Free-space volumetric displays, or displays that create luminous image points in space, are the technology that most closely resembles the three-dimensional displays of popular fiction1. Such displays are capable of producing images in ‘thin air’ that are visible from almost any direction and are not subject to clipping. Clipping restricts the utility of all three-dimensional displays that modulate light at a two-dimensional surface with an edge boundary; these include holographic displays, nanophotonic arrays, plasmonic displays, lenticular or lenslet displays and all technologies in which the light scattering surface and the image point are physically separate. Here we present a free-space volumetric display based on photophoretic optical trapping2 that produces full-colour graphics in free space with ten-micrometre image points using persistence of vision. This 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 colour gamut, fine detail and low apparent speckle. This platform, named the Optical Trap Display, 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’ displays1.
We thank L. Baxter from Brigham Young University, Chemical Engineering Department, for use of his equipment, as well as G. Nielson, V. M. Bove Jr and P.-A. Blanche for discussions. We are grateful to S. Hilton for help with 3D printing. We acknowledge the Blender Foundation for content (Fig. 3c; adapted from http://www.bigbuckbunny.org under a Creative Commons license, https://creativecommons.org/licenses/by/3.0/) and software for 3D image conversion. We also acknowledge those who supplied source material for the holograms and volumetric images shown. B. Wilcox and Brigham Young University Communications provided footage of the Y logo in Fig. 1 and Supplementary Video 1. The butterfly image used to create the volumetric image and holograms shown in Fig. 2a and Extended Data Fig. 1a, b was sourced from Rvector, Shutterstock. The volumetric image in Fig. 3d was generated from NASA photograph number AC75-0027. The image of the arm shown in Fig. 2h and illustrated in Extended Data Fig. 1e was created using a model from clayguy, CGTrader. The model of the sitting human figure that is 3D-printed in Fig. 2g and illustrated in Extended Data Fig. 1d was sourced from fletch55, 3D Warehouse.
Extended data figures
This video shows a photophoretic image of the Brigham Young University, ‘Y’ logo drawn at persistence of vision rates (>10 Hz) in freespace. The illumination color of the logo is slowly varied.
In this video high-acceleration movements, jumps, rasters, and random walks are shown.