Optical security device based on a surface of revolution
An optical article printed on a substrate may include an organic binder; and a plurality of reflective magnetic platelets provided in the organic binder, wherein the plurality of reflective magnetic platelets are substantially aligned in accordance with at least part of a surface of revolution, and wherein the plurality of reflective magnetic platelets are aligned to cause a first reflective effect of the optical article when the substrate is rotated around a first axis and to cause a second reflective effect of the optical article when the substrate is rotated around a second axis, wherein the first reflective effect is different from the second reflective effect.
1. An optical article printed on a substrate, comprising:
an organic binder; and
a plurality of reflective magnetic platelets provided in the organic binder,
wherein the plurality of reflective magnetic platelets are aligned in accordance with at least part of a surface of revolution, and
wherein the plurality of reflective magnetic platelets are aligned to cause a first reflective effect of the optical article when the substrate is rotated around a first axis and to cause a second reflective effect of the optical article when the substrate is rotated around a second axis,
wherein the first reflective effect is different from the second reflective effect, and
wherein the first reflective effect is a first movement of left and right portions of a reflection from the optical article that is larger than a second movement of a center portion of the reflection from the optical article.
2. The optical article of claim 1 , wherein the surface of revolution is funnel-shaped.
3. The optical article of claim 1 , wherein the surface of revolution is defined based on a parabola or hyperbola.
4. The optical article of claim 1 , wherein the surface of revolution is shaped as a hyperbolic paraboloid.
5. The optical article of claim 1 , wherein the first axis is a horizontal axis and the second axis is a vertical axis.
6. The optical article of claim 1 , wherein the first axis is orthogonal to the second axis.
7. The optical article of claim 1 , wherein the surface of revolution is defined based on a natural logarithm.
8. A method for forming an optical article on a substrate, comprising:
providing an organic binder that includes a plurality of reflective magnetic platelets on the substrate;
applying a magnetic field to the organic binder using one or more magnets,
wherein the one or more magnets include two magnets provided parallel to each other,
wherein a corner of the two magnets is cut off or rounded,
wherein the magnetic field aligns the plurality of reflective magnetic platelets in accordance with at least part of a surface of revolution,
wherein the plurality of reflective magnetic platelets are aligned to cause a first reflective effect of the optical article when the substrate is rotated around a first axis and to cause a second reflective effect of the optical article when the substrate is rotated around a second axis, and
wherein the first reflective effect is different from the second reflective effect; and
setting or hardening the organic binder.
9. The method of claim 8 , wherein the surface of revolution is funnel-shaped.
10. The method of claim 8 , wherein the surface of revolution is shaped as a hyperbolic paraboloid.
11. The method of claim 8 , wherein the one or more magnets include two triangular magnets that are provided in a coplanar fashion.
12. The method of claim 11 , wherein first sides of the two triangular magnets are provided parallel to and distal from the organic binder, and wherein second sides of the two triangular magnets are provided perpendicular to the organic binder and in contact with each other.
13. The method of claim 8 , wherein the one or more magnets include a magnet with two or more triangular notches.
14. The method of claim 8 , wherein the first reflective effect and the second reflective effect are generated based on an angle of light or a viewing angle.
15. A document, comprising:
an optical article comprising a plurality of reflective magnetic platelets,
wherein the plurality of reflective magnetic platelets are aligned in accordance with at least part of a surface of revolution,
wherein the plurality of reflective magnetic platelets are aligned to cause a first reflective effect of the optical article when the optical article is rotated around a first axis and to cause a second reflective effect of the optical article when the optical article is rotated around a second axis,
wherein the first reflective effect is different from the second reflective effect, and
wherein the second reflective effect is a brightening of a first portion of a reflection from the optical article and a darkening of a second portion of the reflection from the optical article.
16. The document of claim 15 , wherein the first reflective effect is a widening of a first portion of a reflection from the optical article and a narrowing from a second portion of the reflection the optical article.
17. The document of claim 15 , wherein the second reflective effect is further a first lateral motion of a first portion of a reflection from the optical article that is larger than a second lateral motion of a second portion of the reflection from the optical article.
18. The document of claim 15 , wherein the first reflective effect is a first movement of left and right portions of a reflection from the optical article that is larger than a second movement of a center portion of the reflection from the optical article.
19. The document of claim 15 , wherein the first axis is a horizontal axis and the second axis is a vertical axis.
20. The document of claim 15 , wherein the first reflective effect and the second reflective effect are generated based on an angle of light or a viewing angle.