one step rainbow holograms NICE!

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zipsister

one step rainbow holograms NICE!

Post by zipsister »

Hi All,
I made one step rainbow and one step reflection holograms (both split beam) back in the 1980's. You use a large lens between the object and the hologram; the lens is used to focus the image of the object at the plane of the hologram (similar to the master hologram in a normal H1-H2 set-up) with the reference coming in at the side as per normal. A limiting factor is the left-right parallax dictated by the lens size. My lenses were about 10 cm in diameter. An excellent alternative that I've used since is a flat fresnel lens from an old over head projector. The one I used was about 30cm square. Using one of these only requires about 60 cm between the object and the hologram with the fresnel lens in the middle; they have lovely short focal lengths. The image depth/brightness obtained by the one step method is on a par with the two step method.
zipsister
zipsister

one step rainbow holograms NICE!

Post by zipsister »

Forgot to add...with my one step rainbow/reflections I also used black cardboard on the object side of the lens/fresnel lens with a 0.5cm slit (top-bottom, as specified by Hariharan) with the reference beam coming in from the side. This gave the generous depth.
zipsister
JohnFP

one step rainbow holograms NICE!

Post by JohnFP »

How about a single beam, image planed, one step rainbow?
http://www.holograms3d.com/Illustration ... RnbEdW.JPG
Colin Kaminski

one step rainbow holograms NICE!

Post by Colin Kaminski »

Make sure to have a long coherenct laser before you try than one. :wink:
JohnFP

one step rainbow holograms NICE!

Post by JohnFP »

Yes Colin, having power and long coherence does lend itself to more novel configurations. Here are some more fun ones. I have used all of these. Now I need to come up with and H1 to H2(refl) that does not need a vibration isolation table. :wink:

(side view)
This is a set up for using a singel beam to create the H1 master and H2 copy. Just block off parts of the beam you don't need. It is a little restrictive on light ration but I have used this config and it does work. Might be a good system for a school in which they just want to demonstrate the priciple and get a hologram.
http://www.holograms3d.com/Illustration ... litter.jpg

(ovehead view)
H1 to H2 - The variable Beam Splitter can also be a simply rotary attenuator.
http://www.holograms3d.com/Illustrations/H2SetUp.jpg

(overhead view)
Same as above but beam paths are matched.
http://www.holograms3d.com/Illustration ... erence.jpg

(overhead view)
Coherence not and issue. Here you set up the complete geometry and block off the illumination of the small H2 plate for creation of the transmission H1 (large plate). Then flip the H1 master around, drop out the first beam splitter and unblock the reference for the small H2 for creation of the final H2 reflection hologram.
http://www.holograms3d.com/Illustrations/H2SetUpWH1.jpg

(side veiw)
This uses a technique of adding additional lighting for an object right through the plate. I have heard that this does not work with Silver, but I have one additional source that says it does help with DCG. I have also found you can move the center of the beam and alter ratios to some degree.
http://www.holograms3d.com/Illustration ... nisyuk.jpg
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