Optical modeling of changeable laser image functionality with analysis of the viewing performance.

Changeable laser image is a security feature commonly used on personalized documents. To understand and to predict the influence of different design parameters, a holistic optical modeling approach is essential. In this work a two-stage modeling process is performed using geometric ray tracing methods. The first stage, based on a basic optical model, allows us to identify the influencing parameters and to determine optimum solutions. The second stage, based on an advanced model, allows us to evaluate the optimum performance quantitatively in terms of the viewing angles and the contrast between two images. Simulation results are verified by experiments.