Hybrid reflection hologram

Abstract

Hybrid white-light viewable holograms and methods for making them. The holograms are hybrid reflection holograms made using the diffractive structures or gratings of a holographic object such as a transmission hologram or holographic optical element (HOE). The wavefronts of the diffractive structures are converted into a reflection hologram by scanning them with a coherent light source having a profiled narrow beam. The hybrid reflection hologram can exhibit display parameters including the multiple colors, solidity, and color stability of white light reflection holograms, the diffractive color shifting of a white light transmission hologram, three dimensional imaging and a wide variety of dynamic changes. Different areas or images with each of these effects can be combined in a single hologram. These hybrid reflection holograms are ideal for security and forgery prevention applications.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of the filing of U.S. Provisional Patent Application Ser. No. 60 / 783,502, entitled “Method and Apparatus for Mass Production of Volume Holograms from Plane Holograms”, filed on Mar. 17, 2006. This application is also a continuation-in-part application of U.S. patent application Ser. No. 11 / 459,821, entitled “Method and Apparatus for Mass Production of Holograms”, filed on Jul. 25, 2006, which application claims the benefit of the filing of U.S. Provisional Patent Application Ser. No. 60 / 702,785, entitled “Method and Apparatus for Mass Production of Reflection Holograms and Volume Holographic Optical Elements”, filed on Jul. 26, 2005. The specifications and claims of these patent applications are incorporated herein by reference.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention (Technical Field) [0003] The present invention is a method and apparatus for making a reflection hologram (or volum...

AI Technical Summary

Benefits of technology

[0019] An advantage of the present invention is that the diffraction color spectrum of a transmission hologram, such as a ‘Benton’ limited aperture white light transmission hologram, can be converted into a white light reflection hologram using either a single wave length laser (or other coherent light source) or tunable wavelength laser (or multiple single wavelength lasers) without the limitations of lack of color selection of objects typically involved in normal white light transmission holograms, and with an aperture that may be opened to any desired value.

[0020] Another advantage of the present invention is that multiple colors are achievable without using a mutable laser or without having to swell the emulsion between exposures.

Problems solved by technology

Any ambient light may alternatively be used, but this will typically produce lesser quality of the playback image.

It is a little more difficult to view a real image because the viewer must find the image and focus his or her eyes in front of the hologram; the hologram itself is typically less capable to act as a guide for the viewer's eyes.

The object holographed should be quite a bit smaller than the size of the film you are using, or the viewer will not be able to see the complete real image of the object all at once.

Also, without special precautions taken when constructing the hologram, the real image will be pseudoscopic.

However, although the master hologram is reproduced using an open aperture, the image is achromatic (black and white), and this method can only produce extremely shallow holograms without substantial blurriness.

However, Benton holograms may only be viewed from a small angular range due to the limited aperture; the entire hologram cannot be viewed from, for example, above or below.

Because a Benton hologram is a transmission hologram, color control is limited.

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