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

The control of luminous radiation has extremely important implications for modern and future technologies as well as in medicine. In this Review, we detail chemical structures and their relevant photophysical features for various groups of materials, including organic dyes such as metalloporphyrins and metallophthalocyanines (and derivatives), other common organic materials, mixed metal complexes and clusters, fullerenes, dendrimeric nanocomposites, polymeric materials (organic and/or inorganic), inorganic semiconductors, and other nanoscopic materials, utilized or potentially useful for the realization of devices able to filter in a smart way an external radiation. The concept of smart is referred to the characteristic of those materials that are capable to filter the radiation in a dynamic way without the need of an ancillary system for the activation of the required transmission change. In particular, this Review gives emphasis to the nonlinear optical properties of photoactive materials for the functi...

Nonlinear Optical Materials for the Smart Filtering of Optical Radiation.

5.3.2. Traps and Grating Dark Decay 3288 5.3.3. Other Concerns 3288 6. New Photorefractive Materials 3289 6.1. Polymer Composites 3289 6.2. Organic Amorphous Glasses 3292 6.3. Fully Functionalized Polymers 3294 6.4. Polymer-Dispersed Liquid Crystals 3295 6.5. Other Liquid Crystal-Containing Materials 3296 6.6. Near-Infrared-Sensitive Materials 3297 6.7. Other Materials Directions 3298 6.7.1. Hybrid Organic−Inorganic Composites and Glasses 3298

Organic photorefractives: mechanisms, materials, and applications.

We report the first results of ultra-fast enhanced light emission from gold– and silver–dendrimer nanocomposites. There is a fast (70 fs) fluorescence decay component associated with the metal nanocomposites. Anisotropy measurements show that this fast component is depolarized. The enhanced emission is suggestively due to local field enhancement in the elongated metal–dendrimer nanoparticles.

/pdf/ultrafast-time-resolved-photoluminescence-from-novel-metal-3lkl7c8vqg.pdf

Ultrafast time-resolved photoluminescence from novel metal–dendrimer nanocomposites

Fabrication of {198Au0} radioactive composite nanodevices and their use for nanobrachytherapy

The purpose of this paper is to discuss the general unclassified requirements for optical limiting devices and materials that might be used to protect U.S. military personnel and equipment from damaging laser radiation. Many researchers who consider working in this area are not familiar with the basic requirements that the U.S. military have for any material or device that would be fielded. This paper will attempt to set a general guideline for researchers in the field.

General optical limiting requirements

A definitive demonstration of the use of a photorefractive crystal to project a three-dimensional image in space is reported on The image is bright and different perspective views of the object appear as the viewing direction is changed

Three-dimensional image reconstruction using strontium barium niobate

Three-dimensional (3D) color holograms are recorded in a cerium-doped, strontium barium niobate (SBN:60) photorefractive crystal. These holograms are shown to reconstruct true color reproductions of the original object with an observable field of view of 37°. Angle multiplexing of two or more 3D color holograms is also demonstrated with angle tuning of the reference beam corresponding to a separation angle between stored images of 0.082°. Each of these results is compared with corresponding theoretical predictions.

Three-dimensional color holographic display.

Dendrimer metal nanocomposites are novel hybride materials that display unique physical and chemical properties as a consequence of the atomic/molecular level dispersion of inorganic and organic molecules. In their synthesis, dendrimers are used as templates to pre-organize metal ions followed by an in-situ reduction, which will immobilize and stabilize atomic domains of the reaction product(s). Size, shape, size distribution and surface functionality of these nanocomposites are determined and controlled by the dendritic macromolecules and may also be influenced by the encapsulated compounds. Solubility of these molecular nanocomposites is controlled by the polymer. Thus, it is possible to solubilize conventionally insoluble inorganic compounds in water or other solvents using dendritic hosts. Conceptually, these materials have enormous potential for applications such as catalysts or molecular devices. In this work, surface-modified poly(amido-amine) dendrimers were used to prepare (Cu(0)-PAMAM), (Ag(0)-PAMAM) and (Au(0)-PAMAM) dendrimer-metal nanocomposites containing stable and solvent soluble zero valence metals. Characterization of the resulting nanocomposites has been carried out by TEM, UV-visible spectroscopy, and scattering techniques. Depending on the chemistry of ion preorganization in the dendrimer, internal (“I”), external (“E”) and mixed (“M”) type nanocomposite structures could be identified according to the varying location of the actual metal content. The effect of structural differences was found to be reflected in the optical properties of the nanocomposites.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S1946427400165091

Dendrimer-Metal Nanocomposites

We report on a definitive demonstration of a 3D holographic display utilizing a photorefractive crystal. The resultant holographic image is viewed in real-time over a wide perspective, which can be extended by a mosaic of crystals. The image is also free from system-induced aberrations and has a uniform high quality over the entire range of FOV angles. The enhanced image quality results from the use of a phase-conjugate read beam generated from a second photorefractive crystal acting as a double-pumped phase- conjugate mirror. Multiple 3D images have been stored in the crystal via wavelength and angle multiplexing.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Brian P. Ketchel

Papers

General optical limiting requirements

Three-dimensional image reconstruction using strontium barium niobate

Three-dimensional color holographic display.

Dendrimer-Metal Nanocomposites

Three-dimensional holographic display using a photorefractive crystal