Real-time holographic display: Improvements using a multichannel acousto-optic modulator and holographic optical elements

Any practical holographic display device relying on the MIT synthetic aperture approach will require timebandwith products far exceeding those available with single channel acousto-optic modulators (AOMs). A solution to this problem is to use a multichannel AOM, thus making use of the parallelism inherent in optical systems. It is now technically feasible to accomodate a large number of acoustic channels on a single crystal with a corresponding improvement in image characteristics. The vertical view zone also becomes a significant problem for any large size display since each horizontal scan line line is visible only from a narrow angle in the vertical direction. Using holographic optical elements (HOEs) alleviates this limitation in two ways: First, the interline spacing can be adjusted easily with HOEs. Second, it is possible to manufacture an HOE which will act as a one-dimensional diffuser. Placing such an HOE in the vertical focus plane of the display increases the view zone by diffusing each line in the vertical direction, but leaves the horizontal image content unaltered.