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Unveiling the Future: Holograhy moving to Real-Time 3D Holograms on Your Smartphone

Introduction:

The marvel of 3D hologram technology has evolved from static, monochromatic images to dynamic, real-time displays that are now making their way onto smartphones. Our eyes, the sophisticated light detectors that capture the essence of the world around us, are now able to perceive and interact with three-dimensional holograms in the palm of our hands. This groundbreaking development is poised to reshape the way we perceive and interact with visual content, offering a glimpse into an immersive and dynamic digital future.

In this article, we delve into the journey of holographic technology, explore the mechanics behind real-time 3D holograms, and envision the vast applications and possibilities that this groundbreaking advancement brings.

The Evolution of Visual Perception:

Our eyes act as intricate light receptors, capturing rays bouncing off nearby objects to construct a dynamic impression of our surroundings. When we observe a three-dimensional object, such as an apple, light reflects off its surface into our eyes, allowing our brain to merge these reflections into a stereoscopic image. The magic happens when we move our heads; the light paths shift, altering the perception of color, brightness, and darkness on different parts of the object.

Photography’s Limitations:

While traditional photography revolutionized visual representation, it couldn’t replicate the realism of a scene. A photograph encodes only the brightness of each light wave, resulting in a flat, two-dimensional image. Moreover, photographs are frozen moments in time, capturing light that has long vanished. In contrast, holograms, like photographs, convey a sense of reality but are akin to photographic ghosts, perpetually alive and dynamic.

Decoding the Holographic Message:

The term “hologram” stems from the Greek words “holos” meaning “whole” and “gramma” meaning “message.” Essentially, a hologram is a complete picture, a whole message. The uniqueness of holograms lies in their creation process. Unlike traditional photographs that measure light intensity, holograms encode both the brightness and phase of each light wave. Phase, correlating to depth information, allows the retrieval of a full 3D shape, providing a truer depiction of parallax and depth within a scene.

The Art and Science of Making Holograms:

The concept of holography dates back to the mid-20th century when Hungarian-British physicist Dennis Gabor laid the foundation for holographic imaging. Over the years, hologram technology has progressed from static and monochromatic images to full-color, three-dimensional representations. While holograms have been utilized in various industries, including entertainment, medical imaging, and security, achieving real-time holographic displays on everyday devices remained a formidable challenge.

The interference of these beams on a photographic plate created a hologram, giving the illusion of depth. With advancements in coherent light sources (lasers), holography has become a popular technique for 3D imaging across various applications.

How holograms work - Explain that Stuff

One half of the beam bounces off a mirror, hits the object, and reflects onto the photographic plate inside which the hologram will be created. This is called the object beam. The other half of the beam bounces off another mirror and hits the same photographic plate. This is called the reference beam. This reference generates a hologram’s unique sense of depth. A hologram forms where the two beams meet up in the plate.

Hologram encodes both the brightness and phase of each light wave.  Phase specifies the position of a point within the wave cycle and correlates to depth of information, meaning that recording the phase of light scattered by an object can retrieve its full 3D shape, which cannot be obtained with a simple photograph. That combination delivers a truer depiction of a scene’s parallax and depth.

A three-dimensional (3D) image can be reconstructed from a hologram by utilizing the theory of diffraction of light. When the hologram is illuminated by the reference beam alone, the diffraction pattern recreates the wave fronts of light from the original object. Thus, the viewer sees an image indistinguishable from the original object.

Holograms are 3D images created by scattering light onto a 2D surface, but a person typically has to look directly at that surface in order to see the futuristic projections. Producing 3D images that people can see from any angle, even when someone walks all the way around the projection, is much trickier. “To see the light, it needs to scatter off of something and enter your eye,” Smalley told NBC News MACH in an email. “Getting that scattering to happen in thin air is difficult.”

For more detailed knowledge about holographic technology please visit: Holographic Technology: Bringing the Virtual World to Life

Holograms can be categorized into two main types: reflection holograms, commonly exhibited in galleries, display three-dimensional images near their surfaces by reflecting white incandescent light from a specific angle; recent advancements enable the creation of color reflection holograms mimicking the optical characteristics of the original objects. On the other hand, transmission holograms are viewed with laser light, often the same type used during recording, and transmit a sharp and deep virtual image when lit from behind. These holograms offer an immersive experience, allowing the observation of a full-size scene through a small hologram, with each broken piece still providing the entire perspective. Additionally, directing an undiverged laser beam backward through a transmission hologram can project a real image onto a screen, enhancing the versatility of holographic displays.

Applications Beyond the Illusion:

Holographic technology extends its reach to diverse fields, including biological imaging, air/water quality monitoring, and surface characterization. Holograms have proven valuable in detecting stress in materials, monitoring telephone credit cards, aiding fighter pilots with holographic displays, and archiving museum records. The versatility of holography in capturing and reproducing 3D information makes it a powerful tool across industries.

Digital holography

A significant step forward from analog holography is to record digitally the interference pattern with an electronic sensor and to reconstruct the object numerically, including the amplitude and phase information, with a computer. Digital holography (DH) is a technique in which a digital hologram that contains an object wavefront is recorded, and both 3D and quantitative phase images of an object are reconstructed using a computer .

