The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 14, 2022
Filed:
Jul. 16, 2020
Hong Kong Applied Science and Technology Research Institute Company Limited, Hong Kong, CN;
Zeineb Ben Aziza, Paris, FR;
Xiaohan Wang, Hong Kong, CN;
Ting Hao, Hong Kong, CN;
Xiuling Zhu, Hong Kong, CN;
Kenny Chan, Hong Kong, CN;
Abstract
A multilayered optical security device has a resonant waveguide grating (RWG) layer on an under layer having a hologram. The RWG layer has plural RWGs for generating one or more patterns. Each RWG has first and second RWG portions, with diffraction gratings of different grating periods, for light coupling-in and coupling-out, respectively. Using the RWGs minimizes interference to a holographic image generated by the under layer. This advantage is especially useful when the holographic image carries digital data such as in digital holographic encryption where an encrypted hologram is used in the under layer. The digital data may contain biometric information such as a fingerprint. In each RWG portion of an individual RWG, scattering elements in a grating are curved to thereby enhance an angular tolerance in azimuthal angle during observing the patterns by an observer while the individual RWG is still selective in elevation angle.