Obligatory picture of coins.
With motion, and lab pic: https://imgur.com/gallery/O88yFQZ
(I call it "Sorry, you can't take a shower right now.")
Made more or less according to the Integraf instructions. Some banding at the top, I think due to my setup and light reflecting off the counter and coupling into the edge of the plate while I held the book before exposing the hologram.
Hoping to do more soon, but things are pushed back due to a medical emergency in the family.
First Light with Integraf Kit
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Re: First Light with Integraf Kit
Surprisingly bright! I wonder where the color came from. Did you alter JD-4 processing? Normally, PFG-03M processed with JD-4 reconstruct in red.
Re: First Light with Integraf Kit
Could it be overexposed? This would shrink the film.
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Re: First Light with Integraf Kit
Ah, right. I left out an important detail. There's some sort of shortage due to COVID19, so the standard kit is shipping with PFG-01 and JD-2. Would you expect JD-2 holograms to reconstruct in green?
Re: First Light with Integraf Kit
Yes. Very nice hologram for a first go at it! You're certainly on the right track.
Re: First Light with Integraf Kit
Yes. The green shift is caused by shrinkage of the emulsion. The fringes recorded in the volume of the emulsion act as mirrors (not exactly, but it is a useful model). The distance between the mirrors is determined by the wavelength used in the recording process. The distance also determines what range of wavelengths contributes to the reconstructed image. When you record the hologram and shrink the emulsion, the distance between mirrors gets smaller, which is a somewhat equivalent to recording with a shorter wavelength. A decent shrinkage shifts reconstruction from red to greenish, as in your photograph.maskedkoala wrote: ↑Fri Jul 24, 2020 10:40 am Would you expect JD-2 holograms to reconstruct in green?
The JD-2 developer is also known as CWC2, see http://holowiki.nss.rpi.edu/wiki/Ewesly ... JD-2,_JD-3
The urea in the recipe softens the emulsion. I believe this helps the shrinkage, although it is mostly the bleach that is responsible for the shrinkage.
The JD-2 bleach is a type of pyrochrome recipe, see http://holowiki.nss.rpi.edu/wiki/Ewesly ... Pyrochrome
It is the solvent bleach, which means that some materiel in the developed emulsion is dissolved and washed away. As some material is lost, it leads to shrinkage.
By the way, you are lucky you got PFG-01. It lasts much longer than PFG-03M normally included in the kit. Moreover, it is much more sensitive than PFG-03M.
The last note: do not forget that potassium dichromate in the bleach is dangerous chemical. Handle it with care. Read the MSDS information available at Integraf web. Do not flush it into the kitchen sink, never ever.
Re: First Light with Integraf Kit
Yes, I agree the green shift is caused by shrinkage. But, the cause of the shrinkage may be overexposure, or it may be over-development. Basically, the emulsion is overhardened. I don't think just using CWC2 causes shrinkage, that is, the shrinkage is not caused simply by using CWC2. I've attached a hologram made by a student on pfg-01 using CWC2, or JD-2. As you can see, it reconstructs at the same wavelength it was recorded with - 633nm.
Funny thing is, this is the Van Ranesse bleach, which I used to use. But, Alec's bleach uses sodium bisulphate. I used concentrated sulphuric acid.
Re: First Light with Integraf Kit
Here’s a link to a thread that explains how to neutralize the potassium dichromate issue that Petr Lobaz pointed out:
https://www.photrio.com/forum/threads/p ... -uk.44053/
Read the Dec 1 2008 msg from Alan Davenport and the subsequent one from Ole.
If you need chemicals, a good source is Photographers Formulary:
http://stores.photoformulary.com/
They’re website is down for “maintenance” right now but they told me that they’ll be back up soon. You can also get some perfectly usable chemicals from eBay.
https://www.photrio.com/forum/threads/p ... -uk.44053/
Read the Dec 1 2008 msg from Alan Davenport and the subsequent one from Ole.
If you need chemicals, a good source is Photographers Formulary:
http://stores.photoformulary.com/
They’re website is down for “maintenance” right now but they told me that they’ll be back up soon. You can also get some perfectly usable chemicals from eBay.
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- Joined: Mon Jun 29, 2020 10:24 pm
- Location: Florida
Re: First Light with Integraf Kit
Nice. You guys rock. Thanks for the excellent information.
From the wiki on CWC2:
However, looking back at the instructions from the kit, I think they were written for PFG-03M, and suggested a 10s exposure time. It looks like the sensitivity is an order of magnitude higher (or lower, depending on how you look at it, I guess) for PFG-01, so perhaps I over exposed by >~10X? Maybe the exposure time should have been more like 1s or less. (I guess someday I'll get a power meter and/or maybe do some exposure testing).
