Holographic 3D imaging of remote and close objects, and HOEs for it

Two types of holographic 3D imaging systems are considered. The first one is based on a so-called selectrogram, i.e., the structure that can be registered by using the light scattered by the object as a reference one. The distance to the object is not limited in this case because it does not effect the capability of the light scattered by the object to interfere with itself. Two methods that permit us to increase the diffraction efficiency of the selectogram are discussed and investigated. The first one involves the focusing of the image of the object in the region located near the surface of the selectogram. Special convenience of this method is that it is also accompanied by the increase of the candlepower of the optical system at the stage of the selectrogram recording. The second method to enhance the diffraction efficiency of the selectrogram involves the increase of the real physical depth of the recording by increasing the inclination of the rays that intersect the holographic layer. The Dupont photopolymer films that were sealed between two glass prisms with the help of immersion were used for the recording in this case. As a result of simultaneous applications of these methods, the brightness of the image reconstructed by the selectrogram became comparable with that of the image reconstructed by the hologram. The second type of a 3D imaging system being considered is designed for the recording of 3D holographic copies of small valuable objects. The parameters of this system are strongly influenced by the phenomenon of the shrinkage of the light-sensitive layer of the photographic plate. This phenomenon was eliminated by using photopolymer light- sensitive layers for the hologram recording.