Nanostructure array diffractive optics for RGB and CMYK color displays
An RGB and/or CMYK full color optical display device comprising multiple nanostructure arrays configured to provide display of a wide range of colors corresponding to multiple pixels or sub-regions of an image is disclosed, where the multiple nanostructure arrays may be formed on a single substrate layer. An optical display device includes a substrate having a surface, and a first pixel of a color image comprising first and second sub-pixels according to at least one of an additive and subtractive color scheme, where the first sub-pixel comprises a first optical sub-wavelength nanostructure array formed on or in the surface of the substrate, and where the second sub-pixel comprises a second optical sub-wavelength nanostructure array formed on or in the surface of the substrate. A method of manufacturing an RGB and/or CMYK full color optical display comprising multiple nanostructure arrays arranged as sub-pixels according to a color scheme is also disclosed.
1. An optical display device formed on a surface of a substrate, the optical display device comprising:
a plurality of pixels of a color image, each pixel comprising first and second sub-pixels according to at least one of an additive and subtractive color scheme;
wherein said first sub-pixel comprises a first optical nanostructure array formed on or in the surface of said substrate;
wherein said second sub-pixel comprises a second optical nanostructure array formed on or in the surface of said substrate,
wherein said first and second optical nanostructure arrays each comprise a plurality of nanostructures and said nanostructures comprise one or more of nanoholes and nano-columns formed on or in said surface of said substrate,
wherein said first optical nanostructure array comprises nanostructures with a periodic spacing of 380 nm to 580 nm to produce a blue or green color by first order diffraction and the second optical nanostructure array comprises nanostructures with a periodic spacing of 580 nm to 680 nm to produce a red color by first order diffraction, whereby the first and second optical nanostructure arrays diffractively provide by the reflection of an incident light source the different colored sub-pixels of a pixel of the plurality of pixels.
2. The optical display device according to claim 1 , wherein the optical display device comprises an optical security device, and wherein said color image comprises optically visible features and is operable to visually authenticate an article comprising said optical security device.
3. The optical display device according to claim 1 , wherein said first nanostructure array is operable to diffract a reflected incident light source to define a first color of said first sub-pixel; and said second nanostructure array is operable to diffract a reflected incident light source to define a second color of said second sub-pixel.
4. The optical display device according to claim 1 , wherein said first nanostructure array comprises a plurality of nanostructures arranged in a first periodic lattice having a first periodic spacing between said nanostructures, and said second nanostructure array comprises a plurality of nanostructures arranged in a second periodic lattice having a second periodic spacing between said nanostructures, and wherein said first periodic spacing is different from said second periodic spacing.
5. The optical display device according to claim 4 , wherein said first and second periodic lattices each comprise one or more of a square, hexagonal, octagonal, pentagonal or Penrose lattice geometry.
6. The optical display device according to claim 1 , wherein said first and second sub-pixels of said first pixel of said color image are substantially overlaid on each other or interleaved with each other on said substrate.
7. The optical display device according to claim 1 , wherein said first and second sub-pixels of said first pixel of said color image are located substantially adjacent to each other on said substrate.
8. The optical display device according to claim 1 , wherein said substrate comprises a film, surface or layer of at least one of a metallic, polymer, composite, or cellulose substrate material, or combinations thereof.
9. The optical display device according to claim 1 , wherein said color scheme comprises an additive RGB color scheme.
10. The optical display device according to claim 9 , wherein said second sub-pixel comprises a red sub-pixel of said RGB color scheme.
11. The optical display device according to claim 9 , wherein said first optical nanostructure array comprises nanostructures with a periodic spacing of about 480 nm to 580 nm, and said first sub-pixel comprises a green sub-pixel of said RGB color scheme.
12. The optical display device according to claim 9 , wherein said first optical nanostructure array comprises nanostructures with a periodic spacing of about 380 nm to 480 nm, and said first sub-pixel comprises a blue sub-pixel of said RGB color scheme.
13. The optical display device according to claim 1 , wherein said color scheme comprises a subtractive CMYK color scheme.
14. The optical display device according to claim 1 , wherein said first and second nanostructure arrays each comprise a plurality of nanoholes formed in said substrate, said nanoholes comprising one or more of a circular, substantially round, elliptical, rectangular, triangular or square geometry.
15. A method of manufacturing an optical display device for providing a visual authentication method, comprising:
forming on a substrate, said substrate comprising a surface, a first pixel of a color image by:
forming a first optical nanostructure array on said substrate surface to form a first sub-pixel of said first pixel of a color image;
forming a second optical nanostructure array on said substrate surface to form a second sub-pixel of said first pixel of a color image;
wherein said first and second sub-pixels define a first color of said first pixel of said color image according to an additive or subtractive color scheme; and
forming on said substrate a second pixel of said color image by:
forming a third optical nanostructure array on said substrate surface to form a first sub-pixel of said second pixel of said color image;
forming a fourth optical nanostructure array on said substrate surface to form a second sub-pixel of said second pixel of said color image;
wherein said first and second sub-pixels define a second color of said second pixel of said color image according to an additive or subtractive color scheme;
wherein said first, second, third and fourth nanostructure arrays each comprise a plurality of nanostructures and said nanostructures comprise one or more of nanoholes and nano-columns formed on or in said surface of said substrate, and
wherein said first optical nanostructure array comprises nanostructures with a periodic spacing of 380 nm to 580 nm to produce a blue or green color by first order diffraction and the second optical nanostructure array comprises nanostructures with a periodic spacing of 580 nm to 680 nm to produce a red color by first order diffraction, whereby the first and second optical nanostructure arrays diffractively provide by the reflection of an incident light source the different colored sub-pixels of said first pixel.
16. The method of manufacturing an optical display device according to claim 15 , wherein forming said first and second nanostructure arrays comprises one or more of printing, imprinting, embossing, stamping, molding, etching or inscribing said nanostructure arrays in or on said substrate surface.
17. The method of manufacturing an optical display device according to claim 15 , wherein forming said first and second nanostructure arrays comprises writing said first and second nanostructure arrays by means of electron beam lithography.
18. The method of manufacturing an optical display device according to claim 15 , additionally comprising attaching said substrate to a security article as an optical security authentication device.