Optical security device based on a surface of revolution

An optical article printed on a substrate, comprising:

• a plurality of reflective magnetic platelets,
• wherein the plurality of reflective magnetic platelets are aligned to exhibit a first reflective effect in a head-on view without rotating the substrate around an axis,
• wherein the plurality of reflective magnetic platelets are aligned to cause a second reflective effect in a different view,
• wherein the second reflective effect comprises a first lateral motion of a first portion of a reflection, of the first reflective effect, that is larger than a second lateral motion of a second portion of the funnel-shaped reflection, and
• wherein the different view is different from the head-on view without rotating the substrate around the axis.

An article comprising:

• a plurality of reflective magnetic platelets,
• wherein the plurality of reflective magnetic platelets are aligned to exhibit a funnel-shaped reflection in a first view,
• wherein the plurality of reflective magnetic platelets are aligned to cause a different reflective effect in a second view, and
• wherein the different reflective effect is different from the funnel-shaped reflection.