Rewritable Polymer

[MrPat]

Hi,

Is anyone using rewritable polymer material such as Nitto Denko's http://www.ndtcorp.com/?cmd=rd_02_opt_3? I am looking to start a project with it. I am also interested in finding any holographers close to Pittsburgh PA. (No, I am not trying to reproduce the Univ. of Arizona's work that appeared in Nature magazine... but you gotta love it.)

Thanks for any leads.

Best Regards,

MrPat

[Dinesh]

I was a consultant for Nitto Denko developing holographic applications for their material. It needs a fairly large voltage source attached to it, somewhere in the 7 to 9kV. So, you need to be a bit careful with the stuff. That said, I doubt that Nitto Denko would let you play with the stuff, it's tightly wrapped in corporate patents etc. However, Psaltis in Caltech has been writing papers on the polymer since the 90's ( typically: http://www.dmphotonics.com/Femtosecond_ ... eckman.pdf )

The University of Arizona's stuff is a little exaggerated. They're making standard slit holograms much like the Multiplex system of old. They're recording slits relatively quickly because they're using a pulse laser for each slit. This enables them to make the 50 or so slits in a matter of minutes. The material is then refreshed with a decay time of seconds by removal of the voltage source. With the voltage gone, the photorefractive effect is gone and the molecules stray out of the fringe areas, but this diffusion out of the fringe areas takes a little while. However, once the molecules have diffused into a non-coherent state, re-applying the field and imposing a new set of fringes causes the molecules to diffuse into the fringe areas, thus creating an index profile and a new set of slits is recorded. Thus you can "refresh" the images at a rate of several minutes. It's a lo-o-o-ng way from Princess Leia or update-able holographic TV! (Do you really want a 7kV source and a pulse laser - which of course you just happen to have lying around - every time you switched on the telly?)

[PinkysBrain]

That said, I doubt that Nitto Denko would let you play with the stuff, it's tightly wrapped in corporate patents etc.

What do the patents have to do with it? Wouldn't they be more likely to let people play with it the more securely patented it is?

PS. what is it being used for commercially any way? (Protecting high margins seems a much more likely reason to not give it to small fry.)

[Dinesh]

Wouldn't they be more likely to let people play with it the more securely patented it is?

The problem is with the words "securely patented". The stuff is still being developed, so it's still not a finished work. Until the polymer is ready for release to the public (or the marketplace), ie while it's still being developed, they're probably keeping it's precise formulation under wraps, except insofar as what's on the patent. The development work necessary to commercialise it is itself still under development. In other words, it's an ongoing research endeavour. Psaltis' papers have a basic formulation, but this formulation is slow to degenerate when the voltage is removed, and slow to record because the diffusion rate is not optimised. NDT have developed new ways to speed up both recording and erasure - I'm afraid I can't say how. However, some bright spark may find a way of doing an even better job of overcoming some basic scientific problems.

what is it being used for commercially any way?

It's not, to the best of my knowledge. Nitto does the basic scientific R&D, Nasser's group uses it to develop "holographic TV", among other things. I don't think it'll ever hit the streets as a holographic material. This is an expensive, high level optical, chemical engineering process and it's not designed for holographers like you and me! Unless you're a multi-national or mega-buck company/corporation which unfortunately we're not (yet!)

However, if you really wanted to play with it, there's enough in the Psaltis papers to make the stuff yourselves, providing you had the chemical facility. I haven't read the Psaltis papers in a couple of years, but I believe he gives the basic chemical make-up, not any algorithm for producing it.

[MrPat]

Is the ND stuff at all related to the old Digilens stuff? I lost track of them after they went under, but they were bought out by some entity IIRC.

---Still looking for holographers local to Pittsburgh.----

[Dinesh]

No, no relation to the digilens stuff, as far as I know. I don't know the digilens stuff, but I believe it's a liquid crystal, which the ND stuff is not. The ND stuff is a polymer