cylindrical).

[0097] Light rays from a target object passing through the double-sided lens sheet 1500 are refracted in a number of directions with the effect of substantial reduction in the visibility of the target object and the shadow of the target object.

[0098] In this arrangement, an object at a particular distance d will appear as a mirror image when viewed beyond location 1510. Because of the polarization of the sheet, the effect is to reflect the light rays off multiple back-to-back lenses 1506, 1507 so that they converge at location 1510 along with other similarly reflected light rays.

[0099] One way to correct for the mirror image is to place double-sided lenses adjacent to lens sheet 1500. Such an arrangement is shown in Figures 16, 17, 18, and 19. The offset will shift the background view to the left or right if the lenses are extended vertically.

[0100] In the embodiments of Figures 3C, 14, and 15, the target will appear in a mirror image if the target is further away, i.e., to the right beyond locations 1310, 1410, or 1510, respectively.

[0101] As can be seen, focal location 1510 is at a different location than focal location 1310' corresponding to the embodiment of Figure 3C in which the lenses are not offset but are in-line. It is noted that focal location 1310' and focal location 1510, although at different locations, remain in the same or substantially the same plane parallel to lens sheet 1500 and at the same distance d from the location of lens sheet 1500.

[0102] The focal point 1510 can be controlled by the offset distance Δx. As will be explained later, the particular method of making the double-sided lens sheet (e.g., adding water between two single-sided lens sheets) can relatively easily vary the offset distance Δx, which allows adaptation of the described embodiments in a particular context depending on the distance d and other factors.

[0103] Thus, objects with the same polarity, specifically objects seen in the area around location 1510, may be eliminated or reduced in visibility. While FIG. 15 shows lenses 1506 extending horizontally, as will be understood by those skilled in the art, lenses 1506 may extend vertically or at an angle and still achieve target concealment. In other embodiments, a sheet similar to sheet 1500 including multiple lenses 1506 may be curved to create a larger target concealment area. This offset provides the ability to shift the background and target to the left or right when the lens polarity is vertical, and if the shift is large enough, the target is removed from view.

[0104] Embodiment 2.8 - Offset and aligned double-sided lens sheets Figure 16 shows two closely spaced double-sided lens sheets, depicted as first and second sheets 1600A and 1600B (collectively sheets 1600) according to an exemplary embodiment of the present invention. A method of target concealment and shadow reduction using the embodiment of Figure 16 involves positioning these two double-sided lens sheets 1600, each having lenses on both sides, between a viewer and the target object to be concealed.

[0105] 16, it can be seen that corresponding lenses (e.g., lens 1612 and lens 1614) on opposite sides of offset double-sided lens sheet 1600A are arranged in a staggered manner with an offset relationship to one another, whereas corresponding lenses on opposite sides of second double-sided lens sheet 1600B are arranged side-by-side with one another.

[0106] Thus, corresponding lenses on opposite sides of a double-sided lens sheet 1600B in a line are the same distance to the top or bottom of the sheet. Of course, in vertically polarized embodiments where the lenses are vertically arranged, corresponding vertical lenses on either side of a double-sided lens sheet in a line will be at the same level or height to the left or right of the sheet.

[0107] This embodiment has the advantage of accurately presenting the background scene behind the object being concealed without creating a mirror image. Light rays from the target object passing through the offset double-sided lens sheet 1600A and the aligned double-sided lens sheet 1600B are refracted and / or reflected at angles that substantially reduce the visibility of the target object or the shadowing of the target object.

[0108] In this arrangement, in contrast to the embodiment of Figure 3C, an object at a particular distance d does not appear in a mirror image when viewed at location 1610. Because of the polarization of the lenses in sheet 1600, the effect is to reflect light rays into reflected rays by lenses 1606, 1607 that are offset, unlike the embodiment of Figure 3C where the lenses are in line.

[0109] Objects of any polarity can be eliminated or reduced in visibility by shifting angles to remove the object (and surrounding background) from view, or by utilizing neutral areas, objects of the same polarity can be reduced or eliminated from the views discussed in Figures 20, 21, and 22. Objects of the opposite polarity can also be eliminated or reduced in visibility if the width of the object can be hidden in these neutral areas.

[0110] 16 shows lenses 1606, 1607 extending horizontally, the lenses may extend vertically or at an angle and still achieve target concealment. In other embodiments, a sheet similar to lens sheet 1600 may be curved to provide a larger target concealment area.

[0111] Embodiment 2.9 - External offset between offset and aligned lens sheets Figure 17A shows two closely spaced double-sided lens sheets, depicted as first and second sheets 1700A and 1700B (collectively sheets 1700), exemplary of another embodiment of the present invention. A method of target concealment and shadow reduction using the embodiment of Figure 17A involves positioning these two double-sided lens sheets 1700, each having lenses on both sides, between a viewer and the target object to be concealed. This embodiment has been found to have the same effect as the embodiment of Figure 16.

[0112] 17A, it can be seen that corresponding lenses (e.g., lenses 1706 and 1707) on opposite sides of offset double-sided lens sheet 1700A are arranged in a staggered manner with an offset relationship to one another, whereas corresponding lenses on opposite sides of second double-sided lens sheet 1700B are arranged side-by-side with one another.

[0113] Thus, corresponding lenses 1714, 1715 in each double-sided lens sheet 1700A, 1700B are at different distances from a common bottom and are therefore externally offset or staggered. Of course, in vertically polarized embodiments in which the lenses are vertically arranged, corresponding vertical lenses on either side of a single double-sided lens sheet will be at the same level or height to the left or right of the sheet.

[0114] This embodiment has the advantage of accurately presenting the background scene behind the object being concealed without creating a mirror image.

[0115] Light rays from a target object passing through the offset double-sided lens sheet 1700A and the aligned double-sided lens sheet 1700B are refracted and / or reflected at angles that substantially reduce the visibility of the target object or the shadowing of the target object.

[0116] 3C embodiment, object 1702 at a particular distance d does not appear in a mirror image when viewed at location 1710. Because of the polarization and placement of sheets 1700A, 1700B, the effect is to reflect or refract light rays by multiple back-to-back lenses 1706, 1707 so that object 1702 is observed in the correct orientation.

[0117] Objects of any polarity can be eliminated or reduced in visibility by shifting angles to remove the object (and surrounding background) from view, or by utilizing neutral areas; objects of the same polarity can be reduced or eliminated from the scene, as discussed with reference to FIGS. 20, 21, and 22. Objects of the opposite polarity can also be eliminated or reduced in visibility if the object's width can be hidden in these neutral areas. While FIG. 17 shows multiple lenses 1706, 1707 extending horizontally, the multiple lenses may extend vertically or at an angle and still achieve target concealment. In other embodiments, a sheet similar to sheet 1700 including multiple lenses may be curved to provide a larger target concealment area.

[0118] The embodiment of FIG. 17A has been found to have similar effectiveness to the embodiment of FIG. 16, even though in the embodiment of FIG. 17A corresponding lenses 1714, 1715 of lens sheets 1700A, 1700B, respectively, are in an externally offset relationship.

[0119] FIG. 17B illustrates two closely spaced double-sided lens sheets, depicted as first and second sheets 1700C and 1700D (collectively, sheets 1700′), in accordance with another embodiment of the present invention. The embodiment of FIG. 17B is similar to the embodiment of FIG. 17A, except that both double-sided lens sheets 1700C, 1700D have corresponding lenses on opposite sides that are arranged in an offset relationship. That is, in the embodiment of FIG. 17B, it can be seen that corresponding lenses on opposite sides of sheets 1700C, 1700D (e.g., lenses 1706′ and 1707′) are arranged in a staggered manner with an offset relationship to one another. This is in contrast to the embodiment of FIG. 17A, in which only sheet 1700A has an offset relationship, while sheet 1700B has a linear arrangement.

