# Fast 3D Content Update for Wide-Angle Holographic Near-Eye Display  
[PERSON]  
Faculty of Mechatronics, Warsaw University of Technology, 8 Sw. A. Boboli Street, 02-525 Warsaw, Poland; [EMAIL_ADDRESS] (R.K.); [EMAIL_ADDRESS] (M.C. ); [EMAIL_ADDRESS] (J.M.-C.); [EMAIL_ADDRESS] (M.S.I.) [PERSON]  
Faculty of Mechatronics, Warsaw University of Technology, 8 Sw. A. Boboli Street, 02-525 Warsaw, Poland; [EMAIL_ADDRESS] (R.K.); [EMAIL_ADDRESS] (M.C. ); [EMAIL_ADDRESS] (J.M.-C.); [EMAIL_ADDRESS] (M.S.I.) [PERSON]  
Faculty of Mechatronics, Warsaw University of Technology, 8 Sw. A. Boboli Street, 02-525 Warsaw, Poland; [EMAIL_ADDRESS] (R.K.); [EMAIL_ADDRESS] (M.C. ); [EMAIL_ADDRESS] (J.M.-C.); [EMAIL_ADDRESS] (M.S.I.) M.S.Kozacki  
Faculty of Mechatronics, Warsaw University of Technology, 8 Sw.  
Holographic displays must be designed based on the parameters of human vision. From this perspective, an interesting group of solutions are the holographic near-eye displays [8]. They support binocular vision [9], and provide colored [10; 11] and speckle free images [12]. Moreover, near-eye holographic displays allow focusing on different distances without a vergence-accommodation problem [13], and provide the possibility of interactivity [14]. From the immersion perspective, an essential parameter of near-eye displays is the size of the field of view (FoV), which limits the size of the image that can be observed. There are two main solutions enabling wide-angle viewing: decreasing the SLM pixel size with a 4F imaging system [9], or employing spherical illumination [15]. However, one of the significant limitations of wide-angle displays is the lack of fast and high-quality holographic content generation capability. CGH methods allow for calculating the diffracted field from an object employing a computer [16]. This calculation is possible by simulating the virtual representation of three-dimensional objects, mainly by using point cloud or polygon approaches [17; 18]. Representation of objects based on the point cloud approach offers calculations with basic propagators, such as the Fresnel or Angular Spectrum (AS) methods [19]. The wavefield of every point is computed with the help of these basic propagators and added one by one at the hologram plane. However, the realistic representation of an object demands that the number of points is counted in the millions. Moreover, the requirement of wide-angle viewing implies that the object is much larger than the hologram size. Hence, calculation of a CGH based on the point cloud approach will demand a significant amount of time. With the aim of reducing the calculation time, methods such as the wavefront recording plane (WRP) [20] or the phase added stereogram (PAS) [21] can be employed. Although WRP algorithms can reduce time calculation, they are not well suited for wide-angle view because the size of the object is much larger than the size of the hologram [22]. On the other hand, Ref. [23] has shown that the based-PAS algorithm is well suited for fast calculation of wide-angle view CGHs with densely populated clouds and occlusion culling of unseen areas. Despite these advantages, the PAS algorithm is still a relatively slow tool for obtaining a single high-resolution CGH for online viewpoint change. To deliver end-to-end realistic perception, near-eye holographic displays should provide the capability of a continuous change of viewpoint, so that the spatial displacement between two consecutive viewpoints must be smaller than the size of the hologram. In the literature, the calculation of multiple viewpoints is based on the principle of Fourier hologram synthesis [17; 24; 25; 26; 27]. This approach allows an easy manipulation of the multiple view projections of the object in the frequency space [24; 27]. Nevertheless, these types of solutions are not suited for the dynamic nature of the near-eye holographic display. They are developed for small viewing angles and do not support continuous change of viewpoint as they require processing of large amounts of information. Recently, Refs.