The limited space-bandwidth product of digital holography results in a trade-off between the field of view (FOV) and eye motion box (EMB) size. One potential approach to overcome this trade-off is to use a waveguide as a pupil expander. However, this approach has the constraint of generating only infinite depth images or 2D images, which can cause visual discomfort. To address this issue, a novel method that enhances the space-bandwidth product while providing a 3D image with full depth range is necessary. In this paper, we introduce a projection-type holographic display that combines a waveguide, a spatial light modulator, and a laser light source to display true 3D holographic images with an extended FOV. Experimental results demonstrate that this method effectively generates holographic 3D images with an FOV expanded 4 times in the horizontal direction compared to conventional methods.
Holographic Optical Elements (HOEs) have emerged as a pivotal technology in enhancing holographic Augmented Reality (AR) display systems. This paper presents an innovative approach that utilizes an off-axis arrangement with an HOE to secure a wide field of view up to 55°, making significant strides in volumetric reduction compared to conventional 4f filtering systems. However, a challenge arises from Bragg mismatch in the HOE, which creates aberrations. Our work proposes a method for compensating these aberrations on a voxel-by-voxel basis, substantially improving the quality of the holographic display. Limitations such as the 2mm maximum size of the eye box due to the diffraction limit of the spatial light modulator (SLM) are acknowledged, but we suggest potential solutions such as using the HOE substrate glass as a waveguide and incorporating an array of lenses with an eye tracker for pupil tracking. Our findings offer significant contributions to the holographic display technology landscape and suggest promising avenues for future research.
To measure object wave in digital holography, the phase-shifting technique is popular by changing the phase of the reference wave. A piezo actuator (PZT) is usually used as a device to shift the phase. In a case to obtain the phase information of color object with multiple wavelengths, four-step phase-shifting algorithm with quarter wavelength shift is not convenient since the amount of the phase shift is difference according to each wavelength. In this paper, the generalized four-step phase-shifting method is proposed and experimentally verified to obtain color digital hologram using an image sensor with a Bayer pattern for capturing interference pattern shifted phase by one PZT.
Depth extraction and recovery from the recorded image have been studied and applied in many fields such as biology, robotics, and computer vision. In some researches, the aperture in the imaging system is coded as a particular function in order to distinguish relative distances from the focal plane or recognize sampled points from the recorded image and the image captured through this coded aperture is useful to retrieve blurred images or acquire depth maps. These studies are associated with the shape of point spread function (PSF). In some approaches, diffraction-based engineered PSFs such as double-helix and cubic phase are applied to extract the depth information. In this paper, we propose a depth measurement method based on the optical analysis of the pupil function. It is well known that the PSF is represented as a Fourier transform of the product of pupil function and spherical phase in a coherent imaging system. Also, it is possible to estimate the intensity of the PSF corresponding to the distance of the object in an incoherent imaging system. Then the depth information is extracted from a snapshot image by inverse transform of the image.
Recently the technology of hologram receives a lot of interest owing to its advantages and many researches on hologram recordings have been actively studied. In some studies, digital hologram printing methods have lots of applications because of the ability to record large area hologram based on the technique of holographic stereogram. The holographic stereogram printing method records the hologram composed of hogels which are the unit of the hologram recorded at once. This method has advantages in flexibility of the size since it records the hologram hogel by hogel. In addition, the hologram printer records not only wavefront of real objects captured by charge coupled device (CCD) but also hologram patterns of virtual objects calculated by computer-generated hologram (CGH) algorithm. In previous systems, it is difficult to implement the hologram in high resolution because of the low numerical aperture of hogels. In this paper, we suggest the method of recording high-resolution hologram using binary wavefront pattern and discuss the optical modulation properties of the printed binary pattern.
Recently, various light-field displays with special structures have been suggested. Among them, the cylinder-shaped display has distinct advantages in providing 360-degree field of view. In this paper, we propose a cylindrical light-field display which consists of panoramic projection optics and a cylindrical screen with several long vertical narrow openings. The projected scene is imaged on the inner surface of the cylinder and the contents are watched through the slit on the side of the cylinder during it rotates. Therefore, horizontal-parallax-only light field is formed to display threedimensional contents inside of the cylinder.
Recently, super multi-view technology has been considered as one of the most popular research topic and many studies
have been done to improve the quality of such super multi-view display. In this paper, we present specific experiments
for human cognition. We designed our system for the special purpose that the human cognition of 3D contents is
examined. In comparison of the previous super multi-view displays, the number of views in our system can be
controlled. Our system has a great advantage that the effect of the number of views can be evaluated at the common
system. We can change the number of views, by changing the synchronization ratio which determines the speed of the
opening of the optical chopper and the refresh time of the DMD. We expect that this system will be useful for
understanding the principle of the human cognition for 3D display.
KEYWORDS: Digital micromirror devices, 3D displays, Light emitting diodes, Beam splitters, 3D image processing, Displays, Reflectivity, Optical design, Mirrors, Control systems
Three-dimensional (3D) display usually provides binocular disparity to observer. To construct 360degree table-top display, lots of views are required. In order to display a large amount of views to observer, time-multiplexing technique is applied. We suggest a new structure for view-sequential 360-degree table-top display system. In my system, a transmissive screen is used and digital micromirror device (DMD) image is projected on it. This system defines the direction of bundle of rays to configure the sequential view. It has some advantages resulting from the transmissive flat screen. When the transmissive screen is used instead of the reflective one, the light power efficiency is improved. Moreover, the arrangement of the pixel is more uniform when the screen is flat instead of a static conic screen. We construct a table-top display with about 288views around 360degree and its feasibilities are confirmed.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.