Diazo (Speedball) gelatin hologram

Dichromated Gelatin.
Martin
Posts: 121
Joined: Sat Apr 04, 2015 2:36 am

Diazo (Speedball) gelatin hologram

Post by Martin » Mon Sep 27, 2021 2:17 am

Diazo-gelatin (DIAG). This is a follow-up to: https://holographyforum.org/forum/viewt ... 9&start=10
Thanks by the way, vasimv, for pointing to SPEEDBALL.

It appears that their diazo sensitizer for screen printing can be used to make holograms just like DCG. It's easy to use and  simple to add spectral sensitizatio to the system. Moreover, it's available in many countries.
So e.g. it can be bought from Amazon etc. This is the specific diazo sensitizer: www.speedballart.com/wp-content/uploads ... l_2021.pdf
It's on page 4, item #9, product #004578, "SPEEDBALL DIAZO SENSITIZER".
The MSD (/www.dick-blick.com/msds/DBH_SDS_433041002.pdf) lists the following chemicals:
4-Diazodiphenylamine / formaldehyde condensate hydrogen phosphate complex
P-diazoldiphenylamine polymer
Phosphoric acid

I assume most things doable with DCG can be done with DIAG, volume reflection, surface relief holograms that is.
I previously tried another diazo, "D.A.S". See: https://holographyforum.org/forum/viewt ... 0&start=20
With D.A.S.-gelatin I could make reflection holograms at 405nm that had the typical DCG look. However, with that diazo it becomes difficult to record holograms at longer wavelengths.
The SPEEDBALL sensitizer (SPS) seems to be compatible with a great many dyes. A Canon patent (US 3778274), "Spectrally sensitized diazo materials", deals with very similar diazo materials ("diazo diphenylamine derivatives such as p-diazo diphenylamine sulphate").
In regards to spectral sensitization it points out:

"Conventional sensitizing dyes, such as those used for sensitizing silver halides and zinc oxide may be used in this invention. Representative examples thereof are: triphenylmethane dyes such as Brilliant Green, Crystal Violet and Acid-Violet 6B; rhodamines such as Rhodamine B, Rhodamine 6G, Rhodamine G Extra, Sulforhodamine B and First-Acid-Eosine G; xanthene dyes such as Eosine S, Eosine A, Erythrosine, Phloxine, Rosebengale and fluorescein; thiazine dyes such as methylene blue, methylene green, methylene violet, methylene azine, thionine blue, toluidine blue, and Thiocarmine R; acridine dyes such as acridine yellow, acridine orange and Trypaflavin; quinoline dyes such as pinacyanol and cryptocyanine; quinone dyes such as alizarine, alizarine red S, quinizarine; cyanine dyes; aryl methane dyes such as Erythrosine 2Na, Rhodamine B 500, Fanal Pink B, Rhodamine 6GDN, and auramine; polymethine dyes such as 3, 3'-diethylthiacarbocyanine iodide; azo dyes such as Eriochrome blue black R, azo methine dyes such as bis(p-dimethylamino benzal) azine; carbonyl dyes such as Solway Ultrablue B, arizaline cyanine green GWA; and phtholocyanine dyes such as Segnale light turquoise NB."
II guess RGB holograms should be possible on such grounds. I've successfully tried methylene blue at 650nm in a SPB-gelatin mix.

Incidentally, there's a 1980 paper by Gladden, "Grating formation in diazo gelatin". Interestingly, he based his tests on very much the same diazo as the one in the SPB sensitizer. He exposed the diazo-gelatin layers at 488nm (625mJ/cm2) and processed them analog to DCG.
For coating I used 4.0g of a 10% gelatin solution to which I had pipetted 1 drop from the SPB stock solution. The stock solution was prepared by simply filling up the original SPB sensitizer bottle with water.
After the laser exposure it's best to "develop" the DIAG layer in an alkali solution. The nature of that solution doesn't seem to matter much - as long as it doesn't attack the gelatin.

I should perhaps mention one downside: after processing, that's-to-say, after alcohol dehydration, a slightly yellow-brown tint persists. Its strength directly depends on the amount of SPB sensitizer in the layer. I've yet to find a solution to that problem.

jrburns47
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Location: Oyster Bay, NY

Re: Diazo (Speedball) gelatin hologram

Post by jrburns47 » Mon Sep 27, 2021 3:29 am

Photos😊?!