[0120] A method of target concealment and shadow reduction using the embodiment of Figure 17B involves positioning two of these double-sided lens sheets 1700', each having lenses on both sides, between the viewer and the target object to be concealed. This embodiment has been found to have the same effect as the embodiment of Figure 16.

[0121] Corresponding lenses 1714', 1715' in each of double-sided lens sheets 1700C, 1700D can be different distances from a common bottom and thus can be externally offset or staggered. Of course, in vertically polarized embodiments where the lenses are vertically arranged, corresponding vertical lenses on either side of a single double-sided lens sheet will be at the same level or height to the left or right of the sheet.

[0122] This embodiment also has the advantage of accurately presenting the background scene behind the concealed object without creating a mirror image.

[0123] Light rays from a target object passing through the offset double-sided lens sheets 1700C, 1700D are refracted and / or reflected in multiple directions, substantially reducing the visibility of the target object or the shading of the target object.

[0124] 3C , object 1702′ at a particular distance d does not appear in a mirror image when viewed at location 1710′. Because of the polarization and placement of sheets 1700C, 1700D, the effect is to reflect or refract light rays by multiple back-to-back lenses 1706′, 1707′ so that object 1702′ is observed in the correct orientation.

[0125] Embodiment 2.10 - Two aligned double-sided lens sheets Figure 18 shows two closely spaced double-sided lens sheets, depicted as first and second sheets 1800A and 1800B (collectively, sheets 1800), exemplary of another embodiment of the present invention. A method of target concealment and shadow reduction using the embodiment of Figure 18 involves positioning these two double-sided lens sheets 1800, each having lenses on both sides, between a viewer and the target object to be concealed. This embodiment has also been found to have similar effectiveness to the embodiment of Figure 16, but at different angles.

[0126] In the embodiment of Figure 18, it can be seen that corresponding lenses (e.g., lens 1812 and lens 1814) on opposite sides of offset double-sided lens sheet 1800A are aligned with no external offset. Corresponding lenses on opposite sides of double-sided lens sheet 1800A, 1800B are aligned with each other.

[0127] Thus, corresponding lenses on opposite sides of a double-sided lens sheet 1800A, 1800B in a row are the same distance to the top or bottom of the sheeting. Of course, in vertically polarized embodiments where the lenses are vertically arranged, corresponding vertical lenses on either side of a double-sided lens sheet in a row will be at the same level or height to the left or right of the sheeting.

[0128] This embodiment has the advantage of accurately presenting the background scene behind the object being concealed without creating a mirror image.

[0129] In this arrangement, in contrast to the embodiment of Figure 3C, an object 1802 at a particular distance d does not appear in a mirror image when viewed at location 1810. Because of the polarization of sheets 1800A, 1800B, the effect is to reflect or refract light rays by multiple back-to-back lenses 1806, 1807 so that object 1802 is observed in the correct orientation.

[0130] Objects of the same polarity can be eliminated or reduced in visibility by utilizing neutral areas, as discussed with reference to FIGS. 20, 21, and 22. Objects of opposite polarity can also be eliminated or reduced in visibility if the width of the object can be hidden in these neutral areas. While FIG. 18 shows multiple lenses 1806, 1807 extending horizontally, the multiple lenses may extend vertically or at an angle and still achieve target concealment. In other embodiments, a sheet similar to sheet 1800 including multiple lenses may be curved to provide a larger target concealment area.

[0131] The embodiment of Figure 18 has been found to have a similar effect to the embodiment of Figure 16 at different angles, even though in the embodiment of Figure 18 corresponding lenses 1814, 1815 of lens sheets 1800A, 1800B, respectively, are in an externally offset relationship.

[0132] Embodiment 2.11 - Two aligned double-sided lens sheets with external offset Figure 19 shows two closely spaced double-sided lens sheets, depicted as first and second sheets 1900A and 1900B (collectively, sheets 1900), exemplary of another embodiment of the present invention. A method of target concealment and shadow reduction using the embodiment of Figure 19 involves positioning these two double-sided lens sheets 1900, each having lenses on both sides, between a viewer and the target object to be concealed. This embodiment has also been found to have the same effect as the embodiment of Figure 16, but at a different angle.

[0133] In the embodiment of FIG. 19, it can be seen that the double-sided lens sheets 1900A, 1900B have an external offset, ie, they are offset so that corresponding lenses (eg, lens 1915 and lens 1914) are not aligned.

[0134] Corresponding lenses on opposite sides of the same lens sheet 1900A (or within lens sheet 1900B) are the same distance to the top or bottom of the sheet. Of course, in vertically polarized embodiments where the lenses are vertically arranged, corresponding vertical lenses on either side of a double-sided lens sheet in a row will be at the same level or height to the left or right of the sheet.

[0135] This embodiment also has the advantage of accurately presenting the background scene behind the concealed object without creating a mirror image.

[0136] In this arrangement, in contrast to the embodiment of Figure 3C, an object 1902 at a particular distance d does not appear in a mirror image when viewed at location 1910. Because of the polarization of sheets 1900A, 1900B, the effect is to reflect or refract light rays by multiple back-to-back lenses 1906, 1907 so that object 1902 is observed in the correct orientation.

[0137] Objects of the same polarity can be eliminated or reduced in visibility by utilizing neutral areas, as discussed with reference to Figures 20, 21, and 22. Objects of opposite polarity can also be eliminated or reduced in visibility if the width of the object can be hidden in these neutral areas. While Figure 19 shows multiple lenses 1906, 1907 extending horizontally, the multiple lenses may extend vertically or at an angle and still achieve target concealment. In other embodiments, a sheet similar to sheet 1900 including multiple lenses may be curved to provide a larger target concealment area.

[0138] The embodiment of Figure 19 has been found to have a similar effect to the embodiment of Figure 16 at different angles, even though in the embodiment of Figure 19 corresponding lenses 1914, 1915 of lens sheets 1900A, 1900B, respectively, are in an externally offset relationship.

[0139] When functioning, all of the embodiments depicted in Figures 3C, 14, 15, 16, 17A, 17B, 18, and 19 can be characterized by their ability to produce a fused, repeating image from the viewer's perspective.

[0140] An example is shown in Figure 20. A lens sheet 2002 is placed between the viewer and a background scene 2010 depicting a flagpole 2006. The image viewed through the sheet 2002 is created by blending together repeated portions of the background scene 2010. The flagpole 2006 is not visible in the expected location within the viewed image created from multiple neutral areas 2004 and repeated areas 2008.

[0141] To achieve this repeating pattern, in one particular embodiment, two different types of lenses are used back-to-back in sheeting 2002, where the lenticules have different viewing angles, one with forty-two degrees (42°) and the other with thirty degrees (30°). The viewing angles are shown conceptually in FIG.

[0142] Lenticules arranged in this manner create a series of overlapping or repeating sub-images, each with a slightly different perspective of the same background. The repeating sub-images merge at locations approximately one or two inches wide, creating fuzzy displays made up of the left and right sides of the visible image, identified in Figure 20 as neutral areas 2004. These neutral areas 2004 are blended regions of the left and right portions of these repeating sub-images.

[0143] Target objects in the neutral zone 2004 are hidden from view. This is more clearly shown in FIGS.

[0144] FIG. 21 depicts a lens sheet 2102 made from one or two double-sided lens sheets placed between a background scene 2106 and the viewer. The lenticular lenses used are of the same LPI and viewing angle on each side. The image viewed through the sheet 2102 is formed by blending together portions of the background scene 2106. The viewed image includes a neutral zone 2104. When a target object such as a hand is brought very close to the lens sheet 2102, it becomes partially visible as an image 2108 of the hand. However, as depicted in FIG. 22, when the hand is moved away from the lens sheet, the hand is hidden in the neutral zone 2204.

