Retroreflective Coating
Multilayer coating that includes optical elements with retroreflective effect.
It consists of several layers:
- layer with microlenses (microbeads);
- layer with graphic images;
- reflective layer.
When the coating is illuminated by parallel (coaxial) light beams, light semi-transparent images contrasting with the background are visualized (fig. 2). Microbeads focus the light beams so that reflected light returns towards the light source providing a clear visual perception of the image.
Fig. 1. Structure of retroreflective coating
a
b
c
d
Fig. 2. Netherlands. Travel document for aliens issued in 1995:
a — data page. Paper substrate; b — the same. Retroreflective image. Coaxial light; c — the same. Laminate. Surface microrelief; d — the same. The top layer consists of microbeads (marked with arrows). Cross-section