Scalable Upconversion Medium for Static Volumetric Display

Abstract

Efficient up-conversion emitters are necessary to generate a full-color 3D display. Rare-earth, co-doped fluorides that efficiently convert near infrared diode laser emission to visible red, green, and blue light by sequential two photon absorption are necessary to accomplish this. An up-conversion medium for a 3D display, particularly the CSpace “static volumetric display,” can be fabricated by grinding rare earth-doped fluoride bulk crystals and then dispersing the resultant microcrystals within an index matched host. This in turn leads to a reduction in display cost, weight, and growing time, as well as facilitating display scalability. To demonstrate a scalable medium for the CSpace display, several rare earth-doped fluoride bulk crystals were ground into micro crystal powders and then dispersed in liquids of different refractive index, including 1.45, 1.456, 1.46, 1.464, 1.468, 1.47, 1.474, 1.476, 1.48, 1.484, and 1.49. Fluorescence strength and transmission measurements were taken. Different particle concentrations were tested and demonstrated as well, and the detailed experimental results are described. A real volumetric 3D image was constructed inside a prototype display medium of 40×40×10 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> using the CSpace display. A potential future solution is presented, and suggestions to improve the scalable medium are given.