[0145] 22 depicts a lens sheet 2202 positioned between a background scene 2206 and a viewer. The image viewed through the sheet 2202 is formed by blending together portions of the background scene 2206. The viewed image includes a neutral area 2204, where a target object (e.g., a hand) is kept away from the lens sheet 2202 and is therefore hidden within the neutral area 2204.

[0146] The material of lens sheet 2202 does not need to be offset to achieve these repeated partial images, and thus a similar effect of repeating partial images can be achieved using the embodiments depicted in Figures 16, 17A, 18, or 19.

[0147] It should be noted that in conjunction with the embodiments of Figures 3C, 14, 15, 16, 17, 18 and 19, the depictions of Figures 20-22 (in which the partial images are repeated vertically) are best understood as overhead views.

[0148] Otherwise, in embodiments where the lenses are positioned horizontally, these partial images would instead be repeated horizontally on top of one another, so that, for example, the sky in one partial image would be shown below the ground in an adjacent partial image.

[0149] Many version variations of the above embodiments in specific subcombinations are discussed below.

[0150] Version 1 Figures 23a-b are simplified schematic diagrams in elevation and plan view, respectively, of a single-sided lens sheet positioned between an observer and a background, where the background is obscured.

[0151] Version 2 Figures 24a-b are simplified schematic diagrams in elevation and plan view, respectively, of a double-sided lens sheet positioned between an observer and a background, the background viewed through which has a mirror image orientation and is also sensitive to observer movement.

[0152] Version 3 Figures 25a-b are simplified schematic diagrams in elevation and plan view, respectively, of two double-sided lens sheets positioned between an observer and a background, the background viewed through which also has the correct orientation and accommodates the observer's movements.

[0153] Version 4 26a-26b are simplified schematic diagrams in elevation and plan views, respectively, of a double-sided lens sheet positioned between a viewer and a background, with the two sides having different LPIs. The larger lenses (e.g., 75 LPI) are closer to the target, and the smaller lenses (100 LPI) are closer to the viewer. The image seen is of a mirror image orientation, but has a wider field of view than the lens sheet of FIGS. 24a-24b.

[0154] Version 5 27a-27b are simplified schematic diagrams in elevation and plan views, respectively, of another double-sided lens sheet positioned between a viewer and a background, with the two sides having different LPIs. The larger lenses (e.g., 75 LPI) are closer to the viewer, and the smaller lenses (100 LPI) are closer to the target. This view in this embodiment is correctly oriented but is characterized by a smaller field of view than in FIGS. 25a-25b and is sensitive to viewer movement. This version can be curved toward the viewer to offset multiple image artifacts. If the viewer gets too close to the lens sheet, the image wall snaps back to the correct orientation as the viewer enters the convergence zone of the light rays on the viewer's side of the lens sheet.

[0155] Version 6 Figures 28a-28b are simplified schematic diagrams in elevation and plan views, respectively, of two double-sided lenticular sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. This is equivalent to two of the embodiments in Figures 26a-26b positioned close to each other. The lenses of each sheet on the viewer's side can be smaller (e.g., 100 LPI), while the lenses of each sheet on the background or target side can be larger (e.g., 75 LPI). The background viewed through this lenticular sheeting also has the correct orientation and accommodates the viewer's movement.

[0156] Version 7 29a-29b are simplified schematic diagrams in elevation and plan views, respectively, of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPIs. This is equivalent to two of the embodiments in Version 5 positioned close to each other. The lenses of each sheet on the viewer's side can be larger (e.g., 75 LPI), while the lenses of each sheet on the background or target side can be smaller (e.g., 100 LPI). With this Version's correct orientation, the correct viewpoint can be achieved without multiple image artifacts.

[0157] Version 8 30a-30b are simplified schematic diagrams in elevation and plan views, respectively, of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPI. The outer lenses are smaller (e.g., 100 LPI) and the inner lenses are larger (e.g., 75 LPI). This version displays mirror image orientation and can display multiple images. This version cannot be curved to cancel mirror image or multiple (repeating) artifacts.

[0158] Version 9 31a-31b are simplified schematic diagrams in elevation and plan views, respectively, of two double-sided lens sheets positioned between a viewer and a background, with the two sides of each sheet having different LPI. The inner lenses are smaller (e.g., 100 LPI) and the outer lenses are larger (e.g., 75 LPI). This version can display multiple images. This version cannot be curved to offset multiple image artifacts, but it does exhibit correct image orientation.

[0159] Primary and secondary lens configuration In addition to the embodiments depicted above, other exemplary embodiments of the present invention comprise lens sheets with areas having lenses of different polarity, angle, or LPI. The term "minor lens" is used to refer to any portion of a lens that differs from the LPI, wide / narrow angle, and / or overall angle / polarity of the primary lens, as shown in Figure 32. All of the lenses mentioned can be manufactured as a single piece.

[0160] Lens sheets can be manufactured with different polarities within the same lens sheet, even for single sided lens sheets, as depicted in Figures 32-41.

[0161] Although the secondary lenses are shown slightly off-horizontal in some of the exemplary embodiments, any other angle and / or different sized lenses of different shapes may be used to mimic camouflage.

[0162] Because background color adaptation with static camouflage is nearly impossible due to variable locations, environments, seasons, and times of day, these embodiments allow the material to adapt to the background color as any of the variables change.

[0163] 32 is a simplified perspective view of a single-sided lens sheet 3200 that is vertically polarized and therefore has vertically arranged lenses. These lenses may be referred to as elemental lenses.

[0164] When a background image is viewed through the lens sheet 3200 of Figure 32, the resulting viewed image may appear as shown in Figure 33, which depicts an image of a fuzzy background. The actual background is shown in Figure 34.

[0165] Version 10 FIG. 35 is a simplified perspective view of a single-sided lens sheet 3500 (referred to herein as version 10) having vertically polarized primary lenses and further having several angled sections 3502 of secondary lenses whereby the secondary lenses within the angled sections are arranged at one or different angles.

[0166] Thus, Figure 35 shows a single-sided lenticular lens of a base lens in vertical polarization with two different angles for the minor lenses at different geometries. In the depicted embodiment, one angle of the minor lenses in area 3502 is slightly left of vertical and appears about halfway down the shape, while the other angle is slightly right of vertical. This can often be painstakingly done with some difficulty after the manufacturing process. Advantageously, the manufacturing process is easier during production when the lens material is molded from a drum, whereby the molds all result in different lens angles.

[0167] Figure 36 is a simplified perspective view of the lens sheet 3500 of Figure 35 depicting an image of an obscured background with different types of artifacts caused by corresponding angled areas 3502. This has a similar effect to camouflage to disperse the background so the lens material is not perceived as distinctive by the viewer. Unlike static camouflage where the color is predetermined, an added benefit of this embodiment is that all lenses are dynamically created from the surrounding color of the background.

[0168] Version 11 Figure 37 is another simplified perspective view of a single-sided lens sheet 3700 (referred to herein as Version 11) that has vertically polarized primary lenses and further has several angled complex zones 3702 of secondary lenses whereby the secondary lenses in the angled complex zones are arranged at an angle. This embodiment better represents a more natural geometry for use in outdoor forest settings. While a single angle is used for the arrangement of secondary lenses in zone 3702 about the pattern, two or more angles may be used to increase realism. Lens sheets other than single-sided lens sheets may also be utilized.

[0169] Figure 38 is a simplified perspective view of the lens sheet of Figure 37 depicting an image of an obscured background with different types of artifacts caused by corresponding complex areas, showing how a specially manufactured lens sheet 3700 represents the background. This has a similar effect to camouflage to disperse the background, so the material does not appear unique to the viewer. Unlike static camouflage where the color is predetermined, an added benefit here is that all lenses still attract the surrounding color of the background.

