The majority of contemporary optical encryption techniques use coherent illumination and suffer from speckle-noise pollution, which severely limits their applicability even when information encoded into special “containers” such as a QR code. Spatially incoherent encryption does not have this drawback, but it suffers from reduced encryption strength due to formation of an unobscured image right on top of the encrypted one by undiffracted light from the encoding diffraction optical element (DOE) in axial configuration. We present a new lensless encryption scheme, experimentally implemented with two liquid crystal spatial light modulators, that does not have this disadvantage because of a special encoding DOE design, which forms desired light distribution in the photosensor plane under spherically diverging illumination without a converging lens. Results of optical experiments on encryption of QR codes and successful information retrieval from decoded images are presented. Conducted analysis of encryption strength demonstrates sufficiently high key sensitivity and large enough key space to resist any brute force attacks.

Quick response (QR) codes have recently become a popular data container for optical encryption systems. Their effectiveness is based on the error-correction codes, that allow them to decode data even when the media itself is significantly damaged. However, QR codes were developed for specific applications and have a significant number of elements that are superfluous for optical encryption. In this paper we present a new customizable digital data container (CDDC), designed to replace QR codes in optical encryption. CDDC is based on the error-correction codes too, but has a wide range of configurable parameters and can be specialized for a particular optical setup. The results of noise robustness analysis, numerical and optical experiments on application of the new container in a spatially incoherent optical encryption system demonstrate the supremacy of CDDC in comparison to QR codes in terms of error correction capabilities and data density.

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The necessity of the correction of errors emerging during the optical encryption process led to the extensive use of data containers such as QR codes. However, due to specifics of optical encryption, QR codes are not very well suited for the task, which results in low error correction capabilities in optical experiments mainly due to easily breakable QR code’s service elements and byte data structure. In this paper, we present optical implementation of information optical encryption system utilizing new multilevel customizable digital data containers with high data density. The results of optical experiments demonstrate efficient error correction capabilities of the new data container.

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