No matter how many times 3D displays emerge and fade, the tech refuses to die. Researchers from Soochow University have now developed a glasses-free 3D display prototype, which uses a series of nanostructured lenses to produce more realistic images that can be seen over a longer viewing distance.
3D was the hot new movie trend of the 50s, 80s, and 2000s, but it fails to catch on every time. The need to wear special glasses not only puts many people off, but limits the potential applications of 3D displays and holograms. Glasses-free displays have long been in development and even seen commercial release, in the form of TVs, phones, laptops or most famously the Nintendo 3DS. But unfortunately they suffer their own tech issues, including narrow viewing angles or short viewing distances.
The researchers on this new study have attempted to overcome these issues with a new light field 3D display. These systems project a dense field of light rays that create a three dimensional effect, which can be viewed by several people from different angles without needing glasses.
The key to the team’s design was a new flat lens, patterned with nanoscale structures that diffract light in certain ways. Combining several of these lenses, patterned in different ways, can create multiple views within the same light field, so people watching from different angles will see slightly different things – key to creating that 3D illusion. The design also helps the effect be seen from further away.
“Most light field 3D displays have a limited viewing range, which causes the 3D virtual image to degrade as the observer moves farther away from the device,” said Wen Qiao, lead researcher on the project. “The nanostructured flat lens we designed is just 100 microns thick and has a very large depth of focus, which enables a high-quality virtual 3D scene to be seen from farther away.”
The prototype system used a 4-in (10-cm) display, with a resolution of 568 x 320 pixels per eye. The team says that the device was able to produce 3D images that could be viewed between 9.4 and 35.4 in (24 and 90 cm) away, which is a greater distance than most light field displays.
Light efficiency reached 82 percent, which is important for creating bright images, and “crosstalk” – which is where images from each eye bleed into each other, distorting the 3D effect – was reduced to less than 26 percent.
The main downside to the prototype was the viewing angle, which was a mere nine degrees. That means viewers need to look at the display from straight on, and any slight movements to the side would ruin the 3D effect. However, the researchers say that the nanostructures on the lenses could be tweaked to boost that figure, potentially bumping it up to almost 180 degrees.
Investigating better ways to etch those nanostructures is the team’s priority for future work, which should also help improve the light efficiency.
The research was published in the journal Optica.
Source: Optica
