<title>Direct-write method to create DOVIDs in metal surfaces</title>

Abstract

This paper describes a technology for creating Diffractive Optical Variable Image Devices directly into metals and other materials. This technology is called Direct DOVID. When creating submicron structures onto metal surfaces, two important problems have to be addressed: (1) heating of the surface and (2) diffraction limitation of light. The micro technology group of TNO Industrial Technology has solved these technological challenges by developing a breakthrough laser technology that writes very small structures directly in metals. The strictures (gratings), can be as small as 200 nm. The structures can be used as DOVIDs and can be built up from pixels where each pixel is a DOVID in itself. They can be made in such a way that they have unique properties. The developed technology is proprietary for TNO. The advantage of the Direct DOVID technology is that every individual DOVID can be engraved uniquely in a product and can be made unique. This is a high-tech technology, which is not commonly available. It also permits applying unique characteristics (like diffractive numbers, barcodes, remote readable codes). The first issue is important for efforts against product piracy (band protection), the second for controlling product flow (product identification) in efforts against product diversion (parallel trade). Unique and permanent marking of products becomes more and more important in efforts against product diversion.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.