My first H1-H2, rising some questions

[Pianomaxx]

Hello Holographers!



I am really happy that I successfully recorded a really bright transmission-holo on PFG-01, using the EDTA-bleach, with a single beam setup. It's a LEGO-man, standing next to a small and a big silver ball, mirroring himself in it.

The transmission-holo:





I could catch the reconstructed image on cardboard, so I tried a copy on H2, also single beam setup. Exposure 20sec with 6mw HeNe on PFG-01, processing Dokumol and KDi-Bleach.

I had problems with TEA (streaks, drying difficult), therefore I chose Pyrochome processing for the desired color shift.



View 1 (sorry for the dirty processing, looks as if my lab is too dusty, but I think you can guess something)





View 2





So, after the first enthusiasm that gave rise to some questions: Why can I see 3 different colours? I looks almost like green, yellow and red together. And I didnt record a rainbow hologram, at least not intentionally.

In reality, the trousers of the LEGO-man were red, and his shirt striped black-and-white. Now I got green and yellow! The botton is highly reflecting and got red.



The most important issue is, that the viewing angle is very narrow. Only from one certain reconstruction angle I can see the holo, and it's very luminous. I guess it's got to do with my compact geometry, which also causes ghost images of the reference-beam mirrors. (?)



Best regards,

Max

[MichaelH]

Max, TEA usage isn't too hard once you get a grasp of the basics. Good squeegeeing is key.



http://www.dragonseye.com/blog/archives ... eeing.html



The color differences might be due to uneven exposure and subsequent shrinkage of the emulsion due to loss of silver during processing. The JD2 + EDTA process will prevent that but you'll have to use TEA or sugar if you want any color shifting.



Did you blow-dry the plate (are you using film, or plates?) after bleaching? If so, your drying needs cleaning. If not, make sure you dry the plate so that it's leaning against a clean surface, emulsion down.



The limited viewing window is due in part to the highly diverging reference/object beams and (I'm guessing) you were using a master that's no bigger than the copy.

[Pianomaxx]

Max, TEA usage isn't too hard once you get a grasp of The limited viewing window is due in part to the highly diverging reference/object beams and (I'm guessing) you were using a master that's no bigger than the copy.

Thanks, Michael, for the useful hints, I will try your squeeging method next time. There are great instructions on your website!



I read that usually a bigger master is used for H1-H2-copies. But then I would need to collimate the beam to a converging one, to focus it on the smaller H2-plate, is that right? In fact, the beams are both diverging a little, I got a lens with only f=25mm, therefore the recording setup is about 3m far from the lens.

Your explanations for the different colours seem very reasonable, because the illumation of ref and obj was indeed very uneven. Of course, due to the single-beam-setup I could adjust intensity ratios only by moving the spread beam.

[MichaelH]

I read that usually a bigger master is used for H1-H2-copies. But then I would need to collimate the beam to a converging one, to focus it on the smaller H2-plate, is that right?

If you have a collimator, you'd want to use a fully collimated beam when making the H1 and when illuminating the H1 when making the H2.



You'd ideally want a converging beam illuminating the H2 but a diverging beam works just fine for display work.

[Pianomaxx]

Hello Michael.



I understand that a slighty diverging beam is not a problem, concerning the reference beam. That is the later reconstruction beam, which is usually also diverging a bit, so there is no big distortion.



But if I use a diverging object beam for illuminating the H1, while copying on H2, I think that it is impossible to copy the complete H1 onto H2, just because H2 is smaller and the diverging beam passes the H2 partly.

So, shouldn't I achieve the widest viewing angle, if I use a converging beam matching exactly the sizes of H1 resp. H2?



By the way, I am very impressed by the viewing angle of the Saturn-Holo, which you are offering for sale. Could you please describe geometry of the setup, how it was recorded?



Best regards,

Max

[MichaelH]

Max,



You have to be careful about the terms of reference and reconstruction beams. The former is the beam used when making the hologram in question and the latter after you've exposed and developed the hologram.



If you have a a diverging H1 reference beam and a diverging reconstruction H1 beam you'll end up with an enlarged image. The amount of enlargement depends on the amount of divergence. You'll also get decreasing "window" sizes as the divergence goes up.



Collimating both reference and reconstruction beams for the H1 is the best route most of the time. There may be cases where you want a specific, unusual look or if you're doing specialize HOE work where non-collimated beams are necessary.



For display work you can get away with a diverging reference beam on the H2. Most people won't notice the type of distortion typical of diverging H2 reference beams.

By the way, I am very impressed by the viewing angle of the Saturn-Holo, which you are offering for sale. Could you please describe geometry of the setup, how it was recorded?

I wish I could. That particular hologram was made by Lon Moore. He lurks here sometimes and hopefully will have some time to fill you in on the geometry used.