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Category: holograms – Page 21

Holographic imaging of electromagnetic fields using electron-light quantum interference

In conventional holography a photographic film can record the interference pattern of monochromatic light scattered from the object to be imaged with a reference beam of un-scattered light. Scientists can then illuminate the developed image with a replica of the reference beam to create a virtual image of the original object. Holography was originally proposed by the physicist Dennis Gabor in 1948 to improve the resolution of an electron microscope, demonstrated using light optics. A hologram can be formed by capturing the phase and amplitude distribution of a signal by superimposing it with a known reference. The original concept was followed by holography with electrons, and after the invention of lasers optical holography became a popular technique for 3D imaging macroscopic objects, information encryption and microscopy imaging.

However, extending holograms to the ultrafast domain currently remains a challenge with electrons, although developing the technique would allow the highest possible combined spatiotemporal resolution for advanced imaging applications in condensed matter physics. In a recent study now published in Science Advances, Ivan Madan and an interdisciplinary research team in the departments of Ultrafast Microscopy and Electron Scattering, Physics, Science and Technology in Switzerland, the U.K. and Spain, detailed the development of a hologram using local . The scientists obtained the electromagnetic holograms with combined attosecond/nanometer resolution in an ultrafast transmission electron microscope (UEM).

In the new method, the scientists relied on electromagnetic fields to split an electron wave function in a quantum of different energy states. The technique deviated from the conventional method, where the signal of interest and reference spatially separated and recombined to reconstruct the amplitude and phase of a signal of interest to subsequently form a hologram. The principle can be extended to any kind of detection configuration involving a periodic signal capable of undergoing interference, including sound waves, X-rays or femtosecond pulse waveforms.

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Solving a Math Problem Just Brought Holograms Closer to Reality

Holograms are a staple in science fiction, but creating ones detailed enough to have serious applications in the real world has proved difficult. While scientists have been slowly pushing the field of holographic projection forward, they haven’t been able to overcome a problem called cross-talk. However, in a recent paper published in Nature, they have been able to manipulate the shape of light to overcome this, thus allowing them to produce 3D holograms that are orders of magnitude clearer, larger, and more detailed.

What Are Holograms?

Simple holograms are 2D surfaces that produce the illusion of a 3D object when light is shined through it.

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Quality of laser beam shaping can be enhanced at no extra cost

Researchers from Osaka University have developed a technique for improving accuracy of laser beam shaping and wavefront obtained by conventional methods with no additional cost by optimizing virtual phase grating. The results of their research were published in Scientific Reports.

A high quality square flattop is in demand for various fields, such as uniform laser processing and medicine, as well as ultrahigh intensity laser applications for accelerators and nuclear fusion. Beam is key to realizing the laser’s potential abilities and effects. However, since beam shape and wavefront vary by laser, beam shaping is essential for producing the desired shapes to respond to various needs.

Static and adaptive beam shaping methods have been developed for various applications. With Diffractive Optical Element (DOE) as a static method, edge steepness and flatness are low and wavefront becomes deformed after shaping. (Figure 1 (a)) In addition, computer-generated hologram (CGH) as a typical adaptive method has the same difficulties.

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5G can make digital humans look real and turn real people into holograms

Holograms. Emotive, life-like digital human beings. Washing machine repairs directed from miles away.

The rollout of 5G wireless networks that will continue throughout 2019 and beyond promises a slew of new smartphones that will hum along much faster than the models they’ll eventually replace. But while zippier handsets compatible with the next generation of wireless are surely welcome, 5G’s potential extends beyond them.

Verizon, and some of the entrepreneurial startups it is working with, recently demonstrated a few of the fresh consumer and business experiences made possible or enhanced by 5G, at its 5G Lab in New York City, one of five such labs around the country.

Multichannel vectorial holographic display and encryption

Holography is a powerful tool that can reconstruct wavefronts of light and combine the fundamental wave properties of amplitude, phase, polarization, wave vector and frequency. Smart multiplexing techniques (multiple signal integration) together with metasurface designs are currently in high demand to explore the capacity to engineer information storage systems and enhance optical encryption security using such metasurface holograms.

Holography based on metasurfaces is a promising candidate for applications in optical displays/storage with enormous information bearing capacity alongside a large field of view compared to traditional methods. To practically realize holograms, holographic profiles should be encoded on ultrathin nanostructures that possess strong light-matter interactions (plasmonic interactions) in an ultrashort distance. Metasurfaces can control light and acoustic waves in a manner not seen in nature to provide a flexible and compact platform and realize a variety of vectorial holograms, with high dimensional information that surpass the limits of liquid crystals or optical photoresists.

Among the existing techniques employed to achieve highly desired optical properties, polarization multiplexing (multiple signal integration) is an attractive method. The strong cross-talk associated with such platforms can, however, be prevented with birefringent metasurfaces (two-dimensional surfaces with two different refractive indices) composed of a single meta-atom per unit-cell for optimized multiplexing.

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