JD4 and PFG-03M Developer/Exposure tradeoff

ajcleary · Post by **ajcleary** » Wed May 07, 2008 3:31 am

Hello All,

Setup:
I recently made a batch of single-beam reflection holograms using year-old PFG-03M 2.5"x2.5" plates and year-old JD4 developer (The part A was barely yellow, not brown). I used a 6mW HeNe laser (measured on a Scientech thermopile power meter) and a spatial filter to clean and expand the beam. Using the power meter I determined an exposure time of ~18 seconds to acheive 3mJ/cm^2, as recommended on the data sheet.

Object:
The object was a small dagger/letter opener with a shiny blade and brass hilt, next to a piece of relatively matte silver chain mail. The plate was laying directly on the scene, emulsion down, underneath everything is black felt.
Developing
I developed for 10 seconds (plate goes almost immediately black), rinse, bleach until clear +10 sec, rinse, photoflo

Results:
I beleive my table is stable - the holograms all came out very sharp, but not very bright. I am looking for ways to increase the brightness, and the only thing I haven't really played with is the developing time.

Questions:

1) I have read that JD4 increases sensitivity (or speed?) 10x, so does that mean I only need to expose ~1.8 sec? With a shorter exposure, would this lead to a longer developing time (see #2)? What is the result of over-exposure?

2) I have read of people developing PFG-03M/JD4 for 30 sec, 1 min, even 2 min. Would increasing the developing time increase brightness? What improvements might I see from increasing developing time?

3) The plates and chemicals are a year old - this isn't helping I'm sure. They were both stored in near-refrigerated conditions, the plates in the rigid black shippin container. Does anybody have any experience with old plates and developer, with relation to brightness? I plan to mix up a next batch of JD4 this weekend and see if that helps.

4) If I put the objects on a white card instead of the black felt, would that improve brightness of the whole hologram?

I know the best answer is to "just try it", and I probably will this weekend. But if somebody has some experience/advice then hopefully you can steer me in the right direction!

Sorry for the long post, but I look forward to any advice.

Colin Kaminski · Post by **Colin Kaminski** » Thu May 08, 2008 1:26 am

Great post! You provide all of the right information. Can you try an exposure test? There is a chance the plates are fogged. I know there were some threads about it and Michael got to the bottom of it I believe. I was hoping he would see this. I have only used pfg-03 a few times.

http://www.holowiki.com/index.php/Exposure_Tests

You are not the first person to complain that their PFG-03 goes black quickly.

ajcleary · Post by **ajcleary** » Fri May 09, 2008 1:03 am

Thanks for the reply, Colin! I tried doing a test exposre once before I knew what I was doing, but it sounds like it might be worth doing it again. This weekend I'll give it a shot and we'll see what happens.

Also on a related note, I heard from Alec Jeong at Integraf and he had the following tip for using older plates:

"By the way, with older PFG-03M plates, here's a tip: Right after exposure and just prior to developing the plates in the JD-4 developer, very gently presoak the plates in pure distilled water for about 10-15 seconds. Your holograms will come out quite clear and vivid. We did this with 2.5 year old plates and the results were quite stunning. Make sure the water temperature is around a cool 60 degrees F. If the water is too warm, the old emulsion will wash off."

Sounds like it's worth a try!

Colin Kaminski · Post by **Colin Kaminski** » Tue May 13, 2008 3:17 am

I always do a water soak or a TEA soak before exposure to shorten the exposure time.

Colin Kaminski · Post by **Colin Kaminski** » Tue May 13, 2008 3:22 am

I always do a distilled water soak or a TEA soak before exposure to shorten the exposure time.

Colin Kaminski · Post by **Colin Kaminski** » Tue May 13, 2008 3:27 am

I always do a distilled water soak or a TEA soak before exposure to shorten the exposure time.

Diode Holographer · Post by **Diode Holographer** » Tue Jul 15, 2008 3:31 am

This may not be the kind of answer you want to hear, but in my most recent shots I learned what an incredible defference the beam ratios can make. I'm sure you can get much brighter holograms if you were to use a multi-beam set-up instead of a single beam. Its not as much harder than a single beam as I have heard others imply in the past and you probably won't need a whole lot of extra complicated equipment either. A small first surface mirror or two and perhaps a plate holder may be all the additional equipment you need to pull off a multi-beam arrangment. Then again I also recently learned that my coherence length is much longer than I had originally thought which leaves me with a lot of room to play with my beam arrangment.

Colin Kaminski · Post by **Colin Kaminski** » Tue Jul 15, 2008 4:25 am

The hard part of splitbeam setups is getting the optics stable. If you have a great table it is no problem at all.

Diode Holographer · Post by **Diode Holographer** » Tue Jul 15, 2008 4:33 am

Oh, right.

I keep forgeting how blessed I am to be working out in the country where vibrations are practically non-existant. I remember when I first started, such a big deal was made about the problems of vibrations that I went to great lengths to try and limit them. Then after a few shots I started taking fewer and fewer precautions until now I use nothing but a few neoprene (sp?) pads to isolate vibration.