Crane Currency put a million microlenses on the $100 bill to make a tilting 3-D ribbon

NPR reported in 2017 that Crane Currency's engineer Sam Cape was shown a micro-optics prototype in 2005 that looked like three-dimensional film. He later led the research and development that turned it into the motion technology woven into every US $100 bill since 2013.

Each of the newest $100 bills uses nearly 1 million lenses, about a dozen to the tip of a human hair, that magnify microimages beneath them. On the blue ribbon next to Franklin's portrait, Liberty Bells seem to change into the numeral 100, and move up and down or left and right depending on the tilt direction.

The Bureau of Engraving and Printing's director said counterfeiting now relies on scanners and printers, and some security features are meant to be read by machines. He also called the cotton-linen currency paper itself one of the most effective features.

Make the security feature an optical effect that a scanner can't copy and a person can check in one tilt.

A scanner or printer sees one fixed viewpoint, so it can't reproduce the shifting image.

The effect is checked in a second by tilting the note.

The note is one of more than a dozen features, including color-shifting ink and a UV-glowing thread.

Microscopic lenses can be built into the note at production scale.

Defeat copying by building a feature whose behavior depends on viewing angle, not on a printable pattern.

Cape said Crane's motion technology is used on more than 100 denominations worldwide, and larger images and short animations are in the pipeline. The NPR piece is a company-sourced profile and gives no counterfeiting statistics showing how well the feature works.