[0170] Version 12 Figure 39 is a simplified perspective view of a single-sided lens sheet 3900 (referred to herein as Version 12) having primary lenses of a first characteristic (e.g., first LPI) and further having several zones of secondary lenses. Both the primary lenses and secondary lenses are vertically arranged, but the secondary lenses in the zones have a second characteristic (e.g., second LPI) that is different from the first characteristic (e.g., the second LPI is different from the first LPI). By taking advantage of the difference between the different LPIs, a similar effect to an angled arrangement of secondary lenses is achieved.

[0171] In Figure 39, the first feature for the primary lens can be a narrow angle and the second feature for the secondary lens can be a wide angle lens with the same LPI. Conversely, the first feature for the primary lens can be a wide angle and the second feature for the secondary lens can be a narrow angle lens with the same LPI. Again, by taking advantage of the difference between the narrow and wide angle lenses with the same LPI, the same or similar effect as an angled placement of the secondary lens can be achieved.

[0172] As mentioned above, the secondary lens may be of a different LPI or angle from the primary lens. There may be two or more secondary lenses with different LPI and / or different angles.

[0173] FIG. 40 is a simplified perspective view of the lens sheet of FIG. 39 depicting an image of a blurred background with different types of artifacts caused by corresponding areas.

[0174] Figure 41 is a simplified elevational view of the lens sheet of Figure 39 positioned in front of a background, illustrating improved concealment. The simulated depiction of the lens sheet of Figure 39 against the background is depicted vertically in black for polarity illustration only. Such lines are not perceptible to the viewer, and the embodiment provides improved concealment.

[0175] The pattern used in the secondary lens to break up the background may be specific to the environment. For an urban environment, angles that depict walls, floors, or stairs may be used. For a dry desert, sparse breakups that lead to such an environment are used. For a snowy environment, a pattern that mimics shapes found in a snowy environment is used.

[0176] The fabrication of different patterns within lenticular lenses is known, and this embodiment can be made using known fabrication techniques. While known fabrication techniques use lens material directly on top of the image, this embodiment of the present invention depicts the background and hides the target.

[0177] Embodiment 3.1 Making a two-sided lens sheet (permanent bonding) As previously described, the two-sided lens sheet can be constructed from a pair of single-sided lens sheets. The two-sided lens sheet can be constructed by bringing the back sides together and permanently or temporarily bonding, adhering, or attaching the smooth sides of the pair of single-sided lens sheets together. Also, in some embodiments described later, temporary bonding elements are added between the smooth surfaces or flat surfaces of each single-sided lens sheet to improve the visibility of the two-sided lens sheet.

[0178] Embodiment 3.2 Making a two-sided lens sheet (adding water) In a variation of the above method of constructing a two-sided lens sheet, the inventor has found that adding water between the smooth sides of a pair of single-sided lenticular lenses creates a suitable temporary or movable bond. The water creates a suitable bond that allows movement of the two single-sided lens sheets relative to each other with some opposing pressure. Advantageously, the added water has been found to improve transparency when viewing the background through the two-sided lens sheet.

[0179] A further second advantage of adding water between the two lens sheets is that the water enables adjustment of the offset distance Δx as described with reference to FIG. 15. Thus this feature can convert or change a two-sided lens sheet that is in a single row without an offset (offset distance Δx = 0) to a two-sided lens sheet with an offset (0 < Δx < H), and vice versa.

[0180] Adding water further has the advantage of providing the ability to easily change the angle between the two lenticular sheets to generate a resonance wave pattern that further splits the viewing of the target using the two lenticular sheets. While this technique functions above water, underwater the refraction of the water may cancel or negate the effect of the refraction of the lens, and it may be a requirement to hide the target underwater.

[0181] Version 13 Figures 42 and 43 depict two images from two single-sided lens sheets, with both lenses extending horizontally from left to right. By varying the angle off-center as shown in Figure 42, it can be seen that the interference pattern between the two single-sided lens sheets creates a large disruptive element vertically. The embodiment of the lens sheet arrangement depicted in Figures 42-45 is referred to herein as Version 13. By varying the angle of the upper article even further off-center, the interference pattern becomes much tighter in comparison as shown in Figure 43.

[0182] A single lens sheet on the surface of water has the ability to conceal a diver below. However, when the lens sheet is submerged, it allows a viewer to see through to the diver below. The refraction of light in water changes the angle of light that the lens can refract. An object can still be concealed in the same way with a single lens described herein or any other method as it is above water, but the distance between the concealing target and the lens may be longer underwater due to the extra refractive factor of water on the light beam. This also applies to the reduction of shadows created by an underwater target and a light source in or above the water, where the lens is between the light source and the target.

[0183] In other embodiments, the two lens sheets can be positioned back-to-back, back-to-back, or face-to-face with the same polarity (left to right), and both can be submerged. By adjusting the angle between the two lens sheets, different concealment or camouflage effects can be observed using interference patterns such as those shown in Figures 44a, 44b, and 44c. When polarized light converges, a target diver can be seen through the lens sheet material of both articles. Distorting the view to an extent that the viewer cannot identify the target can be highly beneficial.

[0184] Varying the distortion, for example based on the degree of offset between the lens sheets, can produce very different results, for example the image shown in Figure 44c does not resemble the outline or shape of a person.

[0185] In yet another embodiment, depicted in Figure 45, the use of two lens sheets 4502, 4504 of the same polarity is used back-to-back, but with a slight angular offset between the two sheets. This causes the target 4506 to be partially visible at different viewing angles of the viewer 4508 and invisible at other angles. Determining what the target 4506 is can be difficult at the best of times. Distortion can also interfere with accurately aiming at the target 4506.

[0186] Embodiment 3.3: Creating a double-sided lens sheet (a single, integrated product) In other embodiments, the double sided lens sheeting may be integrally constructed or manufactured as a single piece, which may have advantages in durability and strength during use.

[0187] While both lens sheets 2300, 2400 in Figures 23a and 24a utilize the same type of material, they have different effects on the trajectories of light rays, resulting in different obscuring of targets. Lens sheet 2300 refracts light, which creates a blind spot in the center where targets can be located and almost completely hidden from viewers on the other side. In low density backgrounds, this works very well; in high density backgrounds with lots of detail, it creates a smudge that runs either horizontally or vertically, depending on the lens orientation, which can make the material stand out against the background and draw attention.

[0188] The lens sheet 2400 of Figure 24a overcomes this drawback by still removing the target from the viewer on the opposite side while providing some of the shape and more detail in the background in the lens sheet 2400, but the image of the background is a mirror image.

[0189] Lens sheet 2500 of Figure 25a corrects the mirror image imperfections of lens sheet 2400 by simply using a second lens sheet 2400 in front of or behind the first lens sheet to correct the orientation. There will be some degradation in image quality between lens sheet 2400 and lens sheet 2500, most of which can be improved in manufacturing.

[0190] Although lens sheet 2400 is shown as one item, it could be two separate single-sided lenses joined together with the smooth sides of the lenses. This also applies to the material in lens sheet 2500, which is simply two lens sheets 2400 in front of each other.

[0191] In Figure 25a, lens sheet 2500 can exhibit distortions such as ripples due to loose gaps between the pair of individual single-sided lens sheets (similar to lens sheet 2400) that make it up. Bonding the individual lens sheets can be used to prevent or reduce ripples.

