Three-dimensional color holographic display

Review of Organic Photorefractive Materials and Their Use for Updateable 3D Display

Photorefractive materials are capable of reversibly changing their index of refraction upon illumination. That property allows them to dynamically record holograms, which is a key function for developing an updateable holographic 3D display. The transition from inorganic photorefractive crystals to organic polymers meant that large display screens could be made. However, one essential figure of merit that needed to be worked out first was the sensitivity of the material that enables to record bright images in a short amount of time. In this review article, we describe how polymer engineering was able to overcome the problem of the material sensitivity. We highlight the importance of understanding the energy levels of the different species in order to optimize the efficiency and recording speed. We then discuss different photorefractive compounds and the reason for their particular figures of merit. Finally, we consider the technical choices taken to obtain an updateable 3D display using photorefractive polymer. By leveraging the unique properties of this holographic recording material, full color holograms were demonstrated, as well as refreshing rate of 100 hogels/second.

Super long viewing distance light homogeneous emitting three-dimensional display

Three-dimensional (3D) display technology has continuously been attracting public attention with the progress in today's 3D television and mature display technologies. The primary characteristics of conventional glasses-free autostereoscopic displays, such as spatial resolution, image depths, and viewing angle, are often limited due to the use of optical lenses or optical gratings. We present a 3D display using MEMS-scanning-mechanism-based light homogeneous emitting (LHE) approach and demonstrate that the display can directly generate an autostereoscopic 3D image without the need for optical lenses or gratings. The generated 3D image has the advantages of non-aberration and a high-definition spatial resolution, making it the first to exhibit animated 3D images with image depth of six meters. Our LHE 3D display approach can be used to generate a natural flat-panel 3D display with super long viewing distance and alternative real-time image update.

Viewing angle enhanced integral imaging display using two elemental image masks

A viewing angle enhanced integral imaging display using two elemental image masks is proposed. In our new method, rays emitted from the elemental images are directed by two masks into corresponding lenses. Due to the elemental image guiding of the masks, the number of elemental images for each integrated image point is increased, enhancing the viewing angle. The experimental result shows that the proposed method exhibits two times larger viewing angle than the conventional method with the same lens array.

Viewing-angle enhancement of speckle-reduced volume holographic three-dimensional display by use of integral imaging

In a conventional integral imaging system the viewing angle is limited by the f-number of the microlens. To overcome this limitation we employ a phase-conjugate beam to read out elemental images, which are stored in photorefractive volume holographic storage, while the rotating diffuser reduces the speckle noise. In the proposed system the viewing angle can be enhanced over the f-number limitation. Experimental results and discussions of viewing parameters are presented.