Promise of Holographic Displays

 ACM NEWS

Talked these in terms of advertising

The Promise of Holographic Displays

By Sandrine Ceurstemont

Commissioned by CACM Staff, June 1, 2023

Unlike today's two-dimensional computer screens, holographic displays could soon present images that appear to be in three dimensions.

The next generation of computer screens could incorporate holographic displays, allowing us to interact with images and videos that appear to be presented in three dimensions.

Instead of interacting with real-time videos of colleagues during videoconferences, they could be represented as holograms. Medical professionals could be presented with three-dimensional (3D) views of organs and scans to help diagnose conditions and plan surgeries. Holographic representations are also of interest for defense applications, to better visualize a battlefield when preparing missions.

"The promise of holography is to project images that you can almost not distinguish from reality," says Theo Marescaux, founder and chief product officer of Swave Photonics, a fabless semiconductor company based in Leuven, Belgium.

Holography can be thought of as photography's 3D counterpart. Whereas a photo captures the varying intensity of light in a scene, a hologram also incorporates the light's phase—a light wave's position in its cycle at a point in time—which allows a 3D image to be recreated. In traditional holography, a light beam from a coherent light source such as a laser, which emits light waves of the same phase, is split in two to illuminate a scene. A hologram can then be produced by recording the interference pattern of the two beams. With computer-generated holography, algorithms can be used to simulate the process in order to create holographic displays.

Virtual reality (VR) is often considered to be a competing technology since it also aims to mimic the real world. VR headsets provide a stereoscopic view and typically track a user's head pose to make them feel immersed in a virtual scene. However, when creating the illusion of depth, virtual objects at certain distances often look blurry, since there can be a mismatch between their perceived location in space and the focusing distance, which is the screen from which they are being projected. The discrepancy can also make users feel nauseous after long-term use. In contrast, "With holography, you don't have that because you're reconstructing the entire image with perfect focus at any point in space," says Marescaux.

Furthermore, virtual reality generates a 3D view for a single user, whereas holographic displays could create virtual objects capable of being viewed by many people simultaneously. "You could have different perspectives represented in a big format display [so that] people can look at things from different angles," says Kaan Aksit, an associate professor at University College London in the U.K., who is researching 3D display technologies.

Challenges

There are challenges to overcome, however, before holographic displays can be made real. One is that generating holograms is computationally expensive, since all the light rays in a 3D scene, passing through every point of every object and in every direction, must be recorded and reconstructed, including all the depth cues perceived by the human eye. Supercomputers have been used to create accurate simulations of the underlying physics, but even so it can take minutes to produce a single holographic image.

To speed up the process, Liang Shi, a Ph.D. student in the Computer Science and Artificial Intelligence Laboratory (CSAIL) of the Massachusetts Institute of Technology (MIT), worked with colleagues to develop a deep learning method called tensor holography that can reduce the amount of computation required.

The researchers first created a dataset containing 4,000 images, with color and depth information for each pixel of each image, and a corresponding 3D hologram for each image. They then trained their deep learning model with the pairs of visuals, after which the system was able to uncover the underlying relationship between an image and its holographic counterpart.  ... ' 

Google Pushing Advanced Wearables

Good to see Google pushing this research. Still consider the use of this kind of focused wearable to have narrow uses, until people decide it to be part of their normal clothing.

Google is quietly experimenting with holographic glasses and smart tattoos
The search giant has been working on or funding a new generation of wearable technology.
Richard Nieva in CNET

A simple pair of sunglasses that projects holographic icons. A smartwatch that has a digital screen but analog hands. A temporary tattoo that, when applied to your skin, transforms your body into a living touchpad. A virtual reality controller that lets you pick up objects in digital worlds and feel their weight as you swing them around. Those are some of the projects Google has quietly been developing or funding, according to white papers and demo videos, in an effort to create the next generation of wearable technology devices.

The eyewear and smartwatch projects come from the search giant's Interaction Lab, an initiative aimed at intertwining digital and physical experiences. It's part of Google Research, an arm of the search giant with roots in academia that focuses on technical breakthroughs. The Interaction Lab was created within Google's hardware division in 2015, before it was spun out to join the company's research arm about two years ago, according to the resume of Alex Olwal, the lab's leader. Olwal, a senior Google researcher, previously worked at X, the company's self-described moonshot factory, and ATAP, Google's experimental hardware branch. 

The goal of the Interaction Lab is to expand Google's "capabilities for rapid hardware prototyping of wearable concepts and interface technology," Olwal writes. Its initiatives appear to be more science experiment than product roadmap, with the likely goal of proving ideas rather than competing with the Apple Watch or Snapchat Spectacles. But taken together, they provide a glimpse at Google's ambitions for wearable tech.

The other projects were collaborations with researchers from universities around the world. At least two of them -- the VR controller and smart tattoos -- were partly funded through Google Faculty Research Awards, which support academic work related to computer science and engineering. The efforts highlight Google's close ties with the academic community, a bridge to the company's beginnings as a Stanford University grad school project by co-founders Larry Page and Sergey Brin that grew into a global behemoth with deep hooks into our lives. .... "

Facebook Reveals Holographic Optics for Thin, Light VR Headsets

Technically interesting  next step via Facebook.  Still apparently in early stages. 

Facebook Reveals Holographic Optics for Thin, Light VR Headsets
VentureBeat
Jeremy Horwitz

Facebook has unveiled a holographic optical framework for thinner, lighter virtual reality (VR) headsets, which it expects to be incorporated within high-performance devices for VR and augmented reality. The "pancake optics" system combines thin layers of holographic film with a laser projection system and directional backlights, in order to project either flat imagery or volumetric holograms. The optical system can range from 11 millimeters to less than 9 millimeters thick, while each prototype eye display has a resolution of about 1,200 by 1,600 pixels, with a field of view that is either a 93-degree circle or a 92-by-69-degree rectangle. The researchers said the device is not ready for near-term deployment. .. " 

Advanced Holograms

In CWorld:   The advance mentioned below is important:

  ... Holograms have been part of the business and science community's toolset for some time but Microsoft is highlighting just how advanced they have become lately. .... 

Wide angle holograms
Rayvel, which specializes in advanced holographics, was recently awarded a patent for its wide angle hologram technology that enables the production of compact holographic displays.

This is how Rayvel explains the problem it takes on with its technology:

A hologram appears when it is illuminated from a light source at an angle that is determined during the manufacturing process. Typically it is a source at about a 45 degree angle from the hologram. It also usually needs to be placed at a distance from the hologram: the larger the hologram the further away the light source needs to be. This new invention allows the light source to be nearly parallel and close to the hologram, allowing the design of significantly flatter image display systems, useful for advertising signage, point-of-purchase, and trade shows. ....  "  

Holographs Brings Back Performers

In the CACM:  Technical, but very readable piece on the history and use of the holographic illusion. Remember seeing these live in Disney World a long time ago, their improvement has been considerable, bringing back the dead, and enhancing the living.  We saw holographic packaging displays demonstrated.  Some augmented reality ideas embed holographics.   Engagement, or a scary uncanny valley?  Holographic Projection Systems Provide Eternal Life?