A CRT display called a scanning halftone plotter has been developed. This device can display continuous-tone pictures on a cathode ray tube and serves as the device for displaying pictorial data in digital information processing by a computer. A significant feature of this plotter is the ability to draw computer-generated holograms economically. A very simple and straightforward treatment of the theory of the computer-generated hologram is demonstrated. The simplicity in mathematical treatment is achieved mainly by use of the halftone plotter. A new algorithm for the calculation of the light propagation from object planes composing a three-dimensional object is described. Holograms consisting of nonexistent three-dimensional objects have been synthesized according to this algorithm. By use of this algorithm, the so-called hidden line problem can be solved automatically. A simple method for improving the reconstructed image quality is also described. A halftone object has been successfully reconstructed by this method. Some applications of computer-generated hologram are demonstrated.
Y. Ichioka, M. Izumi, and T. Suzuki, "Scanning Halftone Plotter and Computer-Generated Continuous-Tone Hologram," Appl. Opt. 10, 403-411 (1971)