We've seen a number of glasses-free 3D technologies in recent years, most famously in Nintendo's 3DS, but now researchers at the University of California at Berkeley and MIT have created a prototype device that allows those with vision problems to ditch their eyeglasses and contact lenses when viewing regular 2D computer displays by compensating for the viewer's visual impairment.
The prototype device consists of a screen printed with a matrix of pinholes measuring just 75 microns in diameter and separated by gaps 390 microns wide. This printed pinhole screen was then inserted between two layers of clear acrylic and attached it to an iPod display. Using an algorithm that takes into account a person's eyeglasses prescription, the screen is able to compensate for an individual's specific visual impairment by adjusting the intensity and direction of the light emitted from each screen pixel.
In this way, by way of a technique called deconvolution – a process of reversing optical distortion similar to that used to correct images on the Hubble telescope’s distorted mirror – the light from the image that passes through the pinhole matrix will be perceived by the user as a sharp image.
In a trial to test this set up, the team used a camera whose lens was adjusted to emulate farsightedness in a human eye, and then displayed images to that camera. When the image-correcting matrix was placed between the screen and the observing camera, the image resolved into sharp focus.
"Our technique distorts the image such that, when the intended user looks at the screen, the image will appear sharp to that particular viewer,” said Brian Barsky, UC Berkeley professor of computer science and vision science who is leading the project. "But if someone else were to look at the image, it would look bad."
Currently, the device also requires that the viewer remain in a fixed position for the matrix to be effective. However, Fu-Chung Huang, who is lead author of the study, says that eye-tracking technology could be used in future to allow the displays to adapt to the position of the viewer's head. He says the team also hopes to add multi-way correction that would allow users with different visual problems to view sharp images on the same display.
In addition to common problems such as farsightedness, the team says the technology could one day also help those with more complex problems, known as high order aberrations, which eyeglasses and contact lenses are unable to correct.
"We now live in a world where displays are ubiquitous, and being able to interact with displays is taken for granted," said Barsky. "People with higher order aberrations often have irregularities in the shape of the cornea, and this irregular shape makes it very difficult to have a contact lens that will fit. In some cases, this can be a barrier to holding certain jobs because many workers need to look at a screen as part of their work. This research could transform their lives, and I am passionate about that potential."
The research team's will present their findings at SIGGRAPH 2014 (Special Interest Group on Graphics and Interactive Techniques) conference in Vancouver, Canada on August 12th this year. Their paper is published in the journal ACM Transactions on Graphics.
The following video shows the prototype screen in use, and explains some of the background to its development.
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