Mr. Alexander Kreft Profile

Alexander Kreft

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Proceedings Article | 18 February 2009 Paper

SOLIDFELIX: a transportable 3D static volume display

Knut Langhans, Alexander Kreft, Henrik Tom Wörden

Proceedings Volume 7237, 72371W (2009) https://doi.org/10.1117/12.807165

KEYWORDS: 3D displays, Upconversion, Crystals, Glasses, Doping, Luminescence, Polymers, 3D volumetric displays, Ions, ZBLAN

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Flat 2D screens cannot display complex 3D structures without the usage of different slices of the 3D model. Volumetric displays like the "FELIX 3D-Displays" can solve the problem. They provide space-filling images and are characterized by "multi-viewer" and "all-round view" capabilities without requiring cumbersome goggles. In the past many scientists tried to develop similar 3D displays. Our paper includes an overview from 1912 up to today. During several years of investigations on swept volume displays within the "FELIX 3D-Projekt" we learned about some significant disadvantages of rotating screens, for example hidden zones. For this reason the FELIX-Team started investigations also in the area of static volume displays. Within three years of research on our 3D static volume display at a normal high school in Germany we were able to achieve considerable results despite minor funding resources within this non-commercial group. Core element of our setup is the display volume which consists of a cubic transparent material (crystal, glass, or polymers doped with special ions, mainly from the rare earth group or other fluorescent materials). We focused our investigations on one frequency, two step upconversion (OFTS-UC) and two frequency, two step upconversion (TFTSUC) with IR-Lasers as excitation source. Our main interest was both to find an appropriate material and an appropriate doping for the display volume. Early experiments were carried out with CaF2 and YLiF4 crystals doped with 0.5 mol% Er3+-ions which were excited in order to create a volumetric pixel (voxel). In addition to that the crystals are limited to a very small size which is the reason why we later investigated on heavy metal fluoride glasses which are easier to produce in large sizes. Currently we are using a ZBLAN glass belonging to the mentioned group and making it possible to increase both the display volume and the brightness of the images significantly. Although, our display is currently monochrome, it is possible to create an RGB-display. For the same reasons we started tests with polymers. We were able to achieve meaningful results which point out a new direction in the investigation on polymers. For the reasons described above, our new solid state device is one of modular design. The simplicity to change all components makes it possible to do experiments with different display volumes and lasers for every specific purpose of the display in a very effective way. The images can be drawn inside the display volume by acousto-optic, galvanometric or polygon mirror deflection units. We control our galvanometric deflection unit with a personal computer and a selfwritten software which makes it easier to handle the setup and makes interactivity possible. This setup makes it a powerful and flexible tool to keep track with the rapid technological progress of today and helped us to experience the disadvantages and the advantages of most of the possible deflection units in practice. These experiences are a main element in our paper and lead to some conclusions which will be of big importance in future display developments. Potential applications include imaging and computer aided design as well as scientific data visualization.

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