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This is a short tutorial about why a transmission hologram recorded in a wet emulsion might not be viewable when dry. It is a response to a question by Justin W on the Holography Forum.
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Absolutely super presentation, Kaveh!
Thank you Kaveh, a great presentation.
Great explanation! I think Steve Benton was a fan of an offset object in order to have the fringes more perpendicular in the emulsion, thus reducing the side effects of emulsion shrinkage on the fringes. Even dry/wet/dry processing (silver halide gelatin emulsions) allegedly causes some emulsion shrinkage changing the fringe angle & affecting efficiency and accurate pseudocolor recording at the desired viewing angle/distance.
Now that you’ve teased us with this short presentation, when can we expect more detail including reflection/volume holos and maybe some simple equations and recommendations?
Thank you!
I am flattered that someone as knowledgeable as yourself is suggesting I do more of these! Your wish is my command, Jody. I would really like to do more of these. I feel it’s my duty to pass on whatever I have learned to the next generation of hologrphers…
Everyone in the field would benefit from your clear explanations including me. You’ve forgotten more about holography than I ever learned! I look forward to more!
One way to get a larger beam angle inside the emulsion would be to contact a prism against it and illuminate through that – need a collimated reference beam though.
But I’m not sure that helps much as you just end up messing about with matching fluids at replay time instead of recording time…
oops – I didn’t see you’d already suggested this on the other forum – didn’t realise there were two pages, duh.
I’ve found an ancient sketch of something similar I did years ago at
http://people.brunel.ac.uk/~eesrjjn/masstran/cdg/masstind.html
It was easier to contact the prism semi-permanently to a thin sheet
of glass (with something like Canada balsam) and mount that, rather
than trying to work with a discrete prism.
That is indeed interesting Kaveh. So would shooting the plate with just the right amount of preswelling using a specific water/alcohol mix, then allow with the dried plate a good edge-lit replay hologram?