Nano fractal diffuser

• US 8,248,696 B2
• Filed: 06/25/2009
• Issued: 08/21/2012
• Est. Priority Date: 06/25/2009
• Status: Expired due to Fees

• Current Assignee: Moxtek (Polatechno Co.,Ltd.)
• Original Assignee: Moxtek (Polatechno Co.,Ltd.)
• Inventors: Lines, Michael, Davis, Mark, Gardner, Eric W.
• Primary Examiner(s): Shafer, Ricky D
• Application Number:
  US12/491,513
• Publication Number:
  US 20100328768A1
• Time in Patent Office: 1,153 Days
• Field of Search: 359/485.05, 359/569, 359/572, 359/573, 359/574, 359/575, 359/576, 359/599
• US Class Current: 359/485.05
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: G02B 5/0252 using holographic or diffractive means
• CPC Class Codes: G02B 5/1814 structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings G02B5/189 takes precedence
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles

Abstract

A diffusive device has an array of discrete facets which may be of a size and pattern similar to a fractal. The facet dimensions can be greater than half the wavelength of incident light such that the facets substantially diffract light. A polarizing wire-grid layer comprised of an array of elongated parallel conductive wires with a period less than half the wavelength of incident light may be disposed between, beneath, or above the facets. The wire-grid polarizes the light by substantially reflecting light having an s-polarization orientation and substantially transmitting a portion of light having a p-polarization orientation.

Claims

1. A diffusive wire grid polarizer device, comprising:

a) a substrate having a top surface and a bottom surface;

b) at least one layer disposed over the top surface of the substrate;

c) a wire grid formed in one of the at least one layer including an array of elongated parallel conductive wires with P_WGP<

λ

/2, where P_WGP is the period of the wires, and λ

is the wavelength of light incident on the wires, to polarize the light by substantially reflecting light having an s-polarization orientation and substantially transmitting light having a p-polarization orientation incident on the array;

d) at least sixteen facets of at least two different sizes formed in one of the at least one layer with a facet dimension transverse to the wires greater than λ

/2 to substantially diffract both s-polarized light and p-polarized light incident on the at least two facets; and

e) the at least sixteen facets forming distinct groups arranged in a fractal pattern.

2. A device as in claim 1, wherein the wire grid and the at least sixteen facets comprise a single layer such that the at least sixteen facets are interspersed through the array of wires and interrupt the array of wires.

3. A device as in claim 1, wherein the at least sixteen facets form distinct groups in the array of wires with four different sizes arranged in the fractal pattern.

4. A device as in claim 1, wherein the at least sixteen facets further includes four different sizes and four different surface areas.

5. A device as in claim 1, wherein the at least one layer includes at least two layers with one of the at least two layers containing the wire grid and a different one of the at least two layers containing the at least sixteen facets.

6. A device as in claim 5, wherein a distance from the bottom surface of the substrate to a top surface of at least one of the at least sixteen facets is different than a distance from the bottom surface of the substrate to a top surface of another of the at least sixteen facets.

7. A device as in claim 1, wherein the at least one layer includes at least three layers, and wherein:

a) one of the at least three layers contains a wire grid;

b) a second of the at least three layers contains at least sixteen facets; and

c) a third of the at least three layers contains at least sixteen facets.

8. A device as in claim 1, wherein the at least one layer comprises:

a) at least two layers of a wire grid; and

b) at least three layers containing at least sixteen facets in each layer.

9. A device as in claim 1, wherein the at least sixteen facets are a solid material surrounded by areas of the layer which have been removed.

10. A device as in claim 1, wherein the at least sixteen facets are comprised of areas of the layer which have been removed, and are surrounded by areas of the layer which have not been removed.

11. A device as in claim 1, wherein a distance from the bottom surface of the substrate to a top surface of at least one of the at least sixteen facets is different than a distance from the bottom surface of the substrate to a top surface of another of the at least sixteen facets.

12. A device as in claim 1, wherein areas of the top surface of the substrate which is not covered with any of the at least sixteen facets is covered by the wire grid and the top surface of the at least sixteen facets is covered with the wire grid.

13. A device as in claim 1, wherein tops of the wires and tops of the facets terminate in a common plane.