Holography is known to be a prospective tool for storing large amounts of digital information, providing long lasting safety and high speed data access. In this paper, we present a new approach to holographic memory system design. Our method is based on an application of discrete Fourier-transform calculations to encode two-dimensional binary data pages as computer-generated amplitude Fourier holograms (CGFHs). These CGFHs, represented as grayscale raster images, can be displayed with the use of a high resolution amplitude spatial light modulator (SLM) in an optical projection system and exposed on holographic medium with multiple reduction. The optical scheme required for the technical realization of this method appears significantly simpler compared with known holographic memory recording devices; moreover, it can be built using either coherent or incoherent light sources. Coding of data pages by precise pseudorandom phase masks during CGFH synthesis allows us to achieve about 3% of the recorded microholograms diffraction efficiency. The experimental results of CGFH projection recorded with a $20\times$ reduction on photosensitive holographic medium and its reconstruction are presented.

Subject of study. An overview of modern neural-network-based methods for digital and computer-generated holography is presented. Relevant works on phase and amplitude reconstruction, media characterization, phase unwrapping, computer hologram generation, and related topics are discussed. Aim of study. The study investigates modern neural-network-based methods for digital and computer-generated holography. Method. The methods discussed in this review are based on neural networks and are developed for specific tasks in holography. Training datasets for supervised learning typically contain a set of input images (e.g., digital holograms, wrapped phase, 3D-scenes) and a set of target images (e.g., reconstructed scenes, unwrapped phase, 3D-holograms). The network learns to generate the target images from the input images during training. In unsupervised learning, there is no need to prepare target images; the training is based solely on the input images and the transformations applied to them. Main results. This review provides an overview of the applications of neural networks in holography, focusing on state-of-the-art works. It discusses the neural network architectures most commonly used in holography, organizing cited works based on their particular applications. The review highlights the most significant results and achievements of neural-network-based methods for digital and computer-generated holography. Practical significance. This review may interest researchers specializing in holography or adjacent fields. It familiarizes readers with modern neural-network-based methods used in computer hologram generation and holographic image reconstruction, as well as the specifics of their practical applications. The data presented demonstrate that neural-network-based methods can sometimes offer advantages in speed and/or quality compared with conventional methods.

The present article is dedicated to the problem of computer-generated holograms application for measurement of optical wavefront curvature with high precision. A holographic wavefront sensor scheme based on a phase-only spatial light modulator, which is used for CGH displaying, is proposed. The presented optical scheme and processing algorithm are validated with numerical simulations and experimental modelling.

The possibilities of designing optical devices for data processing and imaging based on the manipulation of coherent light beams by means of spatial light modulators (SLMs) are investigated. A review of commercially available SLMs is presented and the limitations of their complex modulation characteristics are analysed. The main problem of using present-day SLMs is the lack of the ability to modulate directly all states within a unit circle in the complex plane. In this regard, the characteristics of current methods for the synthesis of holographic elements are described that implement a given complex impulse response of the optical system and are optimal for using SLMs with purely amplitude, purely phase, and hybrid amplitude – phase modulation.