Volumetric display is like ‘3D printer for light’

Technology News | January 29, 2018

By Rich Pell

LEDlighting Optoelectronics Materials & processes Displays & Interfaces

Called the Optical Trap Display, the free-space volumetric display is based on “photophoretic optical trapping,” which basically uses a laser to trap and illuminate a cellulose particle, and then – by steering the laser beam around – move the particle and create an image. The technique, say the researchers, produces full-color, aerial volumetric images with 10-micron image points by persistence of vision.

“We refer to this colloquially as the Princess Leia project,” says BYU electrical and computer engineering professor and holography expert Daniel Smalley. “Our group has a mission to take the 3D displays of science fiction and make them real. We have created a display that can do that.”

Referring to the famous projected image of Princess Leia in the original Star Wars’ film, Smalley notes that, contrary to popular belief, the image of Princess Leia is not a hologram, which scatters light only at a 2D surface. A 3D image that floats in the air and that can be viewed from every angle is actually a volumetric image, he says.

As described in a related paper, the display works by “first isolating a cellulose particle in a photophoretic trap created by spherical and astigmatic aberrations. The trap and particle are then scanned through a display volume while being illuminated with red, green and blue light. The result is a three-dimensional image in free space with a large color gamut, fine detail and low apparent speckle.”

“This display is like a 3D printer for light,” says Smalley. “You’re actually printing an object in space with these little particles.”

The Optical Trap Display, say the researchers, is the first such example of volumetric imagery to use optical trapping and color effectively. Further, it is capable of producing image geometries that are currently unobtainable with holographic and light-field technologies, such as long-throw projections, tall sandtables, and “wrap-around” displays.

So far, the researchers have 3D-light-printed several tiny images. Looking ahead, says Smalley, “We’re providing a method to make a volumetric image that can create the images we imagine we’ll have in the future.”

For more, see “A photophoretic-trap volumetric display.”