[0192] Lens sheet 2500, compared to lens sheet 2400 (mirror image), allows for the correct orientation, proper shape, and correct viewer as the viewer moves around. However, objects that are hidden from the viewer are now visible through lens sheet 2500. There are two solutions to this problem. The first solution is to offset one of the two double-sided lens sheets as shown in Figures 16, 17a, or 17b. That is, one of the two single-sided lens sheets that make up one of the double-sided lens sheets is offset relative to each other. This shifts the image to the right or left, allowing the target object to be removed from the viewer's field of view.

[0193] Depending on the lens configuration, the LPI (lenses per inch) and lens angle, the target can be hidden in different ways with either lens sheet 2400, 2500. This can be done by adjusting the offset, moving the lens to the left or right of the second lens in lens sheet 2400. Note that in areas where an image of the target object is present, there is instead a blurred image of the background. This occurs when the material blends in the right and left portions of the visible background, which is why you see half a tree in the left portion of the material. This image will repeat in the material depending on the LPI and angle. This allows the hidden object to be placed in a neutral blended area.

[0194] While lens sheet 2400 can utilize the instantaneous change point of the mirror image (location 1310 in FIG. 3C ) to hide an object within the area, lens sheet 2500 cannot. However, lens sheet 2500 can utilize the shifting background to hide a target or to position the target in the fusion area of ​​the image. Setting the fusion area can be accomplished by moving the offset to the left or right of the second article of material in both lens sheet 2400 and lens sheet 2500 and does not need to be set in the central area of ​​the material.

[0195] Adding water between two pieces of single-sided lens sheeting 2300 to create lens sheeting 2400 provides transparency through the material that would be difficult to achieve without it. The water also helps mimic two pieces being manufactured as one piece, or two pieces being joined together, and provides the ability to move each of the two single-sided lens sheets separately with some opposing pressure on each piece for experimentation.

[0196] Concealed movement of the target object Among the advantages of some embodiments of the present invention is the ability of the lens sheeting material to conceal from the viewer the movement of moving or mobile objects behind the lens sheeting, in addition to camouflaging or hiding the objects themselves.

[0197] This is advantageous over the use of static camouflage, which is often limited in its ability to conceal a target object when the object is mobile. Even the best static camouflage is limited when an object is moving, as movement presents an anomaly or anomaly to the viewer, providing an element of detection and aiding in target recognition. Local visibility can better determine detail relative to peripheral visibility. When properly constructed, the lens sheet conceals most or all visual cues associated with the target's movement.

[0198] The inventors have found that a riot shield with a vertically extending lenticular lens article can conceal most of the covered target.

[0199] Riot Shield Implementation Example An exemplary embodiment of the present invention is a riot shield. Figure 46 depicts a riot shield 4600 having a clear shield body 4604 and a lens sheet 4606 disposed on the shield body 4604.

[0200] In such embodiments where the distance between the person holding the shield using the handles 4610, 4612 and the clear shield body 4604 is short, the lens sheet 4606 in the clear riot shield body depicts more of the background and provides camouflage to hide the object 4608 in the form of the person holding the shield 4600.

[0201] The reason lens sheet 4606 in riot shield 4600 shows the background well is that the lens polarization is vertical, which preserves horizontal elements such as horizontal edges while hiding people with a vertical aspect ratio that has height greater than width. Lens sheet 4606 refracts the horizontal and hides the vertical.

[0202] Lens lenses with longer handles and / or larger angles will improve the effect. The larger the angle in the lens, the closer you can get to the target without it being seen.

[0203] Lens sheet 4606 in riot shield 4600 is similar to lens sheet 2300 of FIG. 23b, which may be referred to in this disclosure as version 1. However, other versions, such as lens sheet 2500 of FIG. 25b (which may be referred to as version 3), may be used instead and may be more effective, enhancing background detail seen through the lens sheet material and helping to reduce, minimize, or even eliminate lens flare that occurs with lens sheet 2300 when a very bright light source is behind lens sheet 2300.

[0204] Vehicle windows In addition to riot shields, lens sheeting such as lens sheeting 4606 finds application in the windows of vehicles carrying one or more VIPs or important guests in the back. From the outside, no one in the back seat is visible, and the window over which the lens sheeting is overlaid appears clear, or simply a slightly tinted window. In situations where window tinting is not permitted due to prohibitions, laws, regulations, or modifications, VIPs traveling in the vehicle may be highly visible and vulnerable to attack.

[0205] Avoiding Airborne Object Detection - Umbrella An exemplary simple yet effective method of concealing a target on the ground from aerial detection by an overhead camera, aircraft, or drone while maintaining mobility involves the use of an umbrella with the exemplary lens sheeting material in one of the versions or embodiments described above.

[0206] Figures 47, 48, and 49 respectively depict example embodiments of such umbrellas in the form of umbrella 4700, umbrella 4800, and umbrella 4900. As seen in Figures 50 and 51, such umbrellas provide background or ground color while concealing the movement of target object 5002, which would not be detected unless viewed from a different angle to see the target object underneath the umbrella.

[0207] Such an umbrella or umbrella-like embodiment conceals the identity of a target object, which may include a person or their important equipment that is high enough to be concealed, such as on their back.

[0208] Of course, larger umbrellas conceal larger areas, and modified umbrellas that use lens sheeting that comes closer to the ground, such as umbrella 4800 in FIG. 48, can conceal an entire person even from a side view or oblique viewing position.

[0209] In the embodiment depicted in Figure 50, lens sheet 5004 may be a single-sided lens sheet similar to lens sheet 2300. As will be apparent to one skilled in the art, other embodiments of the exemplary lens sheet described above may also be used to avoid aerial detection of moving persons or equipment. Lens sheet 5004 may be scaled to provide aerial cover or camouflage for much larger objects. Figure 51 depicts another view of the camouflage of target object 5002 by lens sheet 5004.

[0210] Figure 52 depicts a target object 5002 in the form of a tank, which casts a shadow including a shadow 5008 of the tank's gun barrel 5010. Figure 53 depicts the same target object 5002 in the form of a miniature tank model beneath a lens sheet 5006. Lens sheet 5006 in this embodiment is made from the same lens material as lens sheet 5004, etc., and is used to protect the tank from detection from the air while it is moving.

[0211] The lens sheet 5006 is positioned above the tank and may be secured in a position elevated enough to allow sufficient standoff distance to obscure the tank from overhead threats. Suitable longitudinal supports are used to elevate the lens sheet 5006.

[0212] Any movement of object 5002 results in minimal anomalies or artifacts, and thus the moving object is well hidden from detection from overhead. An anti-reflective coating on lens sheet 5006 further reduces light reflections. For the tank, the shadow 5008 of the barrel of gun 5010 visible in Figure 52 is also no longer clearly visible in Figure 53. The image in Figure 53 was taken with approximately 16 halogen light sources in a room, so a single light source, such as the sun, would result in an even fainter shadow, if detectable at all.

[0213] FIG. 54 depicts a photograph of the embodiment shown in FIG. 53 using military grade night vision equipment, showing that the effect works across a wide range of the electromagnetic spectrum.

[0214] FIG. 55 depicts an object 5500 in the form of a quadcopter drone to which a lens sheet has been applied prior to takeoff so that the drone can be tested to see if it still functions and flies as expected.

[0215] In Fig. 56a, lens sheeting 5502 has been applied to the front and rear security of a quadcopter drone object 5500. The sides are uncovered to show the difference in concealment that results from sheeting 5502. Reflections can be reduced with anti-reflective coatings, or by using a wavy or semi-random set of waves in the mold for the lens, or by using a mesh cover over the lens.

[0216] Figure 56b depicts a drone object 5500 with the blade protection removed and a lens sheet 5502 wrapped around the drone object 5500 in a cylindrical shape. This embodiment removes the protective material that was visible to the lenses, providing better concealment. When the blades rotate quickly, there are no highly visible parts of the blades to hide. Most drones fly at head height above the observer, so there is little need to conceal the top of the drone.

