Superposition of micropattern and microlens arrays for improved dynamic moiré pattern

Abstract

Layers of microlens array (MLA) and micropattern array (MPA) are integrated on a layer of polyester film, with the aim to give rise to a special dynamic pattern which can be observed without any visual facilities. In this paper, we propose an improved approach for obtaining a presentation of an individual dynamic moiré pattern rather than dynamic moiré patterns in an array. The improved dynamic moiré pattern can be amplified without size limitation and has different dynamic effects from the traditional dynamic moiré pattern, as it will appear and disappear with variation of the viewing angle. The principle of designing every elemental unit of the MPA is described. The differences between the improved method and the traditional method are compared, and how the improved dynamic moiré pattern works is explained in detail. The formulae describing the relationship between parameters of the improved dynamic moiré pattern and its microstructure are derived. In addition, relative experiments are conducted, and an improved dynamic moiré pattern of the expected size are achieved and validated. This microstructural device on film has potential applications in document security, packaging, and authentication.