Abstract

After a brief description of the threats which face the issuers of documents and valuable papers, the concept of thin film anticounterfeiting coatings proposed by the NRCC will be explained¹. The colorimetric considerations which govern the design of such devices will be reviewed. Typical coating designs suitable for use in transmission and in reflection will be discussed. Reflection coatings can be constructed with and without an integral black absorber coating. The need for geometric patterns in the anticounterfeiting coatings will be explained. Various methods for producing such logos will be proposed. Mention will be made of the various numerical tools developed for the design and investigation of single films and multilayers, their desensitization to construction errors and for the investigation of different process control strategies. During the duration of the project experiments were performed on the optical constants and non-optical properties of a number of metal and dielectric films considered for use in the anticounterfeiting coatings. These, and some of the processes and equipment investigated during the development of a prototype production facility, will be reviewed. Finally, some security and economic aspects of the devices will be considered.

© 1988 Optical Society of America