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US 8,211,596 B2Granted
Optically variable security device
AssigneeDe La Rue International Limited
InventorBrian William Holmes
Life of this patent
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Abstract
A method of forming a security device comprises: a) providing an undeveloped photoresist layer on an electrically conductive layer; b) forming a first diffractive pattern in the undeveloped photoresist layer using optical-interferometry; c) forming a second diffractive pattern in the undeveloped photoresist layer using electron beam lithography; and d) thereafter developing the photoresist layer.
Claims25
A method of forming a security device, the method comprising
- a) providing an undeveloped photoresist layer on an electrically conductive layer;
- b) forming a first diffractive pattern in the undeveloped photoresist layer using optical-interferometry;
- c) forming a second diffractive pattern in the undeveloped photoresist layer using electron beam lithography;
- and
- d) thereafter developing the photoresist layer.
2 more elements
Dependencies are inferred from the claim text.