Approximate magnitude of the bit rate of various telecommunications devices based on their year of introduction. Starting with the optical telegraph (or Chappe semaphore) presented to Napoleon Bonaparte in 1798, with a typical transmission speed of about 2 to 3 symbols (196 different types) per minute, or 0.4 b / s. Followed by the electric telegraph, popularized in the early 1840s using Samuel Morse’s code, reaching a rate of around 100 bps. Graham Bell’s telephone was introduced in 1876 and supported transmission of voice frequencies up to 64 kbps. The first NTSC black-and-white electronic television, available in the 1940s, had 525 interlaced lines and displayed images at a rate of 29.97 fps at a rate of 26 Mb / s7. The NTSC color format was introduced 10 years later and has tripled the black and white bandwidth to accommodate the red, green, and blue channels. More recently, the digital video format makes it easier to establish the bit rate according to the number of pixels (excluding compression) with HDTV [email protected] Gb / s in 1990, ultra-HDTV 2160p (4K) @ 12.7 Gb / s in 2010, and currently 4320p (8K) @ 47.8 Gb / s. 3D holographic displays are expected to have a data rate of 3 × 1015 bps, and by extrapolation of previous technology, it is predicted that they will emerge commercially by 2100. Credit: by Pierre-Alexandre Blanche
The pioneers of holography (Gabor, Leith, Upatnieks and Denisyuk) predicted early on that the ultimate 3D display would be based on this technique. This belief was rooted in the fact that holography is the only approach that can render all optical cues interpreted by the human visual system. 3D holographic displays have been a dream pursued for many years, facing challenges on all fronts: compute, transmission and rendering. With numbers like 6.6 × 1015 flops required for calculations, data rates 3 × 1015 b / s and 1.6 × 1012 phased pixels, the task was arduous.
In a new review article published in Light: Science and application, Professor Blanche of the University of Arizona reviews recent achievements in the field of 3D holographic display; in particular, new developments in machine learning and neural network algorithms demonstrating that computer-generated holograms approach real-time processing. A section of the document also deals with the problem of data transmission which can arguably be solved by using intelligent compression algorithms and fiber optic transmission lines. Finally, it introduces the final hurdle to 3D holographic display, which is the rendering hardware. However, there is no longer a mystery. With larger and faster spatial light modulators (SLMs), holographic projection systems are constantly improving. The number of pixels on liquid crystal-on-silicon (LCoS) phase displays as well as on microelectromechanical systems (MEMS) is increasing by the millions, and new photonic integrated circuit phase arrays are making real progress. It is only a matter of time for these systems to leave the laboratory and enter the world of consumption.
Holography is still regarded as the ultimate technology that will render all the optical clues necessary for the human visual system to see projected images in 3D. All other technologies, such as (auto) stereoscopy, light field or volumetric displays suffer from tradeoffs that limit 3D rendering. Nonetheless, these technologies will likely prove to be stepping stones leading to better visual comfort until the holographic displays are realized.
Some of the doors that kept holographic television from being made possible only a few years ago have already been unlocked. The rapid calculation of 3D holograms to properly control occlusions and parallax is now within reach as well as a solution to the problem of data transmission. The exact network architecture (thick or thin client) is unclear, but higher compression rates and ever faster telecom infrastructure supporting mobile internet communications make streaming data for holographic TV achievable. , even accessible.
However, some challenges remain to be resolved. The two main obstacles at the time of writing this manuscript are the computation of photorealistic 3D holograms within a reasonable timeframe and a suitable electronic device for the reproduction of large 3D holographic images at high resolution.
Pierre-Alexandre Blanche, Holography and the future of 3D display, Light: advanced manufacturing (2021). DOI: 10.37188 / lam.2021.028
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The future of 3D display and the emergence of holographic television (2021, December 27)
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