  We investigate the formation of particular patterns when light passes through
glass. Experimentally, we use various glass plates, registering each reflected
and transmitted outcome. Thus, we find the condition to form a common pattern,
namely, randomly scratched plates produce the halos. We engineer other optical
patterns by means of the specular holography method. Using the Defocusing
Microscopy technique, we study the geometric properties of the glass,
establishing the physical and mathematical model for a simulation. Our
computational results agree well with the experimental ones, leading us to
conclude that the pattern formation is governed by specular reflection on
various points along the scratches. Our findings give an initial explanation
for the pattern formation on glass, in particular for the halo design.
