Today, converting the 2-D data of conventional medical images into useful 3-D clinical information requires mentally integrating the data into a 3-D image. The transformation, however, is frequently difficult even for experienced radiologists. Even with the Magnetic Resonance Imaging (MRI) device, and its remarkably sophisticated imaging, the end product image is only a 2-D presentation of 3-D. The same can be said for all ultrasound imaging devices employed throughout hospitals and in clinical laboratories; they give the illusion of 3-D, using computed 2-D (flat) images.

The Naval Laser Display Laboratory at the Naval Command, Control and Ocean Surveillance Center NCCOSC, RDT&E Division, San Diego, California, has developed its second-generation 3-D device for displaying data, information and scenes in 3-D color in real time within a 3-D volume of the image space. The device incorporates a 36-inch-diameter, 18-inch-high double helix that spins at approximately 10 revolutions per second, thereby filling a cylindrical volume. Under computer control, a laser beam is directed to illuminate certain discrete volume points (voxels) on the helix needed to create a scene. The laser light scatters from the surface of the helix, so, to the observer, each voxel appears to emanate from specific points. Each point has x-y coordinates determined by the position of the laser beam and a z coordinate. This is determined by the height of the point on the helix at the moment it is illuminated. Any point within the cylindrical volume can be computer-addressed to appropriately synchronize the laser beam, the Acousto-Optic (AO) Radome Scanner, and the phase of the helix.

Using a novel Acousto-Optic (AO) Random Scanner, up to 40K laser-generated volume points per color (120K points per 3-colors), are projected on the reflective surface of a 36-inch-diameter rotating helix. (This is about 10 times more than the current state-of-the-art.) The higher resolution allows improved color images, updated in real time, for group viewing with the naked eye.

By employing the fully developed high-resolution images of the 3-D Volumetric Display reported here, all the soft tissues of the body can be monitored in 3-D color and in real time. These tissues include such major organs as the heart, lungs, and liver. Even the unborn baby can be observed in 3-D while in the birth canal. These medical applications are under development. Additionally, this 3-D device is a logical host for some of the 3-D virtual reality software.