Multiplex with analog transparency slides ?

Holography related topics.
pierro787
Posts: 12
Joined: Tue Aug 22, 2017 5:47 am

Multiplex with analog transparency slides ?

Post by pierro787 »

Hi !

By reading messages here, I see most of you use DLP or LCD projector / panel to create multiplex hologram. This ask to buy a compatible DLP projector with a low resolution. Something that will work with a laser as illumination light is not easy to find and costs several hundred of dollars with no guarantee it will work

Why don't use analogue transparency slides ? It's possible to display static pictures on a UHD 4K screen, take picture one by one with argentic camera on B&W slides film, and project them later with the laser beam (HeNe or other) as illumination light on an old transparency slides projector with light removed (much easier to modify than a DLP projector). The different pictures can be displayed on a special screen (acrylic frosted sheet) easily this way with the help of some acrylic glycerol cylindric lenses. This way, it should be possible to get 1mm width pictures on the holographic plate. (model of the acrylic / glycerol lenses in the book Practical Holography, 4th edition)

Slides films are still available on the web for sell, they cost around 8 USD for 36 pictures, so, with 2 or 3 films, it should be OK. (around 108 pictures) It's possible to send them directly by post office for chemical processing for people who don't want do that in the lab.

There is the question of the moving slit, I know the old fashion is to use a typewriter but a dualphase stepper motor could do the job with a few programmation and soldering. (or even simpler with a motorized slider camera on a rail with a step pre-programmed).

What do you think ?

Pierre
HoloM
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Joined: Wed Jan 07, 2015 4:53 pm

Re: Multiplex with analog transparency slides ?

Post by HoloM »

Hm , i think it will work because that's the way they did it in the eighties .
lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Multiplex with analog transparency slides ?

Post by lobaz »

It can be done, of course. If you do not mind that it takes time to make the transparencies, that it is difficult to register all of them precisely, and so on. If you want to make a single holographic stereogram (multiplex hologram) just for fun, it is probably the easiest to print your images and use them as "objects" in a classical H1 transmission setup. Once you start thinking about making some device that helps you make many stereograms, modifying a DLP/LCD is a way to go.
pierro787
Posts: 12
Joined: Tue Aug 22, 2017 5:47 am

Re: Multiplex with analog transparency slides ?

Post by pierro787 »

Thanks for your informations.

What is the minimal size for a multiplex Hologram to work correctly ? I have read on the web 8" x 10 ", this is quite large.

What is the minimal power for the laser for this ? 20 mw ?

Is it then possible to convert the multiplex H1 into an embossed hologram by using a photoresist Plate and a 405 nm laser ? I remember It is necessary to spray silver on the plate before the nickel shim creation.

Pierre
lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Multiplex with analog transparency slides ?

Post by lobaz »

There in no restriction on hologram size. For example, many embossed security holograms are in fact "multiplex holograms" - and they can be just a few millimeters.

If you want to make the hologram in silver halide, there is no strict limit on laser power, in theory you can work with 1 mW. On the other hand, small power leads to long exposure times, which lead to stability problems. For practical purposes, I would use 20 mW for holograms no bigger than 4x5". Try to keep exposure times just a few seconds.

Yes, shims are usually done with a short wavelength laser and a photoresist plate. While making a silver halide stereogram is a nice exercise accessible to slightly advanced beginners, shim preparation for embossing should be done by an experienced holographer.

Petr
pierro787
Posts: 12
Joined: Tue Aug 22, 2017 5:47 am

Re: Multiplex with analog transparency slides ?

Post by pierro787 »

Thanks lobaz !

I think to start with "more classical" rainbow holograms with 3D printed objects as objects (I'm a 3D modeler, teacher and designer). By the way, I plan to create plates holders and lenses / mirrors holders on Rhinoceros software for 3D printing in ABS.

I will share the 3D STL files with the community once they have been created. I plan to start with 4"X5" silver plates.

Do you use a stabilized sandbox for holography ?

The specific moving slit for multiplex asks much more preparation in electronic and soldering than just rainbow hologram.

Pierre
lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Multiplex with analog transparency slides ?

Post by lobaz »

You are welcome, Pierre.

No, I usually use an optical table with a breadboard on the top, but I rarely make classical holograms. I am not sure what precision are you able to achieve with a sandbox - while sandbox is definitely good for classical holograms, I am not sure if it is good for a setup that requires precise alignment. Anyway, a rainbow hologram should be OK.

Do you have any prior experience with holography? If you are a beginner, you should start with simple single beam Denisyuk holograms to see if laser and chemistry are OK. Then you should build an Michelson interferometer to check stability. Then you should try a simple transmission hologram with amplitude division (light from a spatial filter illuminates both an object and a mirror that makes a reference wave), because it is not as sensitive as a true split-beam transmission hologram setup. If everything works well, you can proceed to the split-beam setup. Then you can try a full-parallax transfer (H2) hologram. And then you are ready to make a true rainbow hologram.

It is not wise to try to be too fast. Usually you will end with an empty plate without any clue what went wrong.

Besides Practical holography, consider "Seven Single Beam Projects" described by Ed Wesly (http://edweslystudio.com/Pedagogy/7SBP/ ... e7SBP.html). You will find many practical tips there.

Petr
lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Multiplex with analog transparency slides ?

Post by lobaz »

By the way, you can also consider someone that can make you a hologram from computer data, such as Geola, Lightgate, Ultimate Holography, Ceres Holographics, Holoxica or Colour Holographic.
pierro787
Posts: 12
Joined: Tue Aug 22, 2017 5:47 am

Re: Multiplex with analog transparency slides ?

Post by pierro787 »

Thanks Petr,

I will follow your advices. I will start gradually, your are completely right: nothing is worse than having a blank plate because of a specific problem and not knowing what may be the problem.

I want to make hologram for more than 20 years !! Now, I have the opportunity to have different optics / laser / plates ready and I can going to reel things.

Here in France, there is nearly nothing about holography, unfortunately. We had a museum at Paris, , long years ago, in the past, but it's not more opened except for school groups I think and only with rendez-vous.
lobaz
Posts: 280
Joined: Mon Jan 12, 2015 6:08 am
Location: Pilsen, Czech Republic

Re: Multiplex with analog transparency slides ?

Post by lobaz »

I am not sure how is holography in France; classical display holography is struggling everywhere. Maybe you can contact Yves Gentet (Ultimate holography, Bordeaux), Alexandre Escarguel (CNRS / Aix-Marseille University) or Hugues Souparis (Hologram Industries / SURYS, Paris) - they might know some holographer near you. You can also try facebook forums on holography to find someone - they are
https://www.facebook.com/groups/holographyforum/
https://www.facebook.com/groups/Holography/
I know that recently Nicolas Bonneel from Université Claude Bernard Lyon got interested in holography - maybe you can share your progress.

Petr
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