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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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