FEG (ferric gelatin) holograms
Posted: Sun Dec 14, 2008 9:30 am
Thanks to a_k (thank you, Ahmet!) I got access to a 405nm (Bluray) laser diode. Though its coherence length is rather limited, it is definitely a very exciting wavelength for a great many holographic recording materials.
Among the things I tried were ferric systems, based on ferric ammonium citrate and ammonium ferric oxalate.
I started with a similar mixture as the one described in the CHIBA system (see http://spitbite.org/carbon/papers/TheChibaSystem.pdf and http://holographyforum.org/phpBB2/viewt ... a&start=15). The exposed layer was “fixed” for 30s in a ~1% hydroxy peroxide solution (I actually diluted a peroxide household bleach). Then the plate was washed and put in a (water) swelling bath. Subsequently the usual alcohol dehydration took place, followed by hot air drying. So this is exactly the same processing as for DCG.
Although speed was not as high as with DCG (ammonium dichromate), the FEG holograms revealed an excellent DE. So the good news is, ferric compounds may successfully replace DCG – at least at a blue-violet recording wavelength. In an analogy with DCG we may call these materials FEG (= ferric gelatin).
The holograms look very similar to DCG. I actually believe they may even perform better than DCG when it comes to issues like noise and resolution. Ferric systems seem to differ from DCG with regards to their specific absorption spectra. Ferric ammonium citrate and ferric ammonium oxalate seem to be sensitive from UV to blue only.
One might wonder about spectrally sensitized ferric systems also...
The highest speed levels were achieved with ammonium ferric oxalate. These layers were well on par with ammonium dichromate-DCG. One drawback was the short shelf life of the sensitizing solution.
I assume more ferric components ought to be tested, I am particularly thinking of ferric oxalate and alike.
Among the things I tried were ferric systems, based on ferric ammonium citrate and ammonium ferric oxalate.
I started with a similar mixture as the one described in the CHIBA system (see http://spitbite.org/carbon/papers/TheChibaSystem.pdf and http://holographyforum.org/phpBB2/viewt ... a&start=15). The exposed layer was “fixed” for 30s in a ~1% hydroxy peroxide solution (I actually diluted a peroxide household bleach). Then the plate was washed and put in a (water) swelling bath. Subsequently the usual alcohol dehydration took place, followed by hot air drying. So this is exactly the same processing as for DCG.
Although speed was not as high as with DCG (ammonium dichromate), the FEG holograms revealed an excellent DE. So the good news is, ferric compounds may successfully replace DCG – at least at a blue-violet recording wavelength. In an analogy with DCG we may call these materials FEG (= ferric gelatin).
The holograms look very similar to DCG. I actually believe they may even perform better than DCG when it comes to issues like noise and resolution. Ferric systems seem to differ from DCG with regards to their specific absorption spectra. Ferric ammonium citrate and ferric ammonium oxalate seem to be sensitive from UV to blue only.
One might wonder about spectrally sensitized ferric systems also...
The highest speed levels were achieved with ammonium ferric oxalate. These layers were well on par with ammonium dichromate-DCG. One drawback was the short shelf life of the sensitizing solution.
I assume more ferric components ought to be tested, I am particularly thinking of ferric oxalate and alike.