Mirrors normally reveal what is placed in front of them, even when their curvature distorts a reflection. Researchers at the University of California, Los Angeles (UCLA) have introduced a different optical concept: a “lying mirror” that hides information carried by an input image and transforms it into a misleading, ordinary-looking pattern at the output. The study is published in the journal Nature Communications.

The all-optical system combines a reflective mirror with an optimized structured diffractive surface. Instead of using a computer to digitally alter an image, the lying mirror performs the transformation through programmed light diffraction and passive light-matter interactions. Once the diffractive surface is designed and fabricated, the optical transformation that hides the input information requires no digital computation.