Jor enter a virtual environment, users must don a set of VR glasses (see photo). Typically, these contain a pair of stereoscopic lenses and a light-emitting diode (DIRECTED) display screen. The lenses distort the image on the screen so that it appears to be three-dimensional. And various sensors in the glasses track the position of the user’s head, to coordinate it with what’s being viewed.
A group of researchers based at the Massachusetts Institute of Technology (MIT), together with colleagues from universities in France, South Korea and other parts of America, found a way to organize DIRECTED pixels to produce screens with much higher resolution than is currently possible. As they report this week in Naturetheir technique could be used to make VR images that look much more realistic than those of today. “You could have a completely immersive experience and couldn’t tell the virtual from the real,” says Jiho Shin, one of the team members.
To generate displays with increasingly higher resolution, DIRECTED the pixels got smaller and smaller. But that makes them increasingly difficult to manufacture reliably. Some in the industry believe that a practical limit will soon be reached. Still, the smaller pixels are especially useful for enhancing screens that are viewed up close, such as with a VR helmet. Insufficient pixel density can lead to unwanted optical illusions, such as perceived banding in the image.
Now, DIRECTEDs are fabricated like silicon chips. The red, green and blue versions needed for a full range of colors are grown on different slices, then cut and placed side by side, with microscopic precision, to form pixels. Misalignment leads to rejection. And more the DIRECTED, the greater the risk of misalignment. Today DIRECTEDs can be quite small (less than 100 microns in diameter). But eyewear makers would prefer something much smaller than that.
Dr Shin and his colleagues think they may turn out so tiny DIRECTEDs approaching things differently. They grow their diodes directly on reusable wafers of silicon and other materials to produce a single crystal membrane. These membranes can then be peeled off, stacked on top of each other like layers of a cake and cut into patterns of tiny vertical pixels, each as small as four microns in diameter.
As with the classic side-by-side DIRECTEDs, the team verticals give a full spectrum. The result must be perfect for VR protective glasses. And goggle shields could be just the start. Now that TVs come in curved and foldable forms, they can also be used to surround a viewer in a virtual environment. Someday, maybe, stacked mic DIRECTEDs could even bring the immersive experience to the big screen of the cinema itself.