Color-encoded focused image holograms.

Color-encoded focused image holograms can be reconstructed in a white light projection system to form high fidelity color images. Use of frequency encoding leads to a simple, inexpensive optical reader similar to a conventional microfiche reader. The holograms can be formed as surface-relief, phase holograms in transparent media and can be replicated by embossing into thermoplastic film. Applications include micropublishing and related fields, where they offer a considerable cost advantage over conventional color microfiche. The characteristics of color reproduction are discussed; and the hologram recording, replication, and readout are described. An optimized set of parameters is derived, which gives colorimetry comparable with that of color television and a measured screen luminous emittance of 190 lx using a standard 150-W projection lamp and x15 magnification.