FABRICATION DE HOLOGRAMME BLANCHI

摘要

1339991 Holography XEROX CORP 18 Jan 1971 [21 Jan 1970] 2262/71 Addition to 1231938 Heading G2J Blazed holograms are formed by exposing a photo-hardenable layer 32 having a randomly varying surface to an object modulated beam 22 directed at one face of the layer and a mutually coherent reference beam 26 directed at the other face of the layer to set up standing wave interference patterns. The developed hologram may be coated with a reflective metal e.g. aluminium. In reconstruction, a reconstructing beam of same coherence and wavelength as the reference beam may be made or a white light or multiwavelength beam may be used. The reconstructed image will be that only set up by the wavelength corresponding to the reference beam, other wavelengths will be diffused. To give multiple image the layer 32 may be sequentially exposed to light of different wavelengths, either through masks to avoid overlap or by using as a layer a material selectively hardenable by light of different wavelengths. The base 30 of the hologram is preferably a ground glass having one surface 34 randomly varying. This is coated with a photo-hardenable material 32. This may be a coating comprising a slurry of finely ground transparent material mixed with photo-resist. Alternatively a photo-hardenable layer may be coated on transparent substrate, the layer then being exposed to a highly diffuse beam of ultraviolet light. When developed the layer has a highly diffusing surface. During exposure the photo-hardenable layer 32 may be coated with a transparent layer 37 of same refractive index as layer 32. This extra coated may also be applied to the developed blazed hologram.