Embossing holograms in steel using explosives

DrOutlier · Post by **DrOutlier** » Fri Mar 07, 2008 10:53 am

Researchers at the Fraunhofer Institute for Chemical Technology ICT in Pfinztal are using explosives to impress holograms in steel.

http://www.physorg.com/news124039000.html

Tom B. · Post by **Tom B.** » Sat Mar 08, 2008 2:36 am

I wonder if this might be using a shaped charge effect where fringes on a relatively soft template (say a copper or nickel
surface relief hologram) focus the blast energy to deform the much harder underlying steel. Pretty neat if this works...

Colin Kaminski · Post by **Colin Kaminski** » Sat Mar 08, 2008 3:23 am

I think they are simply etching the steel to a patern then using the explosives to imprint a softer material. See the post in general holography as well.

Tom B. · Post by **Tom B.** » Sat Mar 08, 2008 8:09 am

I suppose etching at this scale might be possible, after all ICs are down to 45 nm or less, but it hardly seems efficient to
use explosives to transfer holopatterns from steel to plastic when simple pressure has worked OK with softer nickel shims
in the past.

Unfortunately, my Google searches only turn up dozens of blogified regurgitations of the same Fraunhofer press release which
does not offer much detail. Maybe now that their MP3 patent is near expiration they feel obliged to cast about for new sources
of funding...

DrOutlier · Post by **DrOutlier** » Sat Mar 08, 2008 11:26 am

Tom B. wrote:I wonder if this might be using a shaped charge effect where fringes on a relatively soft template (say a copper or nickel
surface relief hologram) focus the blast energy to deform the much harder underlying steel. Pretty neat if this works...

The article mentions that the researchers used sheet explosives. From my very limited knowledge and a quick Google search (in case Homeland was wondering; that's why I went to those sites) sheet explosives have a high detonation velocity and confining the force focuses it on a much smaller area and the pressure is massively intensified.

This is limited knowledge so any expert correction is welcomed.

Joe Farina · Post by **Joe Farina** » Sat Mar 08, 2008 11:50 am

I would think that any shim would have to be harder than the material that is embossed. So I wonder how the grating gets into a very hard material in the first place. Diffraction gratings can be chemically etched, but of course a light-sensitive material is needed in the first place, like photoresist. At first glance, the process seems impractical, but who knows. Not enough information is given.

Martin · Post by **Martin** » Sat Mar 08, 2008 12:51 pm

Here's a bit more information – though in German only: http://www.holo-impact.de/

Tom B. · Post by **Tom B.** » Sun Mar 09, 2008 2:04 am

The phrase I was thinking of was "explosively formed penetrator" as described here: http://en.wikipedia.org/wiki/Explosivel ... penetrator

The thought being that the hills and valleys of fringes in a soft metal shim could, when zapped with an explosive shock wave maybe concentrate the energy enough to penetrate some small distance into a steel surface.