Joe Farina
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Re: Diazo (Speedball) gelatin hologram

Post by Joe Farina » Mon Sep 27, 2021 9:34 am

Wow, thanks for reporting your tests. This may have real potential.

The patent lists an impressive number of dyes, and on the face of it, RGB sensitization looks promising. Of course, sensitivity at given wavelengths is of primary importance. Please let me know if I can help with some tests.

In my opinion, the first thing which needs to be looked at is available laser wavelengths. Reasonably affordable (say ~<$3000 each), holographically suitable wavelengths, and at what power. I would be interested in knowing if anything has happened lately with regards to blue. People seemed to have adopted Sapphire 488's to an extent. Whether or not that particular Sapphire can make holograms is not perfectly clear, but many people, including me, have one. The Melles 457 is still a rare and expensive option.

The "green" question seems to be gone forever, the Coherent lasers and equivalents are perfect for holography, and at a good price. So, the green target wavelength should be 532nm.

Red is something of a problem still, but I vote for HeNe at 633. They are still available, and will probably remain so. Even the large SP-127's can be had for a reasonable price, for ~40mW at 633. So I would vote for 633 being the target wavelength for red (and the sensitivity needing to be high at this wavelength, to accommodate a max power of 40mW).

I might recommend the development of a simple test for sensitivity ("speed") at a given set of wavelengths. This may not be the simplest thing in the world, but it would be very helpful considering that long list of dyes (!)

Since 532 is firmly established (even with some inexpensive eBay lasers) how about testing speed by exposing with an opaque object resting on the emulsion then checking solubility of the exposed vs. unexposed areas. Just a thought.

Martin
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Re: Diazo (Speedball) gelatin hologram

Post by Martin » Tue Sep 28, 2021 10:11 am

Of course, any testing with this material would be highly appreciated.

Yes, the laser question really is of great importance. It would be nice to know up to what wavelength holograms can be made - without any spectral sensitization. The two laser modules I have are doing OK at rather low wavelengths (405 and 445nm). Unfortunately their power is pretty moderate o say the least (5mW only!). I'd love to learn what could be done with this diazo stuff with more laser power. I'd guess 488nm still is a pretty efficient wavelength for this material.

Furthermore, I'd expect to find alternative ways of enhancing speed - say by adding new ingredient(s) or modified processing.

Din
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Re: Diazo (Speedball) gelatin hologram

Post by Din » Tue Sep 28, 2021 12:36 pm

Joe Farina wrote:
Mon Sep 27, 2021 9:34 am
I might recommend the development of a simple test for sensitivity ("speed") at a given set of wavelengths. This may not be the simplest thing in the world, but it would be very helpful considering that long list of dyes (!)
There is no actual sensitivity for dcg, as opposed to silver halide, because the modulation is dependent on a wide variety of parameters, including the bloom strength of the gelatin, the emulsion thickness, the proportions in the mix etc etc. I used to expose from 30 mW to 300 mW and more, depending on the application. One feature of display holograms is that it's necessary to maximise brightness, which does not necessarily mean maximising efficiency - there are issues of the photopic efficiency as well as bandwidth; bandwidth issues make it necessary to expose at the lower end, sacrificing efficiency for brightness. The reason is that the actinic reactions in silver halide are dependent on precise energy transfers, while the actinic reaction of dcg ranges over a greater range. The actinic reaction of silver halide is dependent on redox potentials, whereas the actinic reactions of dcg are dependent on the Kramers Kronig relations. Here (below) is the range of sensitivities for dcg exposed at 441nm for a 0.7 m emulsion.

As far as a simple test, my solution would be to add various concentrations of a specific dye to the emulsion, keeping all else constant (emulsion depth, bloom strength etc) then record two-beam gratings at various exposures and measure the DE. This is basically what we did for Martin and Sergio about 15 years ago for their polymer. I would then plot the DE as a function of exposure, which i would expect to be non-linear.
sensitivity.jpg
sensitivity.jpg (124.24 KiB) Viewed 3251 times

Din
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Re: Diazo (Speedball) gelatin hologram

