THREE DIMENSIONAL PROJECTION SYSTEMS BASED ON SWITCHABLE HOLOGRAPHIC OPTICS

摘要

Switchable holographic optical elements (HOEs) (320) that can be turned on and off are used in systems and methods for projecting 3-D images, or for projecting 2-D tiled images with increased size and/or resolution. In one embodiment, the method projects monochrome 3-D images through the steps of (a) displaying, at an object plane (310), a 2-D image (306; 307; 308) that is a cross section of a 3-D image, (b) activating an HOE (302) to focus the 2-D image onto an appropriate image plane (331; 332; 333; 334), and (c) repeating steps (a)-(b) for different cross sections of the 3-D image. Each of the cross sections is focussed onto a different image plane, so that the resulting images appear in an "image volume" (330) as a 3-D image. Steps (a)-(c) are then rapidly repeated at a fast rate (such as 60 frames per second) to create a continuously displayed 3-D image (335). The 3-D image may be a static image or a moving image. In another embodiment, the method includes steps of sequentially displaying 2-D cross-sectional images, and, in synchronization, sequentially activating switchable HOEs that image the cross sections onto different image planes. Also described is a 3-D projection system that includes (a) a 2-D display configured to sequentially display a series of cross sections and (b) an HOE configured to focus the 2-D display onto a series of image planes at different distances from the 2-D display. The switchable HOEs are also used in an image projection system that projects an image composed of an array of "tiles".