Anyone who has seen Star Wars envisions the future of visual displays as “holograms,” where 3D objects materialize out of light in thin air. However, anyone who has looked at a true hologram will likely have been disappointed at the reality. Not only does the image not pop out in its full glorious 3-dimensions in front of you, but the object is typically only visible from a narrow range of angles. Researchers at Brigham Young University (BYU) have developed a far more true-to-science-fiction display that is described as a “3D-printed light image.”
To circumvent the limitations of holograms, the BYU researchers describe in D.E. Smalley, et. al. a volumetric display that acts like a dynamic, light “etch-a-sketch.” They use a process called “photophoretic-trapping” by having a laser beam physically drag around an opaque particle. This particle is dragged through a secondary illumination that then scatters light and draws an image. The human eye can only see changes to an image at a rate of 10 frames per second, so by dragging the cellulose particle rapidly enough, the eye sees the line of the particle’s path instead of its instantaneous location. Since the particle is also reflecting light from the illumination field as it traces out the 3D object, it is visible at almost all angles around it.
While the current technology can only convincingly trace out a small 3D image a few centimeters in size, this is an impressive step in the direction of producing visual displays of 3D objects that take up physical space in front of you.