Digital holography refers to the acquisition and processing of holograms with a digital sensor array typically a CCD camera or a similar device. Image rendering or reconstruction of object data is performed numerically from digitized interferograms. Digital holography offers a means of measuring optical phase data and typically delivers three-dimensional surface or optical thickness images. Several recording and processing schemes have been developed to assess optical wave characteristics such as amplitude, phase, and polarization state, which make digital holography a very powerful method for metrology applications.

Digital Holography and the Dawn of Real-Time 3D Holograms:

Digital holography marks a significant leap forward, enabling the recording and reconstruction of holograms using electronic sensors and computers. Recent developments leverage deep neural networks to enhance holographic reconstructions, making them nearly instantaneous and scalable to consumer-grade GPUs. Real-time 3D holography holds promise for applications in medical diagnostics, advertising, entertainment, education, and more.

How Real-Time 3D Holograms Work:

With the ubiquity of smartphones and their ever-advancing capabilities, researchers and tech enthusiasts have turned their attention to bringing holographic experiences to handheld devices. Unlike traditional holograms that rely on specialized equipment, real-time 3D holograms on smartphones promise accessibility and portability, opening up a world of possibilities for users.

The key to real-time 3D holograms lies in the integration of advanced optics, computational power, and the high-resolution displays found in modern smartphones. Unlike static holograms, real-time holographic displays can adapt and change rapidly, creating dynamic, interactive content. One approach involves using light field displays that reproduce the way light interacts with objects, allowing users to view holograms from different angles, just like real objects.

Recent advancements in electronic devices, including high-resolution image sensors, spatial light modulators (SLM), and powerful computers, have significantly improved the capabilities of holographic displays. A lensless SLM with high pixel density contributes to the creation of natural, colorful, and high-quality 3D motion pictures on holographic displays. Simultaneously, a pixel-dense lensless image sensor captures fine interference fringes digitally, and sophisticated computational algorithms, such as the Fresnel approach, paraxial transfer function approach, and compressed sensing, enable the numerical reconstruction of holographic images with high throughput. However, many of these methods require detailed knowledge about the experimental setup, such as laser wavelength and camera pixel pitch, and often involve computationally intensive autofocusing algorithms and additional steps like phase shifting and frequency domain filtering to enhance image quality by suppressing unwanted artifacts.

Applications of Real-Time 3D Holograms:

This holographic reconstruction technique holds immense potential across various fields, including microscopy, quantitative phase imaging, 3D particle and flow measurement, imaging biological specimens in 3D, secure 3D image encryption, 3D object recognition, tomographic imaging of amplitude and phase distributions, nanometer-accurate 3D surface shape measurements, ultrafast 3D optical imaging using pulsed lasers, and holographic 3D imaging employing a single photodetector. The versatility and applications of this approach mark a significant stride toward advancing holography in diverse scientific and technological domains.

  1. Enhanced Entertainment Experiences: Imagine watching a live concert or sporting event in holographic form on your smartphone. Real-time 3D holograms could revolutionize the entertainment industry by bringing performances to life in the palms of millions of viewers.
  2. Immersive Learning Environments: Education stands to benefit significantly from real-time holograms. Complex subjects could be explained through interactive, three-dimensional models, offering students a hands-on learning experience.
  3. Virtual Collaboration: Business meetings and collaborations could transcend video calls with the integration of real-time 3D holograms. Colleagues from around the world could virtually meet and interact in a shared holographic space.
  4. Medical Visualization: In the field of medicine, visualizing complex anatomical structures or surgical procedures in 3D holograms could aid in training and improve the understanding of medical professionals.

Challenges and Future Prospects:

While real-time 3D holograms on smartphones mark a significant leap forward, challenges such as the need for more powerful processors and enhanced display technologies still exist. Additionally, the development of holographic content creation tools and standards is crucial for widespread adoption.

Looking ahead, the integration of artificial intelligence and advancements in materials science may further refine and enhance the capabilities of real-time hologram technology. As the tech community continues to push the boundaries, we can anticipate a future where interactive and immersive holographic experiences become an integral part of our daily lives.

Recent Breakthroughs

In a groundbreaking development, researchers at Chiba University have introduced a cutting-edge deep-learning technique that simplifies the creation of holograms, enabling the generation of 3D images directly from standard 2D photos. The novel approach, relying on three deep neural networks, not only streamlines the hologram generation process but also surpasses the speed of current high-end graphics processing units. Unlike traditional holography, this method eliminates the need for costly equipment like RGB-D cameras after the training phase, making it cost-effective and offering applications in high-fidelity 3D displays and in-vehicle holographic systems.

3D Holographic Display Achieves Wide Viewing Angle, Large Images, reported in July 2022

A Beihang University research team created a holographic 3D display system that widens its viewing angle and enlarges image size through the simultaneous implementation of two different hologram generation methods. The system features a tunable liquid crystal grating with an adjustable period to widen the viewing angle. It provides a secondary diffraction of the reconstructed image to increase the image size.

