We propose a full color computer generated holographic near-eye display (NED) based on white light illumination. The method inspired from color rainbow holography is used for calculation of 2D and 3D color holograms. The parameters of the color hologram calculation are designed based on the parameters of the spatial light modulator (SLM) with 4K resolution. A slit type spatial filter is designed in frequency domain to extract red, green and blue frequency components for full color display. A NED system including a white light source, an achromatic collimating lens, a 4K SLM, a 4f optical filtering system, and an achromatic lens as eyepiece is designed and developed. The main contribution of this paper is the first time to apply the rainbow holography concept to the dynamic full color NED with a compact display system. The optical experiments prove the feasibility of the proposed method.
We propose an optical method to eliminate pseudoscopic issue in the integral imaging three-dimensional (3D) display by using a transmissive mirror device (TMD) and a light filter. Object light rays passing through the TMD can form an undistorted and depth inverted real image. Therefore, the TMD can eliminate the pseudoscopic issue existing in the traditional integral imaging. However, two ghost images appeared in integral imaging using the TMD. After studying the causes of the ghost images, a light filter is designed and fabricated to eliminate the ghost images. Integral imaging using TMD is developed, and it presents a high quality 3D image without a pseudoscopic issue.
Color rainbow holography can realize color holographic 3D display without speckle noise under white light illumination. However, traditional color rainbow holograms used for high-resolution static color 3D display or near-eye color display are amplitude-type, resulting in low diffraction efficiency due to the presence of conjugate light. In this Letter, a phase-only color rainbow holographic near-eye display is demonstrated. The calculation of a phase-only color rainbow hologram is realized by combining a band-limited diffraction and a bi-directional error diffusion algorithm with high-frequency blazed gratings coded to control longitudinal dispersion. When the wavelength of illumination light is deviated from the designated wavelength of the hologram, only a certain wavefront aberration is caused, but there is no conjugate light. The phase-only color rainbow holographic near-eye display of both a 2D color image and a 3D scene are implemented by optical experiments. It has potential applications in head-mounted 3D augmented reality displays without vergence-accommodation conflict.
A fast computer-generated holographic method with multiple projection images for a near-eye VR (Virtual Reality) and AR (Augmented Reality) 3D display is proposed. A 3D object located near the holographic plane is projected onto a projection plane to obtain a plurality of projected images with different angles. The hologram is calculated by superposition of projected images convolution with corresponding point spread functions (PSF). Holographic 3D display systems with LED as illumination, 4f optical filtering system and lens as eyepiece for near-eye VR display and holographic optical element (HOE) as combiner for near-eye AR display are designed and developed. The results show that the proposed calculation method is about 38 times faster than the conventional point cloud method and the display system is compact and flexible enough to produce speckle noise-free high-quality VR and AR 3D images with efficient focus and defocus capabilities.
Directional backlights have often been employed for generating multiple view-zones in three-dimensional (3D) display, with each backlight converging into a corresponding view-zone. By designing the view-zone interval for each pupil smaller than the pupil's diameter, super multi-view (SMV) can get implemented for a VAC-free 3D display. However, expanding the backlight from a light-source to cover the corresponding display panel often needs an extra thickness, which results in a thicker structure and is unwanted by a near-eye display. In this paper, two wave-guides are introduced into a near-eye virtual reality (NEVR) system, for sequentially guiding more than one directional backlight to each display panel for SMV display without bringing obvious extra thickness. A prototype SMV NEVR gets demonstrated, with two backlights from each wave-guide converging into two view-zones for a corresponding pupil. Although the additional configured light-sources are positioned far from the corresponding wave-guide in our proof-of-concept prototype, multiple light-sources can be attached to the corresponding wave-guide compactly if necessary. As proof, a 3D scene with defocus-blur effects gets displayed. The design range of the backlights’ total reflection angles in the wave-guide is also discussed.