Dynamic appearance-changing optical devices (DACOD) printed in a shaped magnetic field including printable fresnel structures
A printed image is disclosed wherein the image may be in the form of an array of magnetically aligned platelets or flakes that may by uniform in shape and size and wherein the flakes are arranged in a particularly manner to form optically illusive images useful as security devices, or useful in beam steering applications. In one embodiment of this invention printed array is disclosed a plurality of concentric rings of magnetically aligned platelets disposed upon a substrate in the form of a Fresnel structure, preferably a Fresnel reflector. Advantageously, since the magnetic field can be controlled with respect to strength and direction, one can easily design a field that will correct for spherical aberration that would otherwise be present in a typical Fresnel reflector. In other embodiments of the invention optically illusive images of funnels, domes and cones are printed.
1. An optically illusive image comprising a substrate having a region of flakes coating a surface of the substrate, wherein the flakes are distributed throughout substantially the region and oriented in a predetermined pattern therein, and wherein the flakes are oriented such that lines normal to a reflecting surface of each of the flakes converge to a point.
2. The optically illusive image of claim 1 , wherein the flakes are oriented in a pattern that define a concave structure.
3. The optically illusive image of claim 1 , wherein a quantity of the flakes is greater than 1000.
4. A label or security device comprising an optically illusive image having flakes covering and distributed throughout an entire region of a substrate and oriented in a predetermined pattern, each of the flakes having a reflecting surface, wherein the predetermined pattern of the flakes is such that lines normal to the reflecting surface of each of the flakes converge to a point, and wherein the predetermined pattern has an axis of revolution.
5. The label or security device of claim 4 , wherein a quantity of the flakes is greater than 1000.
6. The label or security device of claim 4 , wherein an ink, with the flakes, is printed on the substrate.
7. An optical element comprising a plurality of concentric rings of magnetically aligned platelets disposed upon a substrate in a form of a Fresnel structure.
8. The optical element of claim 7 , wherein the Fresnel structure is a Fresnel reflector.
9. The optical element of claim 7 , wherein an ink, with the platelets, is printed on the substrate.
10. The optical element of claim 7 , wherein the Fresnel structure is a convex shaped structure.
11. An optical element, comprising a plurality of magnetically aligned flakes, disposed upon a substrate, oriented in a pattern defining a Fresnel concave or convex shaped structure, and wherein lines normal to a reflecting surface of each of the plurality of magnetically aligned flakes converge along a line.
12. The optical element of claim 11 , wherein the Fresnel concave or convex shaped structure is absent spherical aberration.
13. The optical element of claim 11 , wherein the line is normal to a surface of the optical element and goes through a center of the pattern.
14. The optical element of claim 11 , wherein a quantity of the plurality of magnetically aligned flakes is greater than 1000.