[0217] The embodiments depicted in Figures 55 and 56a-b may be used with helicopters that use rotors to lift the vehicle and tilt the rotors to adjust the pitch of the blades to move the vehicle forward, backward, or side-to-side. Fixed-wing aircraft, or tilt-rotor technology to combine the vertical performance of a helicopter with the speed and range of a fixed-wing aircraft, may be much more challenging to apply.

[0218] Again, reflections can be reduced with anti-reflective coatings, or by using a wavy or semi-random set of waves in the mold for the lens, or with other lens sheeting embodiments disclosed above that reduce lens flare. The lens sheeting embodiment discussed above with reference to Figures 24a-b (Version 2) may work best because the effect of a mirror image against the sky as a background may be less noticeable than it could be on the ground. Reducing reflections from light results in a significantly smaller visual signature, and at typical viewing distances, the drone object may not be visible to viewers on the ground.

[0219] 57a-57d are diagrams of an object in the form of a model tank utilizing cylindrical lens sheeting 5700 to avoid detection of at least a portion of the object. One can conceal the tank's commander by positioning him inside cylindrical lens sheeting 5700, as shown in FIG. 57b. When cylindrical lens sheeting 5700 is positioned on the ground beside the tank, the commander is behind cylindrical lens sheeting 5700, as shown in FIG. 57d, and can see ahead without material in the commander's field of view, but the commander is difficult to detect from the side.

[0220] Mobile communication tower A sufficiently large lens sheet can conceal almost any target object, however safety considerations must be taken into account in certain environments, such as when concealing a mobile communications tower from view from the ground.

[0221] Wrapping a cylinder around a mobile communication tower at an appropriate standoff distance would also hide the tower from aircraft, which is unacceptable in most cases. The proposed method of an example embodiment of the present invention hides a mobile communication tower, large antenna, or any elongated member or structure from observation from the ground while still allowing observation from overhead as demonstrated in Figures 58a, 58b, 58c, and 58d.

[0222] A mobile communication tower 5800 having multiple lens sheets 5802 arranged at an angle as shown in Figure 58b makes the mobile communication tower 5800 nearly invisible from an overhead view 5804 as shown in Figure 58c. However, the arrangement shown in Figure 58b can allow a portion of the tower 5800 to be included in an overhead view 5806 (e.g., a view from an aircraft or drone flying overhead) as shown in Figure 58d.

[0223] Privacy inserts for hunting blinds and fences Hunting blinds can be made from lenticular sheeting material to allow hunters to use one blind for several environments, seasons, and times of day. Another exemplary use according to embodiments of the present invention is a chain link fence privacy insert made using lenticular sheeting, as shown in Figures 59a-59b.

[0224] An example lens sheet version 1, such as lens sheet 2300 of Figure 23b, provides a good ambiguity color match for homeowners. Versions 2-9 provide a detailed view of the background, but some objects can be hidden as previously mentioned.

[0225] Lens sheeting arrangements Version 10 (depicted in Figures 35-36), Version 11 (depicted in Figures 37-38), and Version 12 (depicted in Figures 39-41) can be used to provide color-matched camouflage so that nothing can be identified through the lens sheeting material.

[0226] Version 13 (depicted in Figures 42-45) can be utilized with either a permanent double-sided lens sheeting manufactured with a set interference pattern, or two single-sided articles with a clear lubricant or oil between them and a mechanism for allowing the user to change the interference pattern by adjusting the offset.

[0227] A soft, flexible lenticular sheeting material can be hung like a tent from poles or ropes, or can be supported by a rigid frame such as a pop-up tent. Cut-out holes in the material, as is done in modern camouflage netting, can be advantageous for camouflage, as shown in Figure 60.

[0228] 61a and 61b depict lying strips 6102 of lens sheeting in a net framework 6104. FIG.

[0229] FIG. 62 depicts an example embodiment that provides a camouflage sheet 6200 with a matrix of holes 6202 to provide viewing apertures while maintaining most of the camouflage's concealment while maintaining the structural integrity of the sheet. This allows for lighter weight and ventilation of the sheet 6200 when a target object is fully enveloped on all sides. The thermal signature through these holes is nearly imperceptible to a viewer because most of the target's heat is blocked by the solid portion of the sheet 6200. The viewer can detect something generating heat, but cannot identify the object. In other embodiments, the camouflage sheet shown in the example can be replaced with many different types of lens configurations with similar holes.

[0230] Lens sheet with variable lens elements In some embodiments, a lens sheet with variable lens elements can be used to control whether and where a neutral zone appears. As shown in FIG. 63, variable lenses, where not all lenses are exactly the same, can be used to create a lens sheet 6300. For example, the first set of lenses (from right to left) of lens sheet 6300 can be 100 LPI with a 42 degree field of view, the next middle set of 15 or so lenses can be 75 LPI with a 49 degree field of view, and the next set of lenses can be 50 LPI with a 54 degree field of view.

[0231] By placing other inconstant lenses behind it, the lens sheet 6300 can be made on both sides, and different configurations can be used to make the neutral zone larger or smaller, or even to eliminate the neutral zone entirely.

[0232] In other embodiments, the lens sheets depicted in Figures 35-45 can be manufactured not only as single-sided lenses, but potentially as double-sided lens sheets, or two double-sided lens sheets with or without offset. The lenses on the second side are made to match the angles and lenses on the opposite side. In other embodiments, the lens sheets depicted in Figures 35-45 can be manufactured not only as single-sided lenses, but as lens sheet assemblies made from one or more double-sided lens sheets with or without offset. The lenses on the second side need not match some, all, or either of the lenses on the opposite side. Such a configuration can allow the second side to be random or semi-random relative to the first side.

[0233] Other two-sided embodiments The embodiments shown in Figures 10-11 having one angle prism lenses and the embodiments of Figures 12-13 having two angle prism lenses can be used in double sided lens assemblies such as those shown in Figures 3C, 15 and 2, and double sided lens sheet assemblies such as Figures 16, 17a, 17b, 18-19, with varying lens sizes as depicted in Figures 26b, 27b, 28b, 29b, 30b and 31b, and with the configurations of Figures 35-45.

[0234] The Dove prism lens sheet of FIG. 14 may be split in the middle to allow for offset assembly and to allow for all of the configurations discussed in the paragraph above.

[0235] In other embodiments, the two side sheets can be the same LPI with different angles. A lens sheet assembly with two two side sheets can be made from a first two side lens sheet with the same first density LPI on both sides (e.g., 100 LPI) and a second two side sheet with the same but different density on both sides (e.g., 75 LPI).

[0236] Adding a flame orange tint to a lens sheet or part of a lens sheet assembly for hunting and other wildlife applications is advantageous because it allows humans to see through the sheet but not animals with dichromatic vision. Adding a high visibility tint may also be used commercially for safety purposes.

[0237] In other embodiments involving double-sided lenses, the lenticule sides may face each other rather than away from each other. An anti-reflective layer, coating, mesh cover, textured surface, or other overlay may be required on the smooth surface facing away from the target, and may also be required on the smooth surface facing toward the target.

[0238] In other embodiments involving double-sided lenses, the prism sides for the prismatic lenses may face each other rather than away from each other. An anti-reflective layer, coating, mesh cover, textured surface, or other may be required on the smooth surface facing away from the target, and may also be required on the smooth surface facing toward the target.

[0239] Anti-reflective coating The addition of an anti-reflective coating to the lenticular lenses enhances the use of the exemplary lens sheeting of embodiments of the present invention, as reflections can reduce the effectiveness of the lens sheeting and prevent widespread use of the exemplary methods of the present invention.

