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Digital micromirror devices (DMDs), owing to their rapid refresh rates, are among the most commonly used spatial light modulators in holographic three-dimensional near-eye displays. However, the modulation of DMD is typically confined to binary amplitude modulation, resulting in a noticeable presence of zero-order and conjugate noise, which significantly occupies the spatial bandwidth of the display optics and reduces the quality of optical reconstruction. To address these issues, we propose a computational framework of generating optimized binary computer-generated holograms for DMD-based holographic near-eye displays. Our work employs an iterative-based optimization strategy within a band-limited diffraction computation, thereby enhancing the display quality while achieving a considerable field of view by eliminating zero-order and conjugate noise. The proposed method is verified experimentally by displaying true three-dimensional images with low speckle noise and high contrast, opening a path towards next-generation of virtual reality/augmented reality display devices. [ABSTRACT FROM AUTHOR]

We propose an approach for simultaneously shaping multiple three dimensional (3D) vector curve beams. The intensity distribution and polarization state variation of each 3D vector curve beam can be tuned along arbitrary prescribed trajectories. The scheme is based on the coaxial superposition of the orthogonally polarized 3D base vector curve beams through non-iterative holographic 3D beam shaping technique. In particular, the hybrid 3D vector curve beams array is also generated with identical depth range. The transversal position of each vector beam can be governed independently. Moreover, the multiplexing of 3D vector beams is realized with different depth ranges in the focal region along the beam propagation. The numerical results are identical to the experiments. This method will be benefit to the trapping and transportation of particles. • A method of non-iterative holographic beam shaping for generating 3D vector curve beams along arbitrary trajectories. • Each individual 3D vector curve beam possesses tunable intensity and polarization state distribution. • Generation of multiple 3D vector curve beams in different depth range regions is experimentally investigated. [ABSTRACT FROM AUTHOR]

In this paper, we present an approach for creating a polarization singularity array (PSA) along a curvilinear structure by exploring a scheme of coaxially superposing pre-designed component vector beams. Each component vector beam independently and azimuthally modulates inhomogeneous polarization distribution based on a combination of holographic beam shaping techniques and vector beam generation schemes such that the polarization singularity lattice arranged in a tunable curvilinear structure and locations appear after the superposition of component vector beams. The proposed PSA is proven optically in the vector beam generator system, which is based on a multiplex computer-generated hologram. [ABSTRACT FROM AUTHOR]

Abstract A method of color holographic display from computer-generated cylindrical hologram (CGCH) based on radial-division is proposed. A single phase-only CGCH is calculated by using a multi-cylindrical surface (MCS) based iterative algorithm. This algorithm allows calculating a phase CGCH from red, green and blue components of a color object simultaneously. The radial distances for red, green and blue component objects are calculated according to the ratio of RGB wavelengths. When the hologram is illuminated by three laser beams of RGB colors, it can then reconstruct the wanted RGB components on the same radial position to obtain a color compound. Numerical simulation results demonstrate that simple 3D object can be reconstructed from single phase-only CGCH at the expected position. [ABSTRACT FROM AUTHOR]

We propose a method of efficiently calculating computer-generated hologram for holographic stereoscopic display. The stereoscopic hologram is generated by sequentially tiling all the hogels that are calculated from respective parallax intensity and depth maps based on nonuniform sampled wavefront recording plane (NS-WRP) algorithm. The whole computational procedure is simplified by diffraction calculation of hogels from 2D planar images of each viewpoint, instead of massive 3D point-source. Numerical and optical experiments are carried out to confirm the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

We propose a method for generating an elliptic perfect vector beam (EPVB) by modulating the dynamic and geometric phases. It is theoretically demonstrated that the shape of the beam can be changed from circle to ellipse by setting the scale factor m of the dynamic phase, but the diameter of it is independent on the topological charge and the polarization order. Since the geometric phases provided by the dialectic Q-plate vary with the polarization state of the illumination beam, EPVB can be converted to the elliptic perfect optical vortex (EPOV) beam by changing the polarization state of the illuminating beam. Therefore, we also provide an alternative method to generate the EPOV beam. The experimental results agree well with the theoretical expectations. [ABSTRACT FROM AUTHOR]

We propose a method to calculate computer-generated hologram (CGH) from 3D object of arbitrary size and viewing angle. The spectrum relation between a 3D voxel object and the CGH wavefront is established. The CGH is generated via diffraction calculation from 3D voxel object based on the development of a scaled Fresnel diffraction algorithm. This CGH calculation method overcomes the limitations on sampling imposed by conventional Fourier transform based algorithm. The calculation and reconstruction of 3D object with arbitrary size and viewing angle is achieved. Both of simulation and optical experiments proves the validation of the proposed method. [ABSTRACT FROM AUTHOR]

