ORWO spectral plates

holo_cyware · Post by **holo_cyware** » Thu Jul 16, 2009 9:38 am

I have the opportunity to get some spectral plates (they are used to make a shot of the spectral lines of a chemical excited in a spark).

These plates are supposedly very sensitive to any light frequency, as they have to cover the whole spectral width; besides the actual "spark" is extremly short and it could be faint too.

Does anyone has an idea of how can they be used? I'm planning to do more research as trying to shot a hologram, and in the worst case scenario to bleach them, so I can resensitize the nice gelatin layer.

BTW, what would be the best "washing" bath for an already exposed plate (to get the gelatin layer clean)?

Ed Wesly · Post by **Ed Wesly** » Fri Jul 17, 2009 1:15 pm

I went to the ORWO english site and couldn't find any mention of this product. Do you have a spec sheet on this material? It might be usable for holography, after all, and Eastman Kodak product, 649-F Spectroscopic plates were the mainstay of the industry at the beginning.

To remove everything from an emulsion, first convert all the silver to a silver halide by using a rehalogenating bleach, all sorts of formulae in the Forum's Wiki, then fix, using a photo fixer like the ones in camera stores, but they usually have hardeners of some degree, so a simple 10% bath of sodium thiosulfate will do if you can locate the bulk chemical.

I have written a paper called '"Recycling of Holographic Plates" which covers this topic, available to any forum readers if you PM me with an e-address to send it to.

Colin Kaminski · Post by **Colin Kaminski** » Thu Aug 06, 2009 3:51 pm

Ed, is that paper copyright free? I would like to post it to the forum.

Ed Wesly · Post by **Ed Wesly** » Fri Aug 07, 2009 2:44 pm

It never got published in print so I will e-mail you an electronic version.

holo_cyware · Post by **holo_cyware** » Sun Aug 09, 2009 3:28 pm

GOOD news: the plates I can get (ORWO LP2 and LP3) are apparently good for holography, as stated in the great book called "Silver-halide recording materials". It looks like the plates, "out of the box" are able to get a resolution of 2500 lines/mm. I know this is not enough at all for holography, but I plan to fix/reprocess them with the "Blyth" method.

I also stumbled across a box of 50 sheets (6x4 inch) of Kodak 400TMAX film (B&W). Is the gelatine on this film able to record a hologram? (thinking about reprocessing these sheets too).

holo_cyware · Post by **holo_cyware** » Tue Sep 22, 2009 5:51 pm

What I've actually got are ORWO spectral plates WP-3 and WP-2. (pancromatic).

Does anyone has a spec sheet for these or something? They are supposedly fine grain, slow plates, but I need to know the resolution.

JohnFP · Post by **JohnFP** » Tue Sep 22, 2009 7:42 pm

Page 331 should have your answer for WP-3 anyway.

http://articles.adsabs.harvard.edu//ful ... 1.000.html

holo_cyware · Post by **holo_cyware** » Tue Sep 22, 2009 8:29 pm

So it just falls within regular "foto resolution" then. Far away from the 3000 lines minimum I was hoping for. On the other hand, having their test done on a real holographic plate I doubt it would render consistent results with the manufacturer claimed resolutions. The hologram must be the ultimate test.

Question is, would the gelatin layer be suitable for resensitizing? I guess it would.

JohnFP · Post by **JohnFP** » Wed Sep 23, 2009 9:49 am

That's a good question on the gelatin layer quality. You could try it. Worth if if you have a lot of the plates. I always wanted to buy some really professionally coated plate to strip the silver out and resensitize with DCG.

Hey Ed, at the resolving power of 125 lines per mm for that stuff, what would be the maxium spacing (degrees) between the object and reference beam in a transmission set up that would give a grating?

holo_cyware · Post by **holo_cyware** » Wed Sep 23, 2009 1:08 pm

Well,

as I've got quite a lot of these plates (probably in the order of hundreds) the'd better work.

The thing is, I'm willing to give away some of them to the best DCG holographers here for testing (you, Duchelm, Dave Battin, Danny Bee, Joe Farina and others).