[0240] In some embodiments where the smooth surface of the single-sided Version 1 embodiment depicted in Figures 23a-23b faces the viewer, an anti-reflective treatment such as a coating, wavy lines, or mesh may be required on the side of the lenticule. In other applications where a double-sided lens sheeting has the side of the lenticule facing the viewer, a similar anti-reflective treatment may be required.

[0241] In addition to using anti-reflective coatings or wavy lines to disperse lens flare effects, it is possible to add mesh, such as an insect screen, to reduce the reflective glare that the sun or other light sources cause in the lens sheeting.

[0242] In the image depicted in Figure 64, the lens sheet has lenses that face and reflect fluorescent lights from the ceiling. The uncovered portion has a brightness of 249 on an RGB scale of 255 (a 24-bit color coding format with 8 bits per color), which is maximum pure white. The covered portion has a brightness of 135, which represents a 45.78% reduction.

[0243] In the image depicted in FIG. 65, taken from an experiment that did not attempt to use lens sheeting in this configuration to mimic a background, the reduction is 31.82%.

[0244] The insect screen is made from black mesh, so it is possible to use gray or clear plastic mesh for a better overall effect of reducing glare while still preserving the color of the background. Many types of mesh materials can be used to reduce glare.

[0245] In some embodiments, a mesh item, which may be black, white, colored, or clear mesh, may be added directly over the lens sheeting to create an anti-reflective coating.

[0246] In other embodiments, a mesh, which may be black, white, colored, or clear mesh, may be added directly onto the smooth side of the lens sheeting to create an anti-reflective coating. In some other embodiments, a textured surface may be added to the smooth side of the lens sheeting during manufacturing to create an anti-reflective surface. In still other embodiments, a textured surface may be added to some or all of the lenticules of the lens sheeting during manufacturing to create an anti-reflective surface.

[0247] Concealed assets in arch covers, structures, and buildings Arches are curved structures often used in residential, commercial, and military infrastructure because they provide column-free, open-plan interiors, very long lengths, and high ceilings. The strength of the arch also allows for additional protection from falling debris, rain, and snow. An added benefit of constructing a lens sheet in this manner is the often column-free open plan, and the arch can be positioned over a headgear, worn over the shoulder using a shoulder strap, or small enough to be attached to a backpack to conceal a person while allowing sufficient mobility.

[0248] When positioned on tanks, ships, aircraft, or buildings, arched lens sheeting can be used to conceal underlying objects and their shadows from visual, ultraviolet, infrared, or heat detection. An added benefit of the arch height is that any heat source from the underlying object will often be far enough from the lens sheeting to avoid heating the lens sheeting material and providing a detectable heat signature. The ends of the lens sheeting arch can be left open, or alternatively, can be fully or partially covered with the same lens sheeting material. Partial covering allows for airflow.

[0249] An exemplary arcuate lens sheet 6600 is shown in Figure 66. For purposes of illustration, a remote-controlled model tank 6602 is shown partially covered by the lens sheet 6600 in Figure 66.

[0250] Because lens sheet 6600 is expandable, creating a large-scale structure to conceal a real tank can be achieved simply by expanding the size of the lenses and lenticules that make up lens sheet 6600. The depicted lens sheet 6600, shown similar to version 1 of the embodiment with lenses discussed above and shown in Figures 23a-23b, is positioned horizontally to conceal a tank that is much longer in width than it is in height. Other exemplary versions of the lens sheet discussed above may also be used in this embodiment.

[0251] Because example lens sheet version 1 attempts to present the opposite polarization to the lenses, the only detectable elements after staring are some of the vertical lines on model tank 6602, and some vertical gaps between the wheels are detectable, but without a reference the observer may not be able to determine the threat.

[0252] Fig. 67 depicts an exemplary arcuate lens sheet 6700 used to conceal an object in the form of a rifle 6702. Figs. 68 and 69 depict lens sheet 6700 covering progressively larger portions of rifle 6702, thereby providing concealment from detection.

[0253] Snipers often hide in position for hours, waiting for a target to come into view. The sniper may not have the time or ability to move around freely to construct sniper cover, which is often made from objects found in the same location to camouflage the sniper's location. Therefore, the exemplary arcuate lens sheet 6700 shown in FIG. 67 can be used by the sniper to conceal the sniper's body and rifle 6702.

[0254] Another added benefit to a sniper, intelligence, reconnaissance, or spotter person or group is that open terrain with little cover that would otherwise allow them to be easily detected by the enemy now provides a place for hiding and observation.

[0255] To resist observation or infiltration by a sniper, an enemy will often select a location surrounded by open terrain with no cover, such as trees, bushes, stumps, large rocks, or hills. The sniper can use the lens sheet 6700 as a front shield to quickly move to an open terrain position undetected, which would take much longer without the concealing properties of the lens sheet 6700 to avoid detection. Arch structures can conceal the sniper from observation from above and can also be erected to conceal from observation from the side. Currently, snipers must remain as still as possible to avoid detection, but if locations in front and behind the sniper are concealed with the lens sheet 6700, movement detection is reduced or eliminated, allowing greater freedom of movement.

[0256] While arches such as the arch lens sheet 6700 can be self-supporting, other arches may be supported by solid arches at each end which can be made from solid molded arches, or flexible rods that regain their original shape when unfolded like a pop-up tent. Support arches may be required at predetermined lengths throughout the structure.

[0257] Additional strength for larger items Large arcuate lens sheets may require additional support. An exemplary support structure that may be utilized is a clear corrugated material, such as corrugated material 7000 shown in Figure 70. Lenticular lenses may be molded into the corrugations to combine the structural integrity of the corrugations with the concealing effect of the lens material.

[0258] Another exemplary structure that can be used is lenticular material 7100 having corrugations that include an article that acts as a lens on a support structure as shown in Figure 71. The nature of the shape of corrugated material 7000 is somewhat similar in shape to lenticular lenses. Lenticular lenses may be formed into these corrugations or other shapes not shown.

[0259] Lens sheets of very large dimensions can be manufactured similar to FIG. 2, with the width of each lenticule measured in inches, feet, yards, or larger diameters to allow for expansion for use in an aircraft hangar 7200 or other large structure such as that shown in FIG. 72.

[0260] Hollow lenticule and temperature control Because the weight of lenses of large dimensions may be unwieldy for transportation purposes, the lenses may be made hollow to be shipped and assembled in place, and then filled with a clear fluid such as water to enable the camouflaging function of the lenticules. Versions of any of the previously discussed embodiments may be scaled up in this manner, and other waveforms may be produced.

[0261] The shape of the lens sheet structure is not limited to the arch embodiment, and many variations can be used to create an open, column-free structure for better camouflage than could be achieved in structures that required structural columns. The examples shown in Figures 70, 71, and 72 are merely illustrative and in no way limiting.

[0262] Lens lenses for large-scale applications can be later filled with a fluid such as water, or if a more permanent structure is desired, can be filled with a clear liquid that solidifies into a transparent medium. This allows the final lens sheet to function as expected. The lightweight, hollow lenticular material can be removed like a mold once the clear liquid has solidified to take the shape of the lenticule.

[0263] Some or all of the liquid may be temperature conditioned so that the heating liquid does not create a temperature signature. Alternatively, temperature conditioning may be used to create a thermal signature for decoys such as livestock instead of tanks, or to create a heat signature that mimics a car instead of a tank. Such thermal conditioning can be important in naval applications where water is typically cooler than the surrounding air, allowing for easier thermal detection of ships, swimmers, and divers at the surface. Concealment in naval applications in this range of the infrared and thermal spectrum may require materials that are cooled to match the water temperature to avoid detection.

[0264] Temperature regulation may be used on drones or aircraft in the air, as lens sheets made from hollow or flat lenticules typically take on the ambient air temperature near the ground, which is usually warmer than the sky, so that a drone with an exemplary lens sheet at an altitude of, for example, 100 meters will be detectable against a cool sky background.

