Not holograms, but very pretty: http://www.bmyersphoto.com/BWXRAY/index.html
I would love to be able to achieve some of these effects in a hologram. Seeing natural forms with complicated 3D internal structure rather than surfaces only. But how?
OT: X-Ray photographs
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Sergio
OT: X-Ray photographs
Nice photos, by the way, I guess only a series of rotacional object images could provide the stereoscopy for a turn like composite holograms made of photographic X-ray images, if you have the tens of images, probably you could transfer to an image plane hologram, even at 360 deg.
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Tom B.
OT: X-Ray photographs
Yes, you could sort of fake it with multiple images - I guess I was trying to think of a way of preparing a natural semi-transparent object that would produce a hologram that would look like one of those images, only 3D - the seashells are lovely. Alternatively, I suppose I could just borrow an X-ray laser from the local secret military research station, make an X-ray hologram, and post-swell it a few hundred percent to get a visible image
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Kaveh
OT: X-Ray photographs
This reminds me of images that we made some years ago, by stacking MRI images and other 'slice' data. We called it 'volumetric multiplexing' or, in less pompous language, superimposing the slices in the same hologram. The distance of the screen from the hologram would be changed to correspond with the data. So you end up looking at all the slices at the same time.
The slices don't have to be MRI or CAT scans. You could even take a real object, keep slicing and taking a hologram. I remember some of the holograms had very similar texture to these x-rays.
The project I was working on is still being pursued by Voxel. See http://www.voxel.com/
The slices don't have to be MRI or CAT scans. You could even take a real object, keep slicing and taking a hologram. I remember some of the holograms had very similar texture to these x-rays.
The project I was working on is still being pursued by Voxel. See http://www.voxel.com/
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Sergio
OT: X-Ray photographs
What about make a hologram from acrylic block laser generated tree dimensional images? This stuff would give lovely images in space obviously without mass, the "image" is engraved into acrylic block by means of a high power laser focused in points (Thousands) I wonder is these points could not be transferred to the space, holographically, of couse.
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Tom B.
OT: X-Ray photographs
Very interesting, thanks. It looks like you get both vertical and horizontal parallax, unlike a multiplex stereogram. I would have thought you could only get away with a relatively small number of slice exposures in a single hologram before crosstalk or film saturation or whatever began to degrade the image - the first exposure fogging the film for the next one and so on ... There is a way around this ?
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Kaveh
OT: X-Ray photographs
This is a good point. In fact a very early paper by Lambertus Hesselink and others, he showed theoretically that there was a very fast fall-off of diffraction efficiency with number of exposures, particularly with amplitude (unbleached) holograms. The paper is here:
http://kaos.stanford.edu/tech_meetings.htm
But when we tried it, it was not at all as bad. I think it might be due to the volume nature of the recording material. I remember recording around 100 exposures, with a reasonable image. This is a good case where the classical theories don't really apply, as there are so many complex processes going on. It's only by looking at the experimental results that we are guided towards the real theory.
Of course you would do the original multiplexing on your H1, so the efficiency on the H2 can still be as bright as you want. But of course signal-to-noise is the problem.
There are distinct advantages in this technique. As you say, you get full parallax, and if you have done your recording properly there should be no distortion. Also, very importantly for medical applications, there has been no intervention in the data.
We did some recordings with data from confocal microscopy, which also records slices. We used only about 10 slices. Each slice looked out-of-focus with no obvious features, but the composite hologram showed a definite geometric pattern.
http://kaos.stanford.edu/tech_meetings.htm
But when we tried it, it was not at all as bad. I think it might be due to the volume nature of the recording material. I remember recording around 100 exposures, with a reasonable image. This is a good case where the classical theories don't really apply, as there are so many complex processes going on. It's only by looking at the experimental results that we are guided towards the real theory.
Of course you would do the original multiplexing on your H1, so the efficiency on the H2 can still be as bright as you want. But of course signal-to-noise is the problem.
There are distinct advantages in this technique. As you say, you get full parallax, and if you have done your recording properly there should be no distortion. Also, very importantly for medical applications, there has been no intervention in the data.
We did some recordings with data from confocal microscopy, which also records slices. We used only about 10 slices. Each slice looked out-of-focus with no obvious features, but the composite hologram showed a definite geometric pattern.
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Tom B.
OT: X-Ray photographs
Interesting - So it IS possible to holographically record a deep stack of slices. I was thinking the only way to do this would be with a computer generated binary amplitude hologram H1 somehow converted to a reflection H2, but no doubt there are problems here too.
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Tom B.
OT: X-Ray photographs
Good suggestion - I have one of those paperweights.
The pattern itself is boring, but with some optical distortion and diffusion it might become interesting.
The pattern itself is boring, but with some optical distortion and diffusion it might become interesting.
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Kaveh
OT: X-Ray photographs
Works better than one would think. Very "low-tech" too. If anyone has access to holographic equipment, they should try it.