Cryptographic Strain-Dependent Light Pattern Generators

TL;DR

This paper introduces 3D-printed, stretchable magic windows that generate cryptographic light patterns, such as micro-QR-codes, whose shapes can be dynamically changed and used for secure communication and anti-counterfeiting.

Contribution

It presents a novel method for creating strain-dependent, reconfigurable light pattern generators using 3D-printed, stretchable optical components for cryptographic applications.

Findings

Successfully projected and recognized micro-QR-codes with strain gating

Demonstrated cryptographic light patterns that are cryptic when unstrained

Enabled pattern decryption using coupled magic windows

Abstract

Refractive freeform components are becoming increasingly relevant for generating controlled patterns of light, because of their capability to spatially-modulate optical signals with high efficiency and low background. However, the use of these devices is still limited by difficulties in manufacturing macroscopic elements with complex, 3-dimensional (3D) surface reliefs. Here, 3D-printed and stretchable magic windows generating light patterns by refraction are introduced. The shape and, consequently, the light texture achieved can be changed through controlled device strain. Cryptographic magic windows are demonstrated through exemplary light patterns, including micro-QR-codes, that are correctly projected and recognized upon strain gating while remaining cryptic for as-produced devices. The light pattern of micro-QR-codes can also be projected by two coupled magic windows, with one of them acting as the decryption key. Such novel, freeform elements with 3D shape and tailored functionalities is relevant for applications in illumination design, smart labels, anti-counterfeiting systems, and cryptographic communication.