This paper introduces Firefly, an optical lithography origination system that has been developed to produce holographic masters of high quality. This mask-less lithography system has a resolution of 418 nm half-pitch, and generates holographic masters with the optical characteristics required for security applications of level 1 (visual verification), level 2 (pocket reader verification) and level 3 (forensic verification). The holographic master constitutes the main core of the manufacturing process of security holographic labels used for the authentication of products and documents worldwide. Additionally, the Firefly is equipped with a software tool that allows for the hologram design from graphic formats stored in bitmaps. The software is capable of generating and configuring basic optical effects such as animation and color, as well as effects of high complexity such as Fresnel lenses, engraves and encrypted images, among others. The Firefly technology gathers together optical lithography, digital image processing and the most advanced control systems, making possible a competitive equipment that challenges the best technologies in the industry of holographic generation around the world. In this paper, a general description of the origination system is provided as well as some examples of its capabilities.
The optical characteristics of Diffractive Optical Elements are determined by the properties of the photosensitive
film on which they are produced. When working with photoresist plates, the most important property is the
change in the plate's topography for different exposures. In this case, the required characterization involves a
topographic measurement that can be made using digital holography. This work presents a digital holography
system in which a hologram's phase map is obtained from a single recorded image. The phase map is calculated
by applying a phase-shifting algorithm to a set of images that are created using a digital phase-shifting/tilteliminating
procedure. Also, the curvatures, introduced by the imaging elements used in the experimental setup,
are digitally compensated for using a polynomial fitting-method. The object's topography is then obtained from
this modified phase map. To demonstrate the proposed procedure, the topography of patches exposed on a
Shipley 1818 photoresist plate by microlithography equipment-which is currently under construction-is shown.