Interference pigments or foils as separate structures having color match or mismatch depending on viewing angle
A method of providing a configuration of a system of interference filters with a visible color shifting effect, includes: a hue matching step of identifying a configuration of a first interference filter including two first metal layers and a first spacer layer therebetween, and a configuration of a second interference filter including two second metal layers and a second spacer layer therebetween, wherein the first and second filters match in hue at the first viewing angle, and the mismatch in hue at the second angle; and a lightness adjustment step which may include modifying the layer material or the layer thickness of one of the metal layers; wherein a difference in lightness at the first viewing angle between the first and second modified filters is less that a difference in lightness at the first viewing angle between the first and second filters.
1. A system comprising:
a first interference filter comprising:
a first reflector layer,
a first absorber layer comprising a light-absorber material and having a thickness H1, and
a first spacer layer between the first reflector layer and the first absorber layer; and
a second interference filter comprising:
a second reflector layer,
a second absorber layer comprising the light-absorber material and having a thickness H2 that is different from the thickness H1, and
a second spacer layer between the second reflector layer and the second absorber layer,
wherein the first interference filter and the second interference filter are separate structures,
wherein an optical thickness of the second spacer layer is different from an optical thickness of the first spacer layer,
wherein the first interference filter and the second interference filter match in hue, chroma, and lightness at a first viewing angle, and mismatch in hue at a second viewing angle, and
wherein a difference in color between the first interference filter and the second interference filter at the first viewing angle is less than a difference in color at the first viewing angle between two interference filters forming a first comparison pair, different from the first interference filter and the second interference filter only in that absorber layers in the two interference filters of the first comparison pair have the thickness H1, and is less than a difference in color at the first viewing angle between two interference filters forming a second comparison pair, different from the first interference filter and the second interference filter only in that absorber layers in the two interference filters of the second comparison pair have the thickness H2.
2. The system of claim 1 , further comprising:
a first foil comprising the first interference filter, and
a second foil comprising the second interference filter.
3. The system of claim 1 , further comprising:
a first pigment comprising a plurality of first particles,
one of the plurality of first particles comprising the first interference filter; and
a second pigment comprising a plurality of second particles,
one of the plurality of second particles comprising the second interference filter.
4. The system of claim 3 ,
wherein the first pigment is dispersed in a carrier forming a first intaglio ink, and
wherein the second pigment is dispersed in a carrier forming a second intaglio ink.
5. The system of claim 1 , wherein the first reflector layer and the second reflector layer comprise a reflector material.
6. The system of claim 5 , wherein the reflector material is Aluminum.
7. The system of claim 1 , wherein the first spacer layer and the second spacer layer comprise a spacer material.
8. The system of claim 1 , wherein the light-absorber material is Chromium.
9. The system of claim 1 , wherein the first interference filter and the second interference filter match in hue, chroma, and lightness at a normal viewing angle.
10. The system of claim 1 ,
wherein the optical thickness of the first spacer layer is n QWOT at a λ wavelength,
wherein the optical thickness of the second spacer layer is k QWOT at the λ wavelength,
wherein n and k are integers that are different from one another and each equal to 2, 4, or 6, and
wherein the λ wavelength is between 400 and 700 nm.
11. The system of claim 1 , wherein a functional color match of the first interference filter and the second interference filter at the first viewing angle is dE<6 when a demarcation or distance between the first interference filter and the second interference filter is less than a particular demarcation or distance.
12. A system comprising:
a first interference filter; and
a second interference filter,
wherein the first interference filter comprises:
a first absorber layer having a thickness H1, and
a first spacer layer having a first optical thickness,
wherein the second interference filter comprises:
a second absorber layer having a thickness H2, and
a second spacer layer having a second optical thickness,
wherein the second optical thickness is different from the first optical thickness,
wherein the first interference filter and the second interference filter are separate structures,
wherein the first interference filter and the second interference filter appear to match in color at a first viewing angle,
wherein the first interference filter and the second interference filter appear to have different colors from each other at a second viewing angle,
wherein a difference in color between the first interference filter and the second interference filter at the first viewing angle is less than a difference in color at the first viewing angle between two interference filters forming a first comparison pair, different from the first interference filter and the second interference filter only in that absorber layers in the two interference filters of the first comparison pair have the thickness H1, and is less than a difference in color at the first viewing angle between two interference filters forming a second comparison pair, different from the first interference filter and the second interference filter only in that absorber layers in the two interference filters of the second comparison pair have the thickness H2, and
wherein the second viewing angle is different from the first viewing angle.
13. The system of claim 12 , wherein the second viewing angle is different from the first viewing angle by more than 10 degrees.
14. The system of claim 12 , wherein the first interference filter further comprises a first reflector layer.
15. The system of claim 14 , wherein the first spacer layer is between the first reflector layer and the first absorber layer.
16. The system of claim 12 , wherein the first absorber layer and the second absorber layer are partially light transmitting layers.
17. The system of claim 12 , wherein the first interference filter further comprises a first reflector layer that is between 60 to 1000 nm thick.
18. The system of claim 12 , wherein the first interference filter further comprises a first reflector layer with a reflectivity of higher than 60%.
19. The system of claim 12 ,
wherein the first interference filter further comprises a first reflector layer, and
wherein the second interference filter further comprises a second reflector layer.
20. The system of claim 19 , wherein the first reflector layer and the second reflector layer are opaque layers.
21. The system of claim 19 , wherein a first thickness of the first reflector layer is same as a second thickness of the second reflector layer.
22. The system of claim 12 , wherein a functional color match of the first interference filter and the second interference filter at the first viewing angle is dE<12 when there is a particular demarcation or distance between the first interference filter and the second interference filter.
23. The system of claim 12 , wherein a functional color match of the first interference filter and the second interference filter at the first viewing angle is dE<6 when a demarcation or distance between the first interference filter and the second interference filter is less than a particular demarcation or distance.