
Images:
Figure 1a) A fabricated DDHOE lens array; 1b) The 3-D display system consisting of a 2-D projector and DDHOE; 1c) A computer-modeled 3-D scene of depth 6 cm; 1d) A 3-D reconstruction of a modeled scene captured by camera looking into the DDHOE. Credit: Boaz Jessie Jackin.
New approach would eliminate visual disturbances without additional bulky optics
While most interaction with digital content is still constrained to keyboards and 2-D touch panels, augmented and virtually reality (AR/VR) technologies promise ever more freedom from these limitations.
AR/VR devices can have their own drawbacks, such as a tendency to induce visual motion sickness or other visual disturbances with prolonged usage due to their stereoscopy or auto-stereoscopy based designs. One promising solution is to adapt holography or light field technology into the devices instead. This, however, requires additional optics that would increase the size, weight, and cost of these devices — challenges that have so far prevented these devices from achieving commercial success.
Now, a group of researchers in Japan and Belgium has begun to explore a combination of holography and light field technologies as a way to reduce the size and cost of more people-friendly AR/VR devices. They will present their work during The Optical Society’s (OSA) Frontiers in Optics meeting, 16–20 September, in Washington, D.C. One of the themes of the meeting is virtual reality and augmented vision, with both a visionary speaker and a series of invited talks on those subjects.
“Objects we see around us scatter light in different directions at different intensities in a way defined by the object’s characteristic features—including size, thickness, distance, color, texture,” said researcher Boaz Jessie Jackin of the National Institute of Information and Communication Technology in Japan. “The modulated [scattered] light is then received by the human eye and its characteristic features are reconstructed within the human brain.”
Devices capable of generating the same modulated light—without the physical object present—are known as true 3-D displays, which includes holography and light-field displays. “Faithfully reproducing all of the object’s features, the so-called ‘modulation,’ is very expensive,” said Jackin. “The required modulation is first numerically computed and then converted into light signals by a liquid crystal device (LCD). These light signals are then picked up by other optical components like lenses, mirrors, beam combiners and so on.”
The additional optical components, which are usually made of glass, play an important role because they determine the final performance and size of the display device.
This is where holographic optical elements can make a big difference. “A holographic optical element is a thin sheet of photosensitive material—think photographic film—that can replicate the functions of one or more additional optical components,” said Jackin. “They aren’t bulky or heavy, and can be adapted into smaller form factors. Fabricating them emerged as a new challenge for us here, but we’ve developed a solution.”
Recording, or fabricating, a hologram that can replicate the function of a glass-made optical component requires that particular optical component to be physically present during the recording process. This recording is an analogue process that relies on lasers and recording film; no digital signals or information are used.
“Recording multiple optical components requires that all of them be present in the recording process, which makes it complex and, in most cases, impossible to do,” said Jackin.
The group decided to print/record the hologram digitally, calling the solution a “digitally designed holographic optical element” (DDHOE). They use a holographic recording process that requires none of the optical components to be physically present during the recording, yet all the optical components’ functions can be recorded.
“The idea is to digitally compute the hologram of all the optical functions [to be recorded and] reconstruct them together optically using a LCD and laser,” said Jackin. “This reconstructed optical signal resembles the light that is otherwise modulated by all of those optical components together. The reconstructed light is then used to record the final holographic optical element. Since the reconstructed light had all optical functions, the recorded hologram on the photosensitive film will be able to modulate a light with all of those functions. So all of the additional optics needed can be replaced by a single holographic film.”
In terms of applications, the researchers have already put DDHOE to the test on a head-up light field 3-D display. The system is see-through, so it’s suitable for augmented reality applications.
“Our system uses a commercially available 2-D projector to display a set of multi-view images onto a micro-lens array sheet—which is usually glass or plastic,” said Jackin. “The sheet receives the light from the projector and modulates it to reconstruct the 3-D images in space, so a viewer looking through the micro-lens array perceives the image in 3-D.”
One big difficulty their approach overcomes is that light from a 2-D projector diverges and must be made collimated into a parallel beam before it hits the micro-lens array in order to accurately reconstruct the 3-D images in space.
“As displays get larger, the collimating lens should also increase in size. This leads to a bulky and heavy lens, the system consuming long optical path length and also the fabrication of the collimating lens gets costly,” said Jackin. “It’s the main bottleneck preventing such a system from achieving any commercial success.”
Jackin and colleagues’ approach completely avoids the requirement of collimation optics by incorporating its function on the lens array itself. The micro-lens array is a fabricated DDHOE, which includes the collimating functions.
The researchers went on to create a head-up, see-through 3-D display, which could soon offer an alternative to the current models that use the bulky collimation optics.
Learn more: Holography, Light-Field Technology Combo Could Deliver Practical 3-D Displays
The Latest on: AR/VR devices
via Google News
The Latest on: AR/VR devices
- Apple VR headset – Ongoing developments and things to knowon January 24, 2021 at 3:02 am
Apple has been chasing after augmented reality and virtual reality for almost a decade now, hoping to come up with a commercially feasible product that changes the way we interact with our devices ...
- Apple glasses, AR/VR headsets: These are the latest leaks and rumorson January 22, 2021 at 9:19 am
Apple's next big product looks to be a VR headset. Or smartglasses. Or both. Here's what to expect, and our guesses as to what else might happen.
- Apple VR, AR glasses leaks and rumors: What we expecton January 22, 2021 at 4:04 am
Apple's next big product looks to be a VR headset. Or smartglasses. Or both. Here's what to expect, and our guesses as to what else might happen.
- Apple reportedly working on VR headset as part of augmented reality ambitionson January 22, 2021 at 3:41 am
Tech giant Apple is reportedly developing a virtual reality headset, leading toward the potential release of augmented reality glasses for consumers.
- Apple’s AR and VR Devices: The Next Big Thing?on January 21, 2021 at 12:32 pm
The rumor mill is churning once again, with Apple’s new VR and AR devices speculated to hit the market in the next few years. Will they be the Cupertino company’s next big thing?
- Expensive Apple VR headset tipped, as AR device hits technical skidson January 21, 2021 at 11:21 am
Apple may bring a standalone virtual reality headset to market before the arrival of the long-mooted AR glasses | Trusted Reviews ...
- Apple VR headset in the works, AR glasses coming lateron January 21, 2021 at 9:13 am
Apple has a virtual reality headset in the works with premium features and a high price tag, according to a report. It is expected to launch as soon as 2022.
- Apple’s VR headset could be an appetizer for AR glasses – here’s when it might launchon January 21, 2021 at 9:06 am
Apple’s first VR headset could make its long-awaited debut as early as 2022. Bloomberg reports that Apple is working on a niche, expensive VR headset that would serve as a precursor to more ...
- Apple’s first headset will be the Mac Pro of VR devices – Bloombergon January 21, 2021 at 5:21 am
A new Bloomberg report suggests that Apple's first headset will primarily be a VR device, with limited AR capabilities. It goes on ...
via Bing News