The holographic 3D display system is composed of a laser, a beam expander, a beamsplitter, a spatial light modulator (SLM), a 4f system with two lenses, a filter, a polarized light valve, and a signal controller, in addition to the tunable liquid crystal grating. The response time of the grating is 29.2 ms, which meets the requirements for synchronous control.

To achieve a wide viewing angle, the researchers apply voltage to the liquid crystal grating, causing the liquid crystal molecules to assume a periodic order and the diffraction image to undergo a secondary diffraction.

Physicists create Star Trek-style holograms

Researchers at Bilkent University, Turkey, have achieved a significant advancement in holography, as highlighted in Nature Photonics. They developed a method to project holograms depicting complex 3D images by creating hundreds of image slices that could be used to re-synthesize the original scene. The breakthrough enables the simultaneous projection of fully 3D objects, including their back, middle, and front parts. By exploiting fundamental equations of light propagation invented by Fourier and Fresnel, the researchers eliminated interference issues using a corollary of the central limit theorem and the law of large numbers. The resulting holograms surpass previous digitally synthesized 3D holograms in quality metrics and find applications in 3D displays, medical visualization, air traffic control, laser-material interactions, and microscopy.

The researchers generated secondary diffraction images by tuning the liquid crystal grating’s period, adjusting the polarized light valve for uniform intensity. They created subholograms for a 3D object, adjusting the SLM and liquid crystal grating to generate primary and secondary maximums. The holographic 3D display system demonstrated a remarkable viewing angle of 57.4 inches, seven times that of conventional systems using a single SLM. The system magnified image size by 4.2 times and addressed discomfort issues associated with traditional 3D viewing systems. The researchers anticipate broad applicability in augmented reality displays, medical diagnostics, advertising, entertainment, and education. The study was published in Light: Science & Applications (DOI: 10.1038/s41377-022-00880-y).

High-Fidelity Mobile Hologram

With the unprecedented rate of advances in high-resolution rendering, wearable displays, and wireless networks, mobile devices will be able to render media for 3D hologram displays. Hologram is a next-generation media technology that can present gestures and facial expressions by means of a holographic display. The content to display can be obtained by means of real-time capture, transmission, and 3D rendering techniques. In order to provide hologram display as a part of real-time services, extremely high data rate transmission, hundreds of times greater than current 5G system, will be essential.

For example, 19.1 Gigapixel requires 1 terabits per second (Tbps) . A hologram display over a mobile device (one micro meter pixel size on a 6.7 inch display, i.e., 11.1 Gigapixel) form-factor requires at least 0.58 Tbps. Moreover, support of a human-sized hologram requires a significantly large number of pixels (e.g., requiring several Tbps) . The peak data rate of 5G is 20 Gbps. 5G cannot possibly support such an extremely large volume of data as required for hologram media in real-time. To reduce the magnitude of data communication required for hologram displays and realize it in the 6G era, AI can be leveraged to achieve efficient compression, extraction, and rendering of the hologram data. The market size for the hologram displays is expected to be $7.6 billion by year 2023.

VividQ, a UK-based deeptech startup, has developed cutting-edge technology capable of rendering holograms on existing screens, as reported in July 2021.

The company is directing its innovative Computer-Generated Holography towards applications in Automotive Head-Up Displays (HUD), head-mounted displays (HMDs), and smart glasses. This technology projects genuine 3D images with authentic depth of field, promising a more natural and immersive display experience for users.

Additionally, VividQ claims to have uncovered a method for transforming conventional LCD screens into holographic displays, expanding the potential applications of their technology. Darran Milne, co-founder and CEO of VividQ, envisions a future where holographic displays, once confined to the realm of science fiction in films like Iron Man and Star Trek, become a tangible reality. Milne expressed VividQ’s mission to introduce holographic displays to the world, anticipating transformative impacts on automotive displays, augmented reality experiences, and the way individuals interact with personal devices such as laptops and mobiles.

As technology continues to advance, the prospect of experiencing real-time 3D holograms on smartphones becomes increasingly tangible. The marriage of holographic displays with high-resolution rendering, wearable displays, and wireless networks opens avenues for immersive interactions. The challenges lie in overcoming data rate limitations for mobile devices, but leveraging artificial intelligence for efficient compression and rendering holds the key.

 

Conclusion:

The journey from static holograms to real-time 3D holograms on smartphones reflects a paradigm shift in visual technology. Holography, once confined to science fiction, is now poised to become an integral part of our everyday experiences. The marriage of deep learning, digital holography, and smartphone capabilities brings us closer to a future where holographic interactions seamlessly blend with our reality, offering a glimpse into a new era of visual innovation. The age of real-time 3D holograms is upon us, promising a tapestry of innovation and boundless possibilities.

 

 

References and Resources also include:

http://www.spie.org/news/hologram-reconstruction?

https://phys.org/news/2019-03-physicists-star-trek-style-holograms.html

https://interestingengineering.com/10-best-real-world-applications-of-hologram-technology

https://spectrum.ieee.org/tech-talk/computing/software/realtime-hologram

https://www.photonics.com/Articles/3D_Holographic_Display_Achieves_Wide_Viewing/a68191

 

 

 

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