Translator Disclaimer
7 April 2000 Computer-generated holograms and diffraction gratings in optical security applications
Author Affiliations +
Abstract
The term 'computer generated hologram' (CGH) describes a diffractive structure strictly calculated and recorded to diffract light in a desired way. The CGH surface profile is a result of the wavefront calculation rather than of interference. CGHs are able to form 2D and 3D images. Optically, variable devices (OVDs) composed of diffractive gratings are often used in security applications. There are various types of optically and digitally recorded gratings in security applications. Grating based OVDs are used to record bright 2D images with limited range of cinematic effects. These effects result form various orientations or densities of recorded gratings. It is difficult to record high quality OVDs of 3D objects using gratings. Stereo grams and analogue rainbow holograms offer 3D imaging, but they are darker and have lower resolution than grating OVDs. CGH based OVDs contains unlimited range of cinematic effects and high quality 3D images. Images recorded using CGHs are usually more noisy than grating based OVDs, because of numerical inaccuracies in CGH calculation and mastering. CGH based OVDs enable smooth integration of hidden and machine- readable features within an OVD design.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Pawel J. Stepien "Computer-generated holograms and diffraction gratings in optical security applications", Proc. SPIE 3973, Optical Security and Counterfeit Deterrence Techniques III, (7 April 2000); https://doi.org/10.1117/12.382191
PROCEEDINGS
7 PAGES


SHARE
Advertisement
Advertisement
RELATED CONTENT

The research for a system of city photonics map based...
Proceedings of SPIE (August 20 2013)
Binary optics in the '90s
Proceedings of SPIE (March 01 1991)
Visual hologram security
Proceedings of SPIE (August 26 2004)
Computer-generated holograms on a CD-R disk
Proceedings of SPIE (June 29 2004)

Back to Top