One step transmission holography with lens

This is a forum to share experiences and ideas about holography.
Locked
Holox

One step transmission holography with lens

Post by Holox » Thu Sep 23, 2010 9:15 am

Hey,

I would like to do 1 step transmission hologram with lens (to get rid of making both H1 and H2 holograms). In all of the papers what I have seen the object image is really close to hologram film plane. I would like to do transmission hologram where the image is about 30 cm out of the hologram plane when illuminated with laser from back.

Does anyone know if this is possible using lenses? How should I do the setup?

Thanks!!

jnhong

One step transmission holography with lens

Post by jnhong » Thu Sep 23, 2010 7:49 pm

There are two ways to do this:

a) Instead of a lens, use a huge spherical concave mirror. The diameter of the mirror should be at least 3X the width of your plate. To minimize distortion you will want a diameter:focal length ratio of 1:4 (sometimes called F/4 or F4). Place the object at +2F.

b) Use a plaster cast to reverse your object, then shoot with a perfectly collimated reference beam. After development, reconstruct with the same reference but flip the plate around. It's called a conjugate reconstruction.

BobH

One step transmission holography with lens

Post by BobH » Sat Sep 25, 2010 12:55 am

Look for the geometry called "Open Aperture Transmission" hologram or "Achromatic Transmission" hologram. If you can live with a very small viewing zone for the image, all you'll need is a huge table, a big fast imaging lens and lots of laser light. As the viewing zone gets bigger, the size of the table, laser, and especially the imaging lens get outrageous. That's why making a "master" hologram (H1) is such a great idea! You might consider a huge Fresnel lens for the imaging lens. Ron Olson had some good luck with one of those.

Holox

One step transmission holography with lens

Post by Holox » Thu Sep 30, 2010 9:27 am

Thank you for help BobH and jnhong

"a) Instead of a lens, use a huge spherical concave mirror. The diameter of the mirror should be at least 3X the width of your plate. To minimize distortion you will want a diameter:focal length ratio of 1:4 (sometimes called F/4 or F4). Place the object at +2F."

This sounds interesting. Can you also suggest how to place hologram film and arrange lighting?

"b) Use a plaster cast to reverse your object, then shoot with a perfectly collimated reference beam. After development, reconstruct with the same reference but flip the plate around. It's called a conjugate reconstruction.[/quote]"

As far as I understand in conjugate reconstruction the hologram is not moving naturally as you move around it and is the reason for making both H1 and H2. That's why I would like not to use conjugate reconstruction.

"Look for the geometry called "Open Aperture Transmission" hologram or "Achromatic Transmission" hologram. If you can live with a very small viewing zone for the image, all you'll need is a huge table, a big fast imaging lens and lots of laser light. As the viewing zone gets bigger, the size of the table, laser, and especially the imaging lens get outrageous. That's why making a "master" hologram (H1) is such a great idea! You might consider a huge Fresnel lens for the imaging lens. Ron Olson had some good luck with one of those."

I have seen "Open aperture transmission" setups. It seems to me that then you need to record to object(image) close to hologram film. I would like to get good viewing zone as well.

BobH

One step transmission holography with lens

Post by BobH » Thu Sep 30, 2010 2:37 pm

Holox wrote: I have seen "Open aperture transmission" setups. It seems to me that then you need to record to object(image) close to hologram film. I would like to get good viewing zone as well.
Not necessarily. Good viewing zone, object far from plate, single step transmission hologram; looks like you're in for a VERY expensive hobby! Sell the Ferrari. Or consider a computer assisted system like those used by Zebra Imaging, Geola or RabbitHoles.

Colin Kaminski

One step transmission holography with lens

Post by Colin Kaminski » Fri Oct 01, 2010 12:53 am

Couldn't you do this with a 30" spherical mirror and very few other optics? Woops, I forgot about the large field of view. So a 1.5 meter spherical mirror? :drool:

JohnFP

One step transmission holography with lens

Post by JohnFP » Tue Oct 19, 2010 11:39 am

If your eyes are close to the plate then you will also have a large viewing zone. And for transmission this works out fine as you can get close to look in the hologram and are not obstructing the reconstruction light. My favorite thing to do with any transmission hologram is to illuminate it with the laser and get as close as I can to look "in" the window as you can see every single detail, not only on the object(s) being hologram but any reflections or holograms of mounts, bases, tables blockers, etc. Just insure you dont get to close with relation to the reconstruction light and its angle as to blind yourself.

Locked