Invented by Hao Jiang, Reza Qarehbaghi, Bozena Kaminska, Mohamadreza Najiminaini, Jeffrey J. L. Carson, Mohamad Rezaei, Nanomedia Security Corp, NANOTECH SECURITY CORP
The Nanomedia Security Corp, NANOTECH SECURITY CORP invention works as followsDisplay media containing a pixel-layer containing subpixels that are composed of nanoscale structures, and an intensity control sheet which can pattern the luminance in the subpixels. Display media comprises a substrate, a subwavelength substrate supported on the substrate, subpixels with at least one subwavelength structure that has at least one optical property such as a specific band, and at least two subpixels each having a distinct optical property. An intensity control layer is used to control the luminance for each subpixel individually. Some subpixels can have colors to define a color spectrum, while others may have invisible radiation spectrum bands. The display media, for example, can allow both overt (color images), and covert (covert information) to be embedded with high density.
Background for Nanomedia information carrier based upon pixelated nanostructures combined together with an intensity control layers
Metallic nano-structures were demonstrated to have unique abilities to manipulate the light at nano-scale. Due to the coupling between the light and surface plasmons at the interface of a metal with a dielectric (SP), metallic sub-wavelength structure can display strong colors which are easily tunable by altering the geometry. Ebbesen et al. (U.S. Pat. No. 6,040,936, Mar. 21 2000) shows that a metal sheet with periodic arrays sub-wavelength holes can show extraordinary optical transmission, and be used as a color filter. The modulated filters allow light to be transmitted in any color. Kaminska et al. (U.S. Pat. No. No. Kumar et al. (Nat. Nanotechnol. Nanotechnol. Moreover, Wu et al. (Sci. Rep. 3,1194, 2013) shows that nano-cavities on a metal sheet can display primary colors without regard to angle.
Nano-gratings have been used to display optical information. Fattal et al. Nature 495, 348 (2012) explains that 1-D nanogratings can function as multi-directional backlights to display color images with multiple views. Nano-gratings are used for authentication and anti counterfeit applications. Lai et. al. have demonstrated this. (U.S. Pat. No. 7,113,690 B2, Sep. 26, 2006) and Schnieper et al. (U.S. Pat. No. 7,787,182 B2, Aug. 31, 2010; U.S. Pat. No. 8,270,050 B2, Sep. 18, 2012).
The production of color images with sub-wavelength structure can be useful for security documents and public relations. The color images produced by the existing systems are typically ‘bottom-up’. methodology, i.e. According to the color image, specific color pixels consisting of sub-wavelength structure are placed at the corresponding positions on the substrate. For each color image, the fabrication process uses expensive and lengthy techniques such as focused ion beam (FIB) and electron beam lithography. Chuo et al. (Nanotechnol. The Nanotechnol. Each new color image will require a new stamp, and the manufacturing process can be lengthy. Making a new stamp for every person in many cases is not feasible.
Color photography techniques using photographic film can produce color images quickly and at a low cost. Color pigments and film emulsions can cause inconsistencies or fade over time. “The color images created by conventional film-based colour photography can be easily copied and are not suitable for security purposes.
The detailed description of examples embodiments below may help you to understand other difficulties with existing methods, systems and techniques.
The invention relates to the production of visible color images or covert information by using sub-wavelength structure as color pixels or invisible pixels.
In an example embodiment, a display medium which can be called nano-media is provided, comprising a nanosubstrate consisting of arrays of nanostructures as the subpixels, and an intensity-control layer to pattern luminance in the subpixels.
In one example, the nano-substrate consists of a metal sheet with periodic arrays. The nano-structures allow for certain bands of visible light to be detected by the human eye and/or captured by reader devices.
In one embodiment, covert infrared and overt color images are embedded within a nano-media. A method and apparatus are provided for the production of the nanomedia.
In one example embodiment, a display medium is provided, comprising: a substrate; a subwavelength substrate supported on the substrate; and subpixels. Each subpixel is defined by atleast one subwavelength structure with atleast one specific optical characteristic, such as a specific band; at least two subpixels have a different specific property; and a control layer for controlling the luminance of individual subpixels within a pattern.
In another example embodiment, a display medium is provided, which includes a pixel with sub-wavelength structure having at least one optical property. At least two of these wavelength structures have a different optical property. A photo-sensitive film is also included, which can be optically altered to pattern the luminance for each sub-wavelength structure.
In an example embodiment, a method is provided for producing color images on a subwavelength substrate supported and including subpixels. Each subpixel is defined by atleast one subwavelength structure with at least one specific property including an optical band. At least two subpixels have a different specific property. The method includes: determining desired covert and/or overt information and patterning individual control subregions of an intensity-control layer according to the determined desired covert and/or overt information in order to control the amount
In an example embodiment of the invention, a display medium is provided, which includes: a substrate layer; sub-wavelength sub-structure supported by the substrate; pixels; each pixel defined by subpixels defined by sub-wavelength structures having at least a single specific optical property, such as a specific band; at least two subpixels of each pixel are different in terms of specific optical properties; and an intensification control layer for patterning the luminance amount of the subpixels.
