Scientists at the University of Texas Southwestern Medical Center at Dallas have constructed a proof-of-concept system that projects true dynamic holographic images by computing the hologram of objects in a 3-D scene and then transcribing the 2-D digital hologram onto a digital micromirror system illuminated with coherent light. Besides the micromirror, the optical system used includes a 15-mW HeNe laser, a spatial filter, a collimating lens with a 10-cm focal length, a converging lens with a 40-cm focal length and an image reconstructor for real image viewing. The reconstructor, say the scientists, can be a frosted glass plate, fiber optic magnifier or CCD digital camera for visualization of a planar cross section of a 3-D image, or it may be a translucent block that allows creating a suspension of microscatter bodies to simultaneously view the whole 3-D real image.
   By removing the image reconstructor and convergent lens from the optical system and using neutral density filters to reduce laser intensity, it also is possible to observe the 3-D holographic virtual image by looking directly into the digital micromirror system. As reported in the March 10 edition of Optics Express, the scientists believe they have demonstrated that the micromirror device can function as a reflective holographic medium in either projection mode.