To enhance the complexity of the output sequence of the optical injection structure and improve the security of the bit plane encryption, this work proposes an image encryption algorithm based on optical chaos and quadrature amplitude modulation (QAM)-like. The external disturbance generated by the mutual injection of the dual-drive laser improves the complexity of the optical chaos output from the laser in the optical injection structure. In the image encryption algorithm, this work adopts a QAM-like coding mode, which encrypts the pixel value of the plaintext image by transforming the coordinates of the QAM constellation diagram and the coding. In the coding stage, the different coding modes of QAM-like are selected using the encryption sequence composed of optical chaotic sequence and key to transform the color plaintext image into the coded image, and the pixel value of the plaintext image is changed. In the scrambling stage, the encrypted sequence is used to scramble the multi-dimensional rows and columns of the three-dimensional coded image, and the position information of the pixel points is encrypted. In the diffusion stage, the scrambled images of each color component are diffused by GF(17) multiplication and finally merged to generate ciphertext images. Simulation results show that the proposed image encryption algorithm has sufficient key space and information entropy is close to the theoretical maximum, which can effectively resist known plaintext attacks, selective plaintext attacks, and statistical feature attacks.

Volume holographic optical elements (vHOEs) are currently used in various applications, such as augmented reality displays or wearables. Yet, the use of vHOEs as illumination optics has not found its way into products. In automotive exterior lighting, vHOEs could enable unique styling, reduction of installation space, weight, and material. However, in headlamps, rear lamps, or signal lamps, several technical and conceptional challenges must be addressed. One of these challenges is to replace lasers, which are expensive and have high safety demands, by light emitting diodes (LEDs), which are widely used in the field of automotive lighting. The reconstruction of volume holograms with LEDs is straightforward for graphical holograms showing a three-dimensional scene. For automotive exterior lighting, however, the hologram is not just a design element, but in addition must feature a light distribution fulfilling all the legal requirements. The vHOE thus becomes the most important functional element of the lighting system projecting the light distribution without an additional lens. For instance, the low beam distribution must provide a sharp, asymmetric cutoff line and white color, which turns out to be difficult. We have developed an improved manufacturing technique of such vHOEs, using two spatial light modulators. We present the design, the holographic printer setup, and first experimental results of vHOE samples.