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We report on a novel state-of-the-art diffraction optical elements (DOE) based waveguide architecture for aug- mented reality (AR) display with increased field of view and method for analytical design of such an architecture. The effectiveness of the architecture results from the multiple usage of the same propagation directions inside the waveguide by different field of view parts. Unlike in previous solutions, where such approach would lead to crosstalk generation, the proposed architecture different field of view parts are propagated in different waveguide locations, separated by the corresponding DOEs. The architecture can be applied either for increasing the verti- cal field of view size or the horizontal field of view size with compensation of chromatic dispersion resulting from the diffraction. The architecture configuration, analytical derivations of the DOEs parameters, and modeling results are discussed. The architecture satisfies market demands for the form-factor, size and weight, as well as allows up to four times increase of the field of view size in comparison with the conventional solutions. For the DOEs refractive index of 1.5, the architecture provides 48x44 degrees white-light field of view within two waveguides and 56x56 degrees white-light field of view within three waveguides. For the DOEs refractive index of 1.9, the architecture provides 58x58 degrees white-light field of view within only one waveguide.

The fast quenching of CaF2 crystals preheated up to 1000 °C allows to stabilize the high-temperature disordering of anion sublattice typical for the superionic state of the crystal. Such procedure results in the formation of structured ultraviolet to vacuum ultraviolet (UV–VUV) absorption with a lengthy long-wavelength tail stretching into the visible spectral range. Such absorption in the quenched crystals cannot be related to any local center and testifies to the presence of nano-sized complexes of displaced anions, the electron structure of which is drastically changed as compared with a regular lattice. Possibly, these clusters are frozen dynamic clusters that were discovered earlier in the superionic state with quasi-elastic diffuse neutron-scattering technique. Four luminescence bands in near UV and visible spectral range correspond to four low-energy absorption bands. Unlike absorption bands that are of zone nature, the luminescence occurs from the localized state that arises due to strong electron-vibration coupling in the clusters. Absorption and luminescence states are divided by a potential barrier that is responsible for the spacing between corresponding excitation and emission bands as well as the temperature quenching of luminescence. The luminescence study reveals the features of the electronic structure of clusters within preheated/quenched CaF2 crystals. The quenching method allows to study the high-temperature superionic state of crystals with fluorite structure using a wide set of experimental techniques.

The influence of deviation of recording and reading conditions of multiplex Bragg gratings from calculated values on the parameters of restorable fan of beams of a holographic prism (HP) formed by Bragg gratings in photothermorefractive glass is analyzed. Deviations are specified either as a rotation of the sample around one of three orthogonal axes Oxyz or as simultaneous rotation of the sample around two axes. It is shown that errors in the sample installation do not affect quality of the HP in recording if all gratings are recorded with the same deviation from an ideal position. However, difference in errors at the recording of each grating results is a reduction of flatness of fan of the HP and a loss of its working capacity. Ultimate values of errors of rotation around the Ox and Oy axes allowing one to maintain HP functionality, i.e., simultaneous reconstruction of all its beams, are calculated. It is established that, in the case of an ideally recorded HP, errors in the stage of reading may result in twisting the fan and disrupting its flatness.

A technology for multivalued holographic measurement of a plane angle—a holographic prism, which serves as the basis for a device for calibrating the testing tools for navigational equipment under rolling— has been developed. The holographic prism is a miniature sample of photosensitive material, which contains a system of superimposed holographic gratings, and a laser the radiation of which passes through gratings to form a fan of diffracted beams. The fan in a prism based on a calcium fluoride (fluorite) crystal with color centers contained six out-of-plane beams radiating from a region with a hard-to-localize center. This fact hindered calibration of the measure and its application in the testing device. The use of photothermo-refractive glass as a material for preparing a sample and recording a system of holograms in it makes it possible to eliminate the drawbacks of fluorite-based prism. The number of holograms rises up to 21, the fan becomes in-plane, and its center is localized in a small region, with a size of several tenths of the sample thickness (1–2 mm). The fan beams are energetically homogeneous, and each can be identified when using the fan in a testing device.