Metallized holograms

Here a method to prepare reflective metal holograms that does not require vacuum environment or masking is discussed. Despite the disadvantages inherent in many electroless deposition techniques, one particular approach will be described that produces high resolution reflective metal holograms. 

Krattiger B, Bruin GJM, Bruno AE. Hologram-based refractive-index detector for capillary electrophoresis—Separation of metal-ions. Analytical Chemistry 66, 1-8, 1994. 

Bob looks at Mr. Plex to see what he is fiddling with at the bar. Mr. Plex is looking at a hologram of a girl Bob used to visit at art shows held in Martian caverns. The woman had a shaved area at the back of her head, in which a metal socket was surgically implanted. Mr. Plex must have picked up the hologram and looked at it at least a thousand times since Bob got it. Plex always put it back in the wrong place, when he was finished. You could tell he did it on purpose. 

The resulting relief-patterned metal surface serves to reflect incident light into a reconstructed image of the hologram. A disadvantage of this approach is the requirement to conduct such metal deposition in a vacuum environment and to mask areas where metal deposition is not desired, especially if the hologram is mounted on a document. 

A process to make and metallize a hologram will be described. Other optically variable devices or microimages will not be mentioned further in order to simplify the discussion. However, these images can be metallized similarly. 

A holographic polymeric substrate Is formed by casting and curing a polymer precursor in contact with a holographic relief-patterned mold to form a polymeric substrate with a holographic relief-patterned surface. Once cured, the web containing the hologram can be stored or run Into a second print station which applies the catalyst for electroless metal deposition. 

There was not an opportunity to run a continuous web of hologram material on a print station so that all the steps in the process were tested in sequence. A limited number of methods could be used to plate metals In a printing operation. A method of choice is a viscous plating solution. This could be applied over the catalyzed hologram using a gravure press. It would then be heated to accelerate metal deposition and then washed free of the spent plating solution. 

Fig. 11. Through TPF-based blow molding Blow molding with bulk metallic glasses (BMGs) permits hollow, thin, seamless shapes, which can include xmdercuts. These shapes were previously unachievable with any other metal processing method (A-C). The surface can be patterned, e.g., to reveal a hologram (D), joints can be created such as threads (F,H), and a second material can be joined to the BMG (E) in the same processing step than the blow molding. Reprinted from (Schroers, 2010), with permission from John Wdey and Sons.

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