A practical method of producing truly three-dimensional images that do not require the viewer to wear special eyewear would have many potential applications - in telemedicine, mapping and entertainment, for instance. True 3D holographic displays have so far lacked the capability of updating images with sufficient speed to convey movement. Now, a team working at the University of Arizona's College of Optical Sciences and Nitto Denko Technical Corporation in Oceanside, California, has developed a system that updates images at close to real-time. In a proof-of-concept experiment, they adapt an established technique based on holographic stereographic recording and a novel photorefractive polymeric material as the recording medium to produce a holographic display that can refresh its images every two seconds. Multicoloured and full parallax display are possible in this system - as is 3D 'telepresence', in which data describing holographic images from one location are transmitted to another location where the images are 'printed' with the quasi-real time dynamic holographic display. Holographic displays can produce truly three-dimensional (3D) images, but have so far been unable to update images fast enough. These authors have adapted a previous technique, based on holographic stereographic recording with a photorefractive polymeric material as the recording medium, to produce a quasi-real-time holographic display that can refresh its images every two seconds, and use it to demonstrate the possibility of 3D telepresence. Improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment. Holography is a technique that is used to display objects or scenes in three dimensions. Such three-dimensional (3D) images, or holograms, can be seen with the unassisted eye and are very similar to how humans see the actual environment surrounding them. The concept of 3D telepresence, a real-time dynamic hologram depicting a scene occurring in a different location, has attracted considerable public interest since it was depicted in the original Star Wars film in 1977. However, the lack of sufficient computational power to produce realistic computer-generated holograms1 and the absence of large-area and dynamically updatable holographic recording media2 have prevented realization of the concept. Here we use a holographic stereographic technique3 and a photorefractive polymer material as the recording medium4 to demonstrate a holographic display that can refresh images every two seconds. A 50 Hz nanosecond pulsed laser is used to write the holographic pixels5. Multicoloured holographic 3D images are produced by using angular multiplexing, and the full parallax display employs spatial multiplexing. 3D telepresence is demonstrated by taking multiple images from one location and transmitting the information via Ethernet to another location where the hologram is printed with the quasi-real-time dynamic 3D display. Further improvements could bring applications in telemedicine, prototyping, advertising, updatable 3D maps and entertainment.

Holographic three-dimensional telepresence using large-area photorefractive polymer

A high-efficient computer-generated integral imaging (CGII) method is presented based on the backward ray-tracing technique. In traditional CGII methods, the total rendering time is long, because a large number of cameras are established in the virtual world. The ray origin and the ray direction for every pixel in elemental image array are calculated with the backward ray-tracing technique, and the total rendering time can be noticeably reduced. The method is suitable to create high quality integral image without the pseudoscopic problem. Real time and non-real time CGII rendering images and optical reconstruction are demonstrated, and the effectiveness is verified with different types of 3D object models. Real time optical reconstruction with 90 × 90 viewpoints and the frame rate above 40 fps for the CGII 3D display are realized without the pseudoscopic problem.

High-efficient computer-generated integral imaging based on the backward ray-tracing technique and optical reconstruction.

Organic holographic materials such as photorefractive polymers are one of the promising candidates for the next generation three dimensional (3D) real-time display. Recently, we found that polymer composite of monolithic organic compound of 3-[(4-nitrophenyl)azo]-9H-carbazole-9-ethanol (NACzE) (30 wt%) doped transparent polymethylmethacrylate (PMMA) had capability of recording and displaying new images within a few seconds and fixed at ten seconds and viewing for a longer time without applying electric field. Here, we present 3D holographic display using monolithic organic compound NACzE dispersed transparent PMMA film sandwiched between two glass plates with size of 7.5 × 5 cm2. The thickness of film is ca. 50 μm. Images are easily and completely erased by over recording and it is accelerated by slight heating.

Real-time three-dimensional holographic display using a monolithic organic compound dispersed film

The modulation function of holographic functional screen (HFS) in the real-time, large-size full-color (RLF), three-dimensional (3D) display system is derived from angular spectrum analysis. The directional laser speckle (DLS) method to realize the HFS is proposed. A HFS by the DLS method was fabricated and used in the experiment. Experimental results show that the HFS is valid in the RLF 3D display, and that the derived modulation function is valuable for the design of the HFS. The research results are important to realize the RLF 3D display system which will find many applications such as holographic video.

The modulation function and realizing method of holographic functional screen

Light field visualization has progressed and developed significantly in the past years. At the time of this paper, light field displays are utilized in the industry and they are commercially available as well. Although their appearance on the consumer market is approaching, many potential applications of light field technology have not yet been addressed, such as video streaming. In this paper, we present our research on the dynamic adaptive streaming of light field video. In order to evaluate the presented concept of quality switching, we carried out a series of subjective tests, where test participants were shown light field videos containing stallings and switches in spatial and angular resolution.

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Evaluation of the Concept of Dynamic Adaptive Streaming of Light Field Video

A large-size and full-color three-dimensional (3D) display system without the need for special eyeglasses is demonstrated. With a specially fabricated holographic functional screen with a size of 1.8×1.3 m2, the system including optimally designed camera-projector arrays and a video server can display the fully continuous, natural 3D scene with more than 1 m image depth in real time. We explain the operating principle and present experimental results.

Demonstration of a large-size real-time full-color three-dimensional display

Two new concepts are deduced—those of hoxels and spatial spectrum by vector expression of four-dimensional Fourier transform integrals of the wave function or probability amplitude of any quantized energy probability distribution sampled by photons of this nature. Spatial spectrum collecting and recovering processes through hoxels by camera–projector arrays and holographic functional screens are proposed in detail to recover this three-dimensional holographic nature as a reinvention of holography. A real-time holographic display by simple aggregation of a digital camera–projector array is demonstrated as a rudimentary holographic television by holographic concepts, but without the need for coherent interference, as in conventional holography, or the encoded spatial frequency pattern of digital holography.

Use of spatial spectrum of light to recover three-dimensional holographic nature

In this chapter, the authors examine the concept of 3-D displays with sampled spatial spectra in discrete hoxels, reducing the redundancy present in digital holography, which prints each individual hogel. The underlying theory deals with the principles of 3-D imaging using the quantum model and 4-D (x,y,z,t) Fourier transforms. The image information is treated as a single spatial spectrum and its 3-D information recovered by digital vector treatment through hoxels. This enable the achievement of real-time communication in 3-D.

The Reinvention of Holography

A novel method for perfect holographic display by means of lens array and holographic functional screen is proposed. The process of acquisition, coding, restoration and display is described in detail.A holo-video system based on commercial 4K displayer is demonstrated as the result.

C. C. Jiang

Papers

Demonstration of a large-size real-time full-color three-dimensional display

The modulation function and realizing method of holographic functional screen

Use of spatial spectrum of light to recover three-dimensional holographic nature

The Reinvention of Holography

Demonstration of perfect holographic display on commercial 4K plane displayer