Abstract

Subject of study. An off-axis wide-aperture hologram focusing mirror and the distortions that occur during its recording and playback in augmented reality display circuits are studied. Aim of study. The aim is to experimentally determine the adequacy of the geometric optics approximation in the non-axial holographic focusing mirror modeling and determine the sources and types of distortion. Method. In the first stage, computer modeling in Zemax and in specially created programs based on MATLAB is used. A comparison of the distributions of local periods for holographic focusing mirror recording on finite thickness substrates and on an extremely thin substrate is made. In the second stage, an experimental study of the recorded holographic focusing mirror is carried out. Two playback schemes are considered: “from point to point” (the scheme of reconstruction is similar to the recording scheme) and a scheme with the virtual image reconstruction at infinity. The shapes and structure of the reconstructed focal points formed by the holographic focusing mirror are studied, and the images are projected directly onto the CMOS photodetector. Main results. It is defined that irreversible distortions occur during the reconstruction of the holographic high aperture lenses due to the substrates of finite thickness influence. Homocentric reference and signal beams are used for the holographic focusing mirror recording. In addition, it is defined that the virtual image reconstruction scheme causes considerable distortions. The approximation of geometric optics gives quite good results for describing the operation of non-axial holographic lenses in the schemes of augmented reality displays. However, it is necessary to consider the finite thicknesses of the substrates, as well as the shrinkage of the recording medium. Practical significance. The results of the study can be used in the development of compact wide-aperture augmented reality displays. The applied approximations allow us to use them in the practical development of optical systems for augmented reality displays. Considering the finite thicknesses of the substrates can improve the quality of the generated virtual image.

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