摘要: The two basic classes of volumetric displays are swept volume techniques and static volume techniques. During several years of investigations on swept volume displays within the FELIX 3D Project we learned about some significant d... 展开 The two basic classes of volumetric displays are swept volume techniques and static volume techniques. During several years of investigations on swept volume displays within the FELIX 3D Project we learned about some significant disadvantages of rotating screens, one of them being the presence of hidden zones, and therefore started investigations on static volume displays two years ago with a new group of high school students. Systems which are able to create a space-filling imagery without any moving parts are classified as static volume displays. A static setup e.g. a transparent crystal describes the complete volume of the display and is doped with optically active ions of rare earths. These ions are excited in two steps by two intersecting IR-laser beams with different wavelengths (two-frequency, two-step upconversion) and afterwards emit visible photons. Suitable host materials are crystals, various special glasses and in future even polymers. The advantage of this approach is that there are only very little hidden zones which leads to a larger field of view and a larger viewing zone, the main disadvantage is the small size of the currently used fluoride crystals. Recently we started working with yttrium-lithium-fluoride (YLiF_4) crystals, which are still very small but offer bright voxels with less laser-power than necessary in CaF_2 crystals. Potential applications are for example in medical imaging, entertainment and computer aided design. 收起