Holographyforum.org / holowiki.org

[quote="dannybee"]thanks Martin and Dinesh,
whats the formula & process for FEG systems and are the chemical easy to find?[/quote]

Ferric ammonium oxalate (FAO) and ferric ammonium citrate (FAC - it must be the green one, not the brown kind) should do the job in most cases.
Ferric chloride is a bit trickier to use.

[quote="jsfisher"]I'll plug the wiki any chance I get: http://holoinfo.no-ip.biz/wiki/index.php/Experimenter%27s_Corner#Ferric_Ammonium_Oxalate[/quote]

You might add this link: http://holoforum.org/oldforum/viewtopic.php?f=2&t=6553

I'll plug the wiki any chance I get: http://holoinfo.no-ip.biz/wiki/index.php/Experimenter%27s_Corner#Ferric_Ammonium_Oxalate

thanks Martin and Dinesh,
whats the formula & process for FEG systems and are the chemical easy to find?

[quote="dannybee"]" I've tried DAS, diazidostilbene-2,2'-disulfonic acid salt"

Is there any formula for this?[/quote]
Not to my knowledge. I simply added as much DAS from a stock solution to the gelatin solution I could.

Light absorption seems to be in the UV - blue-violet spectral range only.
Otherwise, the liquid processing is similar to FEG systems. One pecularity though is that on the laser exposure the layer slightly darkens (but that effect vanishes after the liquid development).

[quote] and what is the process? sites or papers talking about the process?[/quote]
Kosar's book (Light-sensitive systems: chemistry and application of nonsilver halide photographic processes) extensively treats diazo processes.

[quote="Dinesh"]I remember that at the time you thought that this exposure was a bit on the high side.[/quote]

Yes, compared to 405nm exposures. Perhaps dealing with FAC or other ferric salts may improve the situation for blue recordings.

[quote="Martin"]And in regard to speed of ferric systems, relative humdity in the recording environment may play some role. Switching to summer mode, the increased RH in my lab (currently ~ 80% compared to ~40% during the winter season) seems to enhance photospeed of FEG systems.[/quote]
I've just looked up my records and I see that I recorded it in March 16th 2012. The humidity on that day was 43% and the temp was 70 F ( ~20C). I have no efficiency figures, since it was a display.The notes for the hologram show that the power at the plate was 2.1 mW and I initially tried 60 seconds, which I noted as "almost nothing", then I tried 120 seconds and I noted that it was "good". I remember that at the time you thought that this exposure was a bit on the high side.

[quote="dannybee"]" I've tried DAS, diazidostilbene-2,2'-disulfonic acid salt"

Is there any formula for this? and what is the process? sites [/quote]
We tried using diazo dyes at POC sometime around 1987. As I remember, the holograms were a bit weak and it was abandoned. Probably by now, techniques have improved.

[quote="dannybee"]papers talking about the process? [/quote]
http://www.benthamscience.com/mats/samples/mats%201-1/Asit%20B.%20Samui.pdf
http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA076203
http://en.wikipedia.org/wiki/Azobenzene (go halfway down to "Photoinduced motions"
http://www.dtic.mil/docs/citations/ADA297569

" I've tried DAS, diazidostilbene-2,2'-disulfonic acid salt"

Is there any formula for this? and what is the process? sites or papers talking about the process?

[quote="Dinesh"]True. I did a test for Martin some time last year with FEG using a 457 and the results were quite good. Did not try 405, but I think for FEG, the bluer the better. By the way, the hologram is still visible with no lamination since September or so.[/quote]

That doesn't sound that bad.
When it comes to 457nm recordings I still think that there are some ferric compounds out there that have far better absorption at that wavelength than FAO. For example ferric ammonium citrate (FAC), the "green" kind, would be something to try.

And in regard to speed of ferric systems, relative humdity in the recording environment may play some role. Switching to summer mode, the increased RH in my lab (currently ~ 80% compared to ~40% during the winter season) seems to enhance photospeed of FEG systems.

[quote="Martin"] Actually, ferric ammonium oxalate sensitized gelatin (FEG) seemed to provide better speed than ammonium dichromate sensitized DCG.

[/quote]
True. I did a test for Martin some time last year with FEG using a 457 and the results were quite good. Did not try 405, but I think for FEG, the bluer the better. By the way, the hologram is still visible with no lamination since September or so.