In an example embodiment, a display medium is provided, which comprises a pixel with subwavelength structure having at least one optical property. At least two subwavelengths structures have a different optical property. A photo-sensitive film is also included, which can be optically altered to pattern the luminance for each subwavelength structure.
The method includes: determining the desired overt information, calculating the exposure image, and exposing said exposure image to the display media.
In some embodiments, sub-wavelength nanostructures are used as color pixels or invisible radiation pixels to produce visible color images. In one example embodiment, a display medium is provided, comprising a subwavelength substrate containing arrays of nanostructures as subpixels, and an intensity-control layer for patterning the luminance.
Referring now to FIG. In accordance with one example embodiment, FIG. 1A illustrates a display medium 100 that may be referred as a “nano-media” 100. Nano-media 100 is composed of substrate 10 (e.g. The substrate layer is composed of a sub-wavelength layer 12 (also known as nano-substrate 12), an intensity control layer 14 and a cover layer 15. Glass or polymer, for example, can be used as the material of substrate 10. Nano-substrate 12, which is constructed from nano-structures, is made up of arrays that can display visible colors or invisible bands of light, such as in the infrared range and/or ultraviolet. The intensity control layer 14 is made up of a material or layers of materials that are capable of individually modifying the luminance of subpixels in nano-substrate 12 The nano-substrate 12 is optically connected to the intensity control layer 14. It may be necessary to add additional layers between the substrate 10 and the nano-substrate 12. Also, between the nano-substrate and intensity control layer 14. This is done in order to ensure that all layers adhere well. Cover layer 15 is transparent, and acts as a protective layer or support layer over intensity control layer 14. On at least one layer of the nanomedia 100 there may be fiducial markings for accurately aligning nano-substrate with intensity control 14 as well as aligning nano-media to production equipment. In some embodiments, layers of the nano-media are arranged in a different sequence. The intensity control layer 14 may be placed beneath the nano-substrate in some cases, such as when the output is the transmission, scattering, or diffraction. In some examples, the layers of the nano-media can be altered according to the method used for embedding information.
In at least some embodiments, the term “sub-wavelength” can refer to a nanostructure, defined aperture, defined pillar or defined particle that is smaller than a wavelength of an electromagnetic field, light or radiation incident on the structure or aperture. In some embodiments, references to “nano” are also used. This invention can also be modified, configured, or applied to structures of other sizes, such as pico, micro, or smaller, depending on the application or incident electromagnetic field.
FIG. The mosaics of subpixels are shown in 1B on the nano-substrate 12 Each pixel 16 is composed of at least two subpixel types, typically located in the same area or close proximity. The pixel set 16 may, for example, include three primary colors subpixels. According to the RGB color scheme, red subpixel 18 is followed by green subpixel 20, and blue subpixel 22. The term’subpixels’ is used. The name’subpixels’ in example embodiments. In some embodiments, each set of pixels 16 can also include at least one type invisible subpixel 24 that transmits covert information using radiation in the infrared or ultraviolet bands. Each subpixel size can be between 200 nanometers and 500 micrometers, or even larger. Depending on the fabrication capability, the application, and the nature of electromagnetic fields incident, etc. Each subpixel is built with subwavelength structures. The sub-wavelength structures can be metal nano-hole arrays, metal nano-particles, metal nano-slits, metal nano-cavities, metal nano-hole-nano-particle hybrids or a metal film structured with periodic topography. Sub-wavelength metal structures can be made of any metal, such as aluminum (Al), chromium(Cr), copper or gold (Au). The pixel set 16, in the example embodiments, uses RGB color system to display visible colors. However, the pixel system 16 can also be constructed using CMY color systems with cyan subpixels, magenta subpixels, and yellow pixel. For example, the pixel set 16 can include more than four types of subpixels. In some embodiments, a pixel set can include subpixels that are defined by colors. The pixel set may include subpixels with at least two other optical properties, such as angle-dependence. (These may or may have the same optical bands).
The pixel set 16 has at least some subpixels that are close or far enough apart to allow the combined color of each subpixel to be seen or perceived. For example, in a 16-pixel pixel set, a 50% purple pixel and 50% red pixel are at a suitable distance so that their combined color can be perceived as violet/magenta by a human.
While the example embodiments show the subpixels as squares, they can also be circular or triangular. The locations of subpixels within each pixel 16 can be different from the example embodiments without departing from the teachings in the present disclosure. The subpixels and/or the pixel set 16 can be arranged as an array, grid, aperiodic and/or periodic arrangement.
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