US 12,240,261 B2
Optical devices and methods of manufacture thereof
Brian Holmes, Basingstoke (GB); Frederic Fournier, Basingstoke (GB); and Maria King, Basingstoke (GB)
Assigned to DE LA RUE INTERNATIONAL LIMITED, Basingstoke (GB)
Appl. No. 18/271,337
Filed by DE LA RUE INTERNATIONAL LIMITED, Basingstoke (GB)
PCT Filed Jan. 11, 2022, PCT No. PCT/GB2022/050049
§ 371(c)(1), (2) Date Jul. 7, 2023,
PCT Pub. No. WO2022/148977, PCT Pub. Date Jul. 14, 2022.
Claims priority of application No. 2100327 (GB), filed on Jan. 11, 2021.
Prior Publication US 2024/0051324 A1, Feb. 15, 2024
Int. Cl. B42D 25/328 (2014.01); B42D 25/324 (2014.01); G03H 1/08 (2006.01); B42D 25/351 (2014.01)
CPC B42D 25/328 (2014.10) [B42D 25/324 (2014.10); G03H 1/0841 (2013.01); B42D 25/351 (2014.10); G03H 2001/085 (2013.01)] 19 Claims
OG exemplary drawing
 
1. An optical device that exhibits a variable optical effect upon illumination, the optical device having a diffractive structure comprising a first diffractive region and a second diffractive region; wherein
the first diffractive region is formed of a portion of a first full kinoform diffractive structure, wherein the first full kinoform diffractive structure contains a first complete phase function to produce an electric field propagating from a first image object and thereby encodes a first image, whereby the first diffractive region defines a perceived motion and depth of the first image upon tilting the device in the form of a replayed image of the first image; and
the second diffractive region is formed of a portion of a second full kinoform diffractive structure, wherein the second full kinoform diffractive structure contains a second complete phase function to produce an electric field propagating from a second image object and thereby encodes a second image, whereby the second diffractive region defines a perceived motion and depth of the second image upon tilting the device in the form of a replayed image of the second image; wherein
the first image is different from the second image;
the portion of the first full kinoform diffractive structure and the portion of the second full kinoform diffractive structure are such that the perceived motion and/or depth of the replayed first and second images upon tilting the device are different;
the first diffractive region and the second diffractive region are laterally separate;
each of the first diffractive region and the second diffractive region are discernible by the naked human eye; and
the optical device is a security device.