[0265] Temperature regulation can be achieved by circulating a fluid such as water through a hollow lens structure for naval or terrestrial applications, but other systems may be employed for solid lenticular sheets, such as blowing hot or cold air onto the material from the side of the target object, or in some cases, from the opposite side.

[0266] Regulating the temperature of at least one of the plurality of elongated lenses may also be achieved by one or more of blowing warm air, blowing cold air, electrical heating, or electrical cooling.

[0267] When using any of the above embodiments of a lens sheet or lens sheet assembly, it may be necessary to provide a viewing area for viewing through the lens sheeting. One way to do so is to utilize a small camera or pinhole camera attached to the lens sheeting that is secured to the surface of the material, or provided on one or more edges of the lens sheeting. A screen for use with the camera can be hidden a sufficient distance behind the lens sheeting so that a visible signature is reduced or eliminated. Eyeglasses or goggles with a screen or projected view onto them, or a separate viewing screen can be used. In the case of a 360-degree camera, a human target can utilize this technology for greater situational awareness while remaining hidden.

[0268] Conducting reconnaissance may require these cameras to transmit to other locations and / or to conceal the presence of the reconnaissance system in any location. The target object to be concealed need not be a person, but could be equipment, sensors, solar panels, cameras, technology, or other installations or devices that potentially require external viewing and analysis.

[0269] A simple and visible solution is provided in Figure 62 to create a matrix of holes to allow subsequent hidden targets to be seen through those areas while keeping the targets hidden. In applications where heat detection protection is required, the matrix of holes may be clear areas of the same material as the lens to allow line of sight to the outside while preventing heat gain of any subsequent targets.

[0270] A simple sight glass that is open or solid and clear, or a movable sight glass flap, may be sufficient for certain applications where the eye or head signature is the only detectable part of the target, and may be acceptable in many applications.

[0271] Another solution to the visibility area is to perforate the lens sheeting with holes, as is done in vinyl advertisements for bus windows, so that viewers close to the sheeting can see out, but people at greater distances outside attempting to capture a target cannot see through the perforations. These perforations can be large or small and can be holes that can be formed during or after manufacturing. Such holes can be filled with a clear material during the manufacturing stage. Visible perforations can take many different shapes, including, but not limited to, linear, circular, oval, square, rectangular, triangular, pentagonal, polygonal, etc.

[0272] protective sheet To protect the lens surface from scratches, dirt, dust, etc., it may be necessary to manufacture a clear protective sheet or surface that can cover the elongated lenses or lenticules to make the lens sheet more durable and resistant to water accumulation, dirt, scratches, and other things that may reduce the overall effectiveness. The protective layer may be formed by a coating or manufactured with a protective element to resist fog, water, fire, dirt, dust, scratches, heat, cold, UV rays, etc.

[0273] The protective sheeting covering the elongated lenses may utilize anti-reflective layers, coatings, mesh covers, textured surfaces, or other overlays.

[0274] Having described embodiments of the present invention by way of example only, it will be understood that the invention as defined by the appended claims is not limited to the specific details set forth in the foregoing description of exemplary embodiments, as many variations and substitutions are possible without departing from the scope of the claims. [Explanation of symbols]

[0275] 102 First Medium 104 Second Medium 106 Incident ray 108 Refracted Light Rays 110 Boundary 200 lenticular sheets 202 Lens, Lenticular 204 viewing angle 302, 302' light source 304, 304' lenticular lens 306, 306' lens sheet 308, 308' incident ray 308b, 308b' Unrefracted rays 310, 310' target 312, 312' refracted rays 402 Light source 404, 404' lenticular lens 406 First sheet, lens sheet 406' 2nd seat 408 Ray of light 410 Target 412 refracted light rays 530 Lens Sheet 532 videos 534 Lenticular Lens 536 Smooth rear 538 viewing angle 602 Target 603 Blind spot 604 Lenticular Lens 606 Lens Sheet 609 Refracted Light Rays 610 Viewer 702 Observer 710 Target 712 Incident ray 714 Cylindrical Wall 802 Lens Sheet 804 Linear lenses, lenticular lenses 806 refracted light rays 808 Viewer 810 Target 902 Lens Sheet 904 Linear Lens 906 Refracted Light Rays 908 Viewer 910 Target 912 Video 1000 Prism Sheet 1002 One Angle Prism Lens 1004 One Angle 1102 Ray of light 1106 Target 1108 Observer 1200 Prism Sheet 1202 Two-angle prism lens 1206 Ray of light 1208 Observer 1210 Target 1300 Double-sided linear lens sheet 1304 Ray of light 1306 Lens 1308 Reflected Light 1310 Location 1310' Focusing point 1400 Dove Prism Lens Sheet, Lens Sheet 1402 Location 1404 Ray of light 1406 Prism 1408 Reflected Light 1410 Location 1500 double-sided lens sheet 1506, 1507 Lenses 1510 Convergence Point 1512 Lens 1514 Lens 1600 sheets 1600A First sheet, double-sided lens sheet with offset 1600B Second sheet, double-sided lens sheet in a row 1606, 1607, 1612, 1614 lenses 1610 Location 1700, 1700' sheet 1700A 1st sheet 1700B 2nd seat 1700C 1st seat 1700D 2nd seat 1702, 1702' object 1706, 1706', 1707, 1707' lenses 1710, 1710' location 1714, 1714', 1715, 1715' lenses 1800 seats 1800A First sheet, double-sided lens sheet 1800B Second sheet, double-sided lens sheet 1802 Object 1806, 1807, 1812, 1814 lenses 1810 Location 1900 sheets 1900A 1st sheet 1900B 2nd seat 1902 Object 1906, 1907, 1914, 1915 Lenses 1910 Location 2002 Lens Sheet 2004 Neutral Zone 2006 flagpole 2008 Repeat Area 2010 Background Scenery 2102 Lens sheet 2104 Neutral Zone 2106 Background Scenery 2108 Video 2202 Lens sheet 2204 Neutral Zone 2206 Background Scenery 2300, 2400, 2500 lens sheet 3200 One-sided lens sheet 3500 Single-sided lens sheet 3502 Angled Area 3700 One-sided lens sheet 3702 Angled Complex Area 3900 Single-sided lens sheet 4502, 4504 Lens Sheet 4506 Target 4508 Viewer 4600 Riot Shield 4604 Shield body 4606 Lens Sheet 4608 Object 4610, 4612 Handles 4700, 4800, 4900 umbrellas 5002 Target, tank 5004 Lens sheet 5006 Lens sheet 5008 Shade 5010 Gun barrel, gun 5500 Object 5502 Lens sheet 5700 Cylindrical lens sheet 5800 Mobile Communication Tower 5802 Lens sheet 5804 Scenery 6102 Strip 6104 Net frame 6200 Camouflage Sheet 6202 hole 6300 Lens Sheet 6600 Arcuate Lens Sheet 6602 Model Tank 6700 Arcuate Lens Sheet 6702 Rifle 7000 corrugated material 7100 Lenticule material 7200 Aircraft Hangar d distance D separation distance P1 initial point P2 points R radius θ1 Angle of incidence θ2 refraction angle Δx offset distance

Claims

[Claim 1] A lens sheet having a first side and a second side opposite the first side, wherein at least one of the first side and the second side comprises: a first plurality of elongated lenses arranged substantially parallel in a first direction at a first density; a second plurality of elongated lenses arranged substantially parallel at a second density in a second direction different from the first direction; Equipped with A lens sheet, wherein the first plurality of elongated lenses and the second plurality of elongated lenses are made from a substantially light-transmitting material.

Images