Systems and methods to impart visual quality to illumination systems
Implementations disclosed herein include optical sheets comprising one or more regions including one or more optical elements. Each of the one or more optical elements includes a plurality of microstructures. The one or more optical elements can be configured to tailor the radiation pattern output from a source of illumination. The one or more optical element can be further configured to impart a visual appearance to the optical sheet that is different from a standard lenticular or prismatic sheet. In various implementations, the one or more regions can be demarcated from each other or the surrounding by borders. The borders of the one or more regions can be configured to form one or more letters, one or more symbols or logos for identification and/or security purposes. Various implementations of the optical sheet can include nano-particles in addition to the optical elements to enhance the aesthetic quality of the optical film.
1. An optical sheet comprising:
a first region comprising one or more optical elements, at least one of the one or more optical elements including a plurality of microstructures, the one or more optical elements configured to alter a far-field radiation pattern of an incident beam, the first region including a central portion and a border configured to visually demarcate the first region from a surrounding area,
wherein a portion of the border is configured to form at least one of text, a letter, a symbol, a number, an image, a picture or a character, and
wherein a dimension of the text, the letter, the symbol, the number, the image, the picture or the character is between about 0.01 % and about 50 % of a corresponding dimension of the central portion such that the text, the letter, the symbol, the number, the image, the picture or the character is not resolved by a naked human eye without aid of magnification.
2. The optical sheet of claim 1 , wherein at least one of the one or more optical elements includes a Fresnel lens.
3. The optical sheet of claim 1 , wherein a section of the border forms a logo.
4. The optical sheet of claim 1 , wherein the plurality of microstructures includes at least one of a planar facet, a curved facet, a linear groove, a curvilinear groove or a holographic feature.
5. The optical sheet of claim 1 , wherein the surrounding area includes a second region comprising one or more optical elements, at least one of the one or more optical elements of the second region including a plurality of microstructures, the second region including a central portion and a border, wherein the second region is visually demarcated from the first region.
6. An illumination system comprising:
a source of illumination; and
the optical sheet of claim 1 disposed forward of the source of illumination.
7. The optical sheet of claim 1 , wherein the portion of the border is configured to form a text.
8. The optical sheet of claim 1 , wherein the portion of the border is configured to form a letter.
9. The optical sheet of claim 1 , wherein the portion of the border is configured to form a symbol.
10. The optical sheet of claim 1 , wherein the portion of the border is configured to form a number.
11. The optical sheet of claim 1 , wherein the portion of the border is configured to form a character.
12. The optical sheet of claim 1 , wherein the one or more optical elements are arranged randomly.
13. The optical sheet of claim 5 , wherein the second region surrounds the first region.
14. The optical sheet of claim 5 , wherein the second region adjoins the first region.
15. The illumination system of claim 6 , wherein the source of illumination comprises at least one of one or more LEDs, a small volume incandescent bulb or a fluorescent bulb.
16. The illumination system of claim 6 , wherein the far-field radiation pattern is selected from a spot light, a flood light or a wash light.
17. The optical sheet of claim 14 , wherein the border is the interface between the first region and the second region.
18. An optical sheet comprising:
a plurality of optical elements, at least one optical element of the plurality of optical elements including a curved groove disposed around an optical axis of the at least one optical element, the curved groove having a primary optical facet and a secondary optical facet disposed at an angle with respect to the primary optical facet,
wherein the primary optical facet is disposed at a facet angle α less than about 90 degrees with respect to the optical sheet,
wherein the secondary optical facet is disposed at a facet angle β less than about 90 degrees with respect to a normal to the optical sheet, and
wherein the facet angle α departs from a nominal value α nominal by an amount Δα, wherein a value of α nominal at a distance r 0 from the optical axis is determined from a monotonic curve that varies monotonically with distance r 0 from the optical axis, and wherein Δα is determined by an undulating curve superimposed on the monotonic curve.
19. The optical sheet of claim 18 , wherein α nominal varies parabolically or quadratically with distance r 0 .
20. An illumination system comprising:
a plurality of light emitting diodes; and
the optical sheet of claim 18 disposed forward of the plurality of light emitting diodes.
21. The optical sheet of claim 18 , wherein the plurality of optical elements are arranged randomly.
22. The optical sheet of claim 18 , wherein the at least one optical element comprises a plurality of curved grooves.