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by **soda** » Sat Apr 13, 2019 11:28 am

Milky haze is sign of grain grows due to recrystalization - something is wrong. You are right, reaction byproduct (KNO3) can increase tendency for recrystalization, this should be removed by freezing and thawing. Also high temperature and long time are favorable condition for recrystalization and cause wide grain size distribution, unwanted for holography. Do you have some results?

by **Grayham** » Mon Apr 08, 2019 4:03 pm

soda wrote: ↑Wed Mar 27, 2019 9:38 am I found that water quality have great impact on the emulsion. When I have used deminaralized water from supermarket instead distilled water, resulting emulsion was noticeably worse. If milky haze appears in AgNO3 solution something is wrong.

Hi Soda,
I'm using a variation of your process and have noticed a couple of times a milky haze when the plates have dried. Normally in thicker areas if the coats uneven. I put my problems down to insufficient washing of the gelatin after reaction. I get less haze when I go through a proper wash cycle.
I use deionised water.

Grayham

by **soda** » Wed Mar 27, 2019 9:38 am

I found that water quality have great impact on the emulsion. When I have used deminaralized water from supermarket instead distilled water, resulting emulsion was noticeably worse. If milky haze appears in AgNO3 solution something is wrong.

by **soda** » Thu Jan 10, 2019 5:04 pm

I'm sorry for that, I will correct it. Isocyanine is 1,1′-Diethyl-2,2′-cyanine iodide. Other synonym: 1-Ethyl-2-[(1-ethyl-2(1H)-quinolinylidene)methyl]quinolinium iodide, Decynium 22, Pseudocyanine iodide, Pseudoisocyanine iodide.
It is very strong sensitising dye for green 532nm, does not cause desensiting or fog, but if I add too much, unfavorable proportion reference to object beam results in dim hologram, due to strong absorption. Less is better, 1/4 of pinacyanol amount is enough. Alternative is quinaldine red (Synonym: 2-(4-Dimethylaminostyryl)-1-ethylquinolinium iodide), cheaper, non-toxic and easy to obtain. I mainly use pinacyanol alone, my green laser is stronger and result in very bright green in comparable exposition times as red.

by **dannybee** » Thu Jan 10, 2019 4:20 pm

I would think "1,1′-Diethyl-2,2′-cyanine iodide" would work in place of Isocyanine, am I correct?

by **Grayham** » Sat Jan 05, 2019 8:28 am

Hi Soda,

I just wanted to say thank you for posting this, it's much appreciated.
I had been looking at the Silver Cross paper by Han's and trying a few experiments.
But to have your tried and tested formulae based on the "silver cross" written out like this, is invaluable.

Thank you very much
Grayham

by **soda** » Mon Dec 31, 2018 10:05 am

Plasma cleaning is really effective. The glass is placed on grounded metal sheet and scaned by X-Y ploter to achieve large surface. The plasma is created between the glass and thin insulator with burried electrode (defunct peltier cooler) connected to HV from induction coil. IMG_... is an image of water droplets on grease contaminated glass. Left is after treatment and right is untreated. The water contact angle is dramatically decreased. DBD plasma driver: IC1 is PWM modulator and opens Q1 MOSFET. Current start to flow thought automotive inductor (closed core recommended) connected between 1 and 15, then the IC1 closes the Q1, the inductor start to oscillate with C3, on secondary induces high voltage, which cause air breakdown and create the plasma. Good ventiltion is needed, O3 is dangerous.

by **Sergio** » Mon Dec 31, 2018 9:20 am

Thank you Soda. Your suggestion of plasma glass cleaning is wonderful because we eliminate the nasty acid and Piranha solution, etc. We believe that silver halide is a good way to do the MASTER because the photopolymer is relatively insensitive to pulsed lasers, to reduce the costs, is better to have the option of a normal pulsed laser instead specialized pulsed ones.

Even for a tiny master is necessary a pulsed laser for commercial applications...

As for applying we may simply print the emulsion onto the glass. The oxygen insensitivity is another plus got the master quality because of the Fourier plane very space limited. I don't believe that someone will find that Russian dyes anywhere, makes nonsense because we have plenty of huge selection from Germany.

by **Martin** » Sun Dec 30, 2018 2:01 am

Very interesting, thanks for posting!

Similar approaches can be found in RU 2292573 (http://russianpatents.com/patent/229/2292573.html) and DE 10252119 (https://depatisnet.dpma.de/DepatisNet/d ... 10252119A1). At ESPACENET you might get a (machine) translation.

The Russian patent lists some interesting spectral sensitizers. The question though would be, where to get them.

The German patent adds sulfur/gold sensitization to ascorbate reduction sensitization à la Jeff Blyth. So photo speed ought to be enhanced further.

by **soda** » Sat Dec 29, 2018 3:50 pm

Finally, I have to compile formula for preparation of ultra fine grain silver halide emulsion for color holography, based on Silver Cross project. Any comments, experiments and improvements are greatly welcomed and will be implemented in future revisions of the attached document. Despite of really good results, there is still room for improvement in sensitization, alternative ways of developement procedure and plate preparation.
Have a fun... with stable fringes!
And happy new year!

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