A Varifocal Mirror Display Integrated Iwo A High-Speed Image Processor

A raster based variable focal length (varifocal) mirror display system, which is integrated into a high-speed 200 million instructions per second (MIPS) image processor (IP), is described. The display system is comprised of a loudspeaker-membrane-mirror subassembly, a suitable cathode ray tube (CRT) display monitor, and a display controller. The display controller is a single circuit board installed directly into the chassis of the IP. The stack of tomographic images, to be displayed as a three-dimensional raster, is stored in the 32 megabyte IP memory. Both the display controller and the computing engine of the IP have direct access to the image arrays over very high speed data pathways. The varifocal mirror display system uses a vibrating mirror in the form of an aluminized membrane stretched over a loudspeaker, coupled with a CRT suspended face down over the mirror. The mirror is made to vibrate back and forth, as a spherical cap, by exciting the loudspeaker with a 30 Hertz sine wave. Stacks of 2-D tomographic images are displayed, one image at a time, on the CRT in synchrony with the mirror motion. Because of the changing focal length of the mirror and the integrating nature of the human eye-brain combination, the time sequence of 2-D images, displayed on the CRT face, appears as a 3-D image in the mirror. The system simplifies procedures such as: reviewing large amounts of 3-D image information, exploring volume images in three dimensions, and gaining an appreciation or understanding of three-dimensional shapes and spatial relationships.