A method of calculating computer-generated hologram (CGH) for color holographic 3D projection is proposed. A color 3D object is decomposed into red, green and blue components. For each color component, a virtual wavefront recording plane (WRP) is established which is nonuniformly sampled according to the depth map of the 3D object. The hologram of each color component is calculated from the nonuniform sampled WRP using the shifted Fresnel diffraction algorithm. Finally three holograms of RGB components are encoded into one single CGH based on the multiplexing encoding method. The computational cost of CGH generation is reduced by converting diffraction calculation from huge 3D voxels to three 2D planar images. Numerical experimental results show that the CGH generated by our method is capable to project zoomable color 3D object with clear quality. [ABSTRACT FROM AUTHOR]

Abstract: A new method of image projection based on fractional Fourier transformation is presented. This method can project an image at any distance after a lens plane. We use a modified Gerschberg–Saxton (GS) iteration algorithm to compute a phase-only hologram. The amplitude distributions both on the hologram plane and image plane are restricted while allowing their phase distributions to drift into an optimum value. The quality of the image projected by fractional Fourier hologram is close to the image projected by Fourier hologram. The RMS error between the projected image and the constrained image is computed in our experiment. A comparison in flexibility of the two projection methods is also discussed. [Copyright &y& Elsevier]

• A true 3D display mode without vergence and accommodation conflict is achieved. • A simple and one-step 3D wavefront diffraction calculation is proposed. • The computation cost of computer-generated holograms (CGHs) is low. • The holographic display optics maintains a very compact enclosure. • A high quality 3D reproduction with reduced coherent noise is achieved. We present an efficient method for the fast calculation of computer generated hologram (CGH). The 3D object is split into sub-layers according to its depth information. A 2D all-in-focus image is generated by sequential tiling all the layers in one plane. A Fourier hologram that contains all the information of 3D object is calculated from the fast Fourier transform (FFT) of the reassembled 2D image. By multiplying a pre-calculated multifocal off-axis digital phase mask (DPM) to the Fourier hologram, the content of each layer is axially relocated to different depth in the Fourier transform optical system to reconstruct the 3D object. The computation speed of the proposed method is greatly improved with only single FFT calculation process. Both of simulation and experimental results proves the validation of the proposed method. [ABSTRACT FROM AUTHOR]

We propose a method for generating the fractional elliptic perfect vector beam (EPVB) by superposition of a pair of orthogonal polarized ellipse perfect optical vortex with opposite fraction azimuthal index, in which we make a whole new spiral phase pattern that includes several angular sectors where the phase grows from 0 to π. The experimental method is based on vector optical field generator system in which the two orthogonally polarized ellipse perfect optical vortex are generated, and then superposed in coaxial way by a Ronchi grating. A phase-only computer-generated hologram to modulate the two desired ellipse perfect optical vortex is calculated and imprinted onto the SLM in order to perform the beam conversion. The experimental results are in line with our theoretical expectations. • We combine the fractional order with the ellipse perfect vector beams creatively. • We make several angular sectors where phase grows from 0 to π to replace the traditional fractional spiral phase. • We use two orthogonally polarized ellipse perfect optical vortex, and coaxial superpose them by a Ronchi grating. [ABSTRACT FROM AUTHOR]

We propose a method to generate arbitrary perfect Poincaré beams using one spatial light modulator (SLM). A polarization beam splitter is used to generate two polarization beams that are orthogonally (x and y) polarized. Half of the SLM helps shape the x-polarized beam; simultaneously, the other half of the SLM shapes the y-polarized beam. By adding different or the same spiral phases to the orthogonally polarized beams, any point on the Poincaré surface can be reached. The proposed approach is experimentally evaluated. The ring diameter remains the same when different polarization orders and topological charges are programmed. The generation of perfect Poincaré beams including fundamental Poincaré sphere, high-order Poincaré sphere, and hybrid Poincaré sphere are demonstrated in our system. [ABSTRACT FROM AUTHOR]

Abstract We propose an approach for imaging multi-plane-object where the image contents at different distant planes are recorded simultaneously in a single shot. The method is based on a compound quadratic distorted (QD) grating and the polarization multiplexing technique. The compound grating consists of two QD gratings with different parameters, which controls the distance interval between object planes. In polarization multiplexing technique, the images on x- and y- directions are modulated into orthogonally polarized, therefore the desired images can be selected by rotating the analyzer in the system. Two experiments are carried out to verify the proposed method. The first experiment is for the static samples, in which the distance interval between adjacent imaging planes can be changed from mm to μ m by controlling the parameters of two QD gratings and magnification of the imaging system. The second experiment is the imaging of dynamic samples of flowing yeasts in microfluidic tubes. From the recorded data, we calculate the velocity of flow particles. Both experimental results prove that the proposed method is capable of imaging 3D object consisting of unequal-distance-layers, which is of significance for potential applications in particles imaging and tracking. Highlights • A method of multi-plane imaging which allows the simultaneous imaging of multiple unequal-distance-object. • The polarization multiplexing technique makes the images on x- and y- directions orthogonally polarized. • Two experiments have been carried out to testify the proposed method in static and dynamic modes. [ABSTRACT FROM AUTHOR]