Post by Din » Tue Sep 28, 2021 12:39 pm

Martin wrote:
Tue Sep 28, 2021 10:11 am

Yes, the laser question really is of great importance. It would be nice to know up to what wavelength holograms can be made - without any spectral sensitization.
Here you go! I assume that 'without any spectral sensitization' means you are going to add ammonium dichromate :D
dcg sens208.jpg
dcg sens208.jpg (192.19 KiB) Viewed 3251 times

Martin
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Re: Diazo (Speedball) gelatin hologram

Post by Martin » Wed Sep 29, 2021 8:04 am

Din wrote:
Tue Sep 28, 2021 12:36 pm
As far as a simple test, my solution would be to add various concentrations of a specific dye to the emulsion, keeping all else constant (emulsion depth, bloom strength etc) then record two-beam gratings at various exposures and measure the DE. This is basically what we did for Martin and Sergio about 15 years ago for their polymer. I would then plot the DE as a function of exposure, which i would expect to be non-linear.
sensitivity.jpg
That looks like a really good start. In addition, I would also keep an eye on "speed enhancing techniques" that focus on the spectral sensitizer though. You'll certainly recall Jeff Blyth's TMG-DCG system. Compare this with Graube's approach, who simply added a dye to the DCG solution.

Unfortunately, with the diazos we cannot rely on a long tradition of spectral sensitization (compared with say, silver-halide emulsions). The above mentioned Canon patent seems to be rather an exception. I doubt that spectral sensitization would be a big thing for the screen-printing community.

Martin
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Re: Diazo (Speedball) gelatin hologram

Post by Martin » Wed Sep 29, 2021 8:07 am

Din wrote:
Tue Sep 28, 2021 12:39 pm
Here you go! I assume that 'without any spectral sensitization' means you are going to add ammonium dichromate :D

Yeah, absolutely ;)

Erik
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Joined: Mon Mar 01, 2021 11:06 am

Re: Diazo (Speedball) gelatin hologram

Post by Erik » Fri Oct 22, 2021 6:49 pm

Extremely exciting!

If my assistance would be useful in developing the technology, I would love to help.
I have several dyes and lasers available and time in the next few weeks for experiments.
Dyes on hand: erythosine, rhodamine B, safranin O, and methylene blue.
Lasers on hand: 405, 445, 473, 488, 532, 568. No red unfortunately, although I am working on it.

Any more detail in how the coating was performed, especially thickness? Temperature of the emulsion prior to coating? Exposure time vs area? I see you tried MB, what concentration? The aforementioned dyes are much more soluble if the emulsion pH is above 7. Was any pH control performed prior to emulsion coating?

Martin
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Joined: Sat Apr 04, 2015 2:36 am

Re: Diazo (Speedball) gelatin hologram

Post by Martin » Sun Oct 24, 2021 10:27 am

Erik wrote:
Fri Oct 22, 2021 6:49 pm
If my assistance would be useful in developing the technology, I would love to help.
Please do. Any help will be greatly appreciated. Given the scarce experience with holographic diazo gelatin materials, this is almost pioneering work.
Lasers on hand: 405, 445, 473, 488, 532, 568.
Sounds impressive. For a start it might be good to evaluate the sensitivity of SPB without adding any dye. At 405 and 445nm it may be not far from DCG or ferric gelatin (FEG) systems. I now believe it might even respond to 532nm. Having only a small 10mW 405nm diode of a few millimeters of coherence length at best (not to mention the problems with mode hops) I would love to know the speed of the SPB material at that wavelength. In my opinion the 405nm is pretty much underestimated in regard to its use for display work.
Any more detail in how the coating was performed, especially thickness?
In the 10 - 20um range, Mayer bar or veil coating.
Temperature of the emulsion prior to coating?

~50°C.
Exposure time vs area?


~90s for a 5 x 10 cm area, exposed with a 5mW (Liti) diode @ 445nm. Culinary (Gelita, pig skin) gelatin. It might be interesting to see how different kinds of gelatin or perhaps other "colloids" like PVOH, gum arabic etc. perform.
I see you tried MB, what concentration? The aforementioned dyes are much more soluble if the emulsion pH is above 7. Was any pH control performed prior to emulsion coating?
No pH control. With MB I only made a few batches (2 drops from a 1% MB solution into my above formula). One batch with MB + Disodium EDTA.
Unfortunately, I have very limited access to my lab currently. But I would like to test pinacyanol for HeNe exposures.
Adding a plasticizer/humidifier (glycerol most often) to the coating solution seems to be beneficial.

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