English to French Tech/Engineering Patents (in a patent) a security device for bank notes

Whilst this has certain advantages in that larger lenses can be used thereby enabling more complex images and effects to be produced, the disadvantage of such a configuration is that the feature occupies real estate on both sides of the polymer bank note and yet enables imagery to be projected from one side of the polymer bank note only. That is, the micro-optical effects are typically only able to be viewed from one side of the banknote, namely the side with the lenses even though they occupy space on both sides of the substrate.

Furthermore, the real estate occupied by the image elements typically cannot be overprinted with typical bank note design artwork because to do so would compromise the appearance of the optical effects, viewable from the lens side only.