Some facts from my notes on DCG January 23 2004 at 9:34 PM
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I am finding out that you can literally use 100's of combination of variables to make a DCG but for every variable you change there is an effect. The old cause and effect philosophy. These are some of my beliefs with DCG from my notes, studies and applications.
If one increases temperature the emulsion lays thinner.
If the plate’s temperature at time of coating is increased emulsion lays thinner.
This has nothing to do with the wire rod method or vail method as I studied those independently.
*When the emulsion is thinner the concentration amount of Dichromate is less per thickness deep. Although thinner emulsion is supposed to require less exposure I believe the decreased weight of the Dichromate per thickness supersedes the thinness. Thus decreasing thickness without increasing concentration of DC actually requires a longer exposure. This may not be a linear function and may only apply at some concentration range at some thickness range, not sure yet. I do know that the plates I just made with the #24 wire rods and I got back up to my coating temperature of 115 degrees F. yielded a significantly thinner and very, very less opaqueness of the emulsion. I had a plate I made last week that was left over and I compared that one to the one I made tonight and the older plate which was coated at about 85 degrees with the same wire rod was a lot, lot yellow-er when I looked though it. My formulas remained the same and my processing was that same. The longer exposure I did with the thinner plates the brighter the holograms.
*Then you have processing temperatures and concentrations especially the one around 45 - 60% alcohol. I think I already gave findings on these.
Then you have how young or old the emulsion is and its relationship to exposure time and the concentration of hardener in the fixer.
Then you have how hard the fixer makes the emulsion because of the concentration or how long you need to keep the hologram in each of the alcohol baths and what their temperature is. Not all baths should be the same temperature.
I am not trying to scare anybody into not pursuing DCG holography but I am pointing out fact that I have found and will try to write a complete summary/paper in the near future.
"Thus decreasing thickness without increasing cncentration of DC actually requires a longer exposure. This may not be a linear function "
Good observation! While I try to stay away from the word "photon", I find that it may be the best way to think this through. The exposure creates cross linking sites where the photon hits a Cr[6+] causing it, through a chain of reactions, to reduce to Cr[3+]. This Cr[3+] then acts as a catalyst for the polymerisation of the gelatin ("cross linking"). Now, not all the photons that enter the gelatin emulsion "hit" a Chrome-6 ion and not all that hit a Chrome-6 ion have enough energy to start the chemical chain of events to reduce Chrome-6+ to Chrome-3+. Hence there is a proportionality ratio:
number of photons going in/number of photons causing reaction
This is known as the "capture cross section" Sort of, how many bullets you fire at the target compared to how many hit it. This cross section pretty much determines your exposure and, most important, is a volume effect. Thus when you reduce the thickness, you reduce one dimension of a cube but not the other two so you reduce the volume of the cube by whatever proportion you reduced the thickness and also the capture cross section. Fewer capture events means more photons needed to create the same effect.
Tomorrow: The Relativistic Quantum Field Effects if DCG. I'm joking! I'm joking! (Actually "quantum" is another word I try to steer clear from.)
<... Tomorrow: The Relativistic Quantum Field Effects if DCG. I'm joking! I'm joking! (Actually "quantum" is another word I try to steer clear from.) ...>
Can't wait to read this.
Maybe can help to make hologram of a cat (the schrodinger's cat, of course )
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