Variable focus skinny lens designed for increase

Experimental setup

picture: Researchers developed a really skinny lens with a repeatedly tunable focal size and confirmed that it may possibly assist overcome vergence-accommodation battle in an AR system.
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Credit score: Yan Li, Shanghai Jiao Tong College

WASHINGTON—Researchers have developed a skinny lens with a repeatedly tunable focal size. The brand new lens may someday make visible fatigue from augmented and digital actuality (AR/VR) gadgets a factor of the previous.

“Most of the 3D shows utilized in at present’s AR/VR gadgets trigger discomfort after long-term use because of the vergence-accommodation battle,” stated analysis staff chief Yan Li from Shanghai Jiao Tong College in China. “Our lens, which is called an Alvarez lens, can be utilized to alleviate this drawback. This might present a extra comfy and extra real looking 3D expertise that will allow extra widespread use of AR/VR headsets.” 

The researchers describe their new lens within the Optica Publishing Group journal Optics Categorical. It’s produced from two flat, or planar, liquid crystal components that may be moved in relation to one another to repeatedly change the lens’s focal size. To show the brand new Alvarez lens, they integrated it into an AR show system that displayed digital photographs on a real-world view at completely different depths.

“This lens has a steady and enormous tuning vary, a skinny formfactor, is light-weight and will be made utilizing a easy low-cost fabrication course of,” stated Li, who collaborated with Shin-Tson Wu’s lab on the College of Central Florida Faculty of Optics and Photonics. “Along with AR/VR gadgets, this kind of compact tunable lens could possibly be helpful for microscopic imaging, machine imaginative and prescient, laser processing and ophthalmology.”

Enhancing the digital expertise

In AR/VR gadgets, the vergence-accommodation battle happens as a result of the left and proper eyes obtain two barely completely different photographs that the mind places collectively to type a digital 3D picture. To see the picture clearly, every eye focuses on the mounted 2D aircraft the place the picture is displayed. This causes the merged 3D picture and the one eye focus on the 2D aircraft to be inconsistent, resulting in dizziness and visible fatigue.

It’s attainable to minimize the vergence-accommodation battle with a vari-focal show, which dynamically adjustments the depth of single-plane digital objects in order that digital objects seem to exist at completely different depths in several moments. An alternative choice is a multi-focal show system, which renders a number of 2D cross-sections of a digital object at a number of depths concurrently to reconstruct a 3D quantity. In each instances, the VAC drawback is suppressed as a result of the human eye can concentrate on the proper depths of the digital objects.

Vari- or multi-focal show techniques want a tunable lens that may change focus repeatedly inside a wide range whereas additionally being compact and light-weight sufficient to be helpful in head-mounted AR/VR gadgets. Li has been engaged on fatigue-free AR shows and liquid crystal gadgets for about 10 years and just lately developed a approach to fabricate a liquid crystal based mostly diffractive optical element generally known as a Pancharatnam-Berry (PB) optical ingredient that can be utilized to create a tunable lens that meets these necessities.

“Our technique permits Pancharatnam-Berry optical components with the difficult and irregular section profiles wanted to create an Alvarez lens with excessive precision, low value and unprecedented comfort,” stated Li. “We needed to see if this ultracompact Alvarez tunable lens may provide an answer to the long-standing vergence-accommodation battle drawback in VR and AR shows.”

AR show demonstration

The researchers used their new strategy to create a tunable Alvarez lens fabricated from two planar Pancharatnam-Berry liquid crystal components. In every ingredient, an ultrathin polymetric liquid crystal layer only a few hundred nanometers thick is coated onto a 1-mm-thick glass substrate. They integrated this Alvarez lens into an AR show system constructed utilizing off-the-shelf optical components on an optical desk. By laterally shifting the 2 components of the Alvarez lens, they had been in a position to repeatedly tune the depth of the digital picture from close to to far distances.

“Regardless of the depth, the digital picture exhibited the identical in-and-out of focus impact as the actual 3D objects in the actual world,” stated Li. “This meant that the human eye may at all times concentrate on the depth of the digital 3D picture appropriately, thus overcoming the vergence-accommodation battle drawback.”

The Alvarez lens demonstrated on this work was optimized for single-color operation at 532 nm, however the researchers are engaged on methods to make use of it for a full-color show. Additionally they wish to undertake an digital technique for controlling the lateral displacement between the optical components, which was carried out manually on this analysis.

Paper: S. Chen, J. Lin, Z. He, Y. Li, Y. Su, S.-T. Wu, “Planar Alvarez tunable lens based mostly on polymetric liquid crystal Pancharatnam-Berry optical components,” Decide. Categorical, 30, 19, 34655-34664 (2022).  

DOI: 10.1364/OE.468647.

About Optics Categorical

Optics Categorical experiences on scientific and know-how improvements in all points of optics and photonics. The bi-weekly journal supplies speedy publication of unique, peer-reviewed papers. It’s printed by Optica Publishing Group and led by Editor-in-Chief James Leger of the College of Minnesota, USA. Optics Categorical is an open-access journal and is on the market without charge to readers on-line.  For extra data, go to Optics Categorical.

About Optica Publishing Group (previously OSA)

Optica Publishing Group is a division of Optica (previously OSA), Advancing Optics and Photonics Worldwide. It publishes the most important assortment of peer-reviewed content material in optics and photonics, together with 18 prestigious journals, the society’s flagship member journal, and papers from greater than 835 conferences, together with 6,500+ related movies. With over 400,000 journal articles, convention papers and movies to look, uncover and entry, Optica Publishing Group represents the total vary of analysis within the area from across the globe.

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