Besides the replay shift, are there any other negative consequences of overexposure? The results seem pretty solid, would they have been better with something closer to a 1s exposure?
On disposing the potassium dichromate: the recipe is 5 mg in 1000 mg of water, a ~0.5% concentration. Just to check my understanding: I should just mix the spent bleach with the spent developer, filter out the precipitate, then pour the liquid down the drain and throw the precipitate in the trash. Did I get that right?
From the wiki on CWC2:
Does "Chrome bleach" mean bleach with potassium dichromate? If so, it sounds like that's what happened.Follow with a ... 'Chrome bleach for change of replay wavelength in the reflection mode.
However, looking back at the instructions from the kit, I think they were written for PFG-03M, and suggested a 10s exposure time. It looks like the sensitivity is an order of magnitude higher (or lower, depending on how you look at it, I guess) for PFG-01, so perhaps I over exposed by >~10X? Maybe the exposure time should have been more like 1s or less. (I guess someday I'll get a power meter and/or maybe do some exposure testing).
Besides the replay shift, are there any other negative consequences of overexposure? The results seem pretty solid, would they have been better with something closer to a 1s exposure?
On disposing the potassium dichromate: the recipe is 5 mg in 1000 mg of water, a ~0.5% concentration. Just to check my understanding: I should just mix the spent bleach with the spent developer, filter out the precipitate, then pour the liquid down the drain and throw the precipitate in the trash. Did I get that right?
Re: First Light with Integraf Kit
Yes, "chrome bleach" is a potassium dichromate bleach.
Overexposure generally leads to lower contrast of fringes - parts of the emulsion that were intended to be "unexposed" get some exposure due to excess time, while the parts that were intended to be "fully exposed" are still "fully exposed". Lower fringe contrast generally leads to lower brightness.
The best thing to do is to make a proper exposure test. Make a paper card of the plate size and cut off one quadrant. Cover the plate in the "coins" setup and expose for 1 second. With laser covered, rotate the card 90 degrees so that new part of the plate is uncovered, and make exposure 2 seconds long. Repeat for exposure 4 seconds and 8 seconds. Now you have, in fact, four holograms on a single plate, each one with different exposure. Develop and watch how fast it turns black. If I remember correctly, CWC2 should not be too fast, I would expect turning black in, say, 30 to 60 seconds. If it goes black faster, it is overexposed. If it is not black after 2 minutes, it is underexposed. You can judge blackness visually: when looking through the plate, you should see the safelight, but not the trays. Bleach the plate as usual. Dichromate bleach acts quite fast, the plate should be clear within, say, 30 seconds. If you see traces of black after two minutes, I guess the bleach lifetime is over.
Dichromate disposal: first of all, keep using the bleach until it works. If you make a few holograms a week, it can last for years.
I do not feel qualified to give decisive recipes how to properly dispose the dichromate bleach. It seems that adding sodium metabisulfite should do the trick, the colour should change from orange to blue. Anyway, I would dispose the chemicals at local dump site.
Overexposure generally leads to lower contrast of fringes - parts of the emulsion that were intended to be "unexposed" get some exposure due to excess time, while the parts that were intended to be "fully exposed" are still "fully exposed". Lower fringe contrast generally leads to lower brightness.
The best thing to do is to make a proper exposure test. Make a paper card of the plate size and cut off one quadrant. Cover the plate in the "coins" setup and expose for 1 second. With laser covered, rotate the card 90 degrees so that new part of the plate is uncovered, and make exposure 2 seconds long. Repeat for exposure 4 seconds and 8 seconds. Now you have, in fact, four holograms on a single plate, each one with different exposure. Develop and watch how fast it turns black. If I remember correctly, CWC2 should not be too fast, I would expect turning black in, say, 30 to 60 seconds. If it goes black faster, it is overexposed. If it is not black after 2 minutes, it is underexposed. You can judge blackness visually: when looking through the plate, you should see the safelight, but not the trays. Bleach the plate as usual. Dichromate bleach acts quite fast, the plate should be clear within, say, 30 seconds. If you see traces of black after two minutes, I guess the bleach lifetime is over.
Dichromate disposal: first of all, keep using the bleach until it works. If you make a few holograms a week, it can last for years.
I do not feel qualified to give decisive recipes how to properly dispose the dichromate bleach. It seems that adding sodium metabisulfite should do the trick, the colour should change from orange to blue. Anyway, I would dispose the chemicals at local dump site.