| 摘要 |
1280996 Holography RCA CORPORATION 10 Sept 1969 [20 June 1968 (3)] 29579/68 29580/68 and 29581/68 Heading H4D [Also in Division G2] Holograms are produced by interfering a first coherent wave energy component, encoded with object information, with a second coherent wave energy component which has been acted on by a co-ordinated wave modifying structure (defined), the hologram being such that an image reconstructed therefrom will be modified by said structure. In one embodiment a laser beam 10 (Fig. 5) is split into two beams one of which 12, 84 is collimated and is encoded with information about object 26. Preferably the beam passes a diffuser 24 before the object. The other beam 14 is collimated and passed through a two-dimensional lens array 52 having a common focal plane C-C; the array produces a plurality of divergent reference beams. In effect the array forms a plurality of offset reference beams emanating as if from a plurality of spaced point sources. When the hologram is read-out with a beam equivalent to the original object-beam, but minus the object, a plurality of images are formed in the equivalent of plane C-C (Fig. 6, not shown). In an alternative embodiment the lens array is replaced by a pin hole plate. In a further embodiment (Fig. 10) an annular hologram 200 is formed. A laser beam 212 is reflected by mirrors 220, 214 located on the optic axis O-O of a parabolic mirror 226 and a lens-array 216. Light from mirror 220 passes a diffuser and object 224 located in focal plane of mirror 226 and is then reflected from mirror 226 as a parallel beam 228. Only an annular portion 232 falls on hologram plate 200. Light from mirror 214 passes through the lens array 216 and forms a plurality of divergent beams. Reconstruction of the hologram 200 by a parallel annular light beam from a parabolic mirror gives rise to a plurality of images of the object. The wave energy need not be light. It can be microwaves or acoustic waves. In such latter ease the mirrors and lenses will be of acoustical type.
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