Making Holographic collimators
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ErichRose
Making Holographic collimators
Since I sort of prompted this thread, by describing very briefly something that Rudie Berkout had created for his lab years ago (1988?), I am going to weigh in again. Time has probably fogged my memory but what I believe Rudie created was something he used to illuminate (object beam?) his H1s when making rainbow holograms. And when making rainbows only a strip of light was needed and it played out in a single plane. Rudie used a big old 50Mw HeNe and made fairly big holograms. What he created was for a very specific set up. He often built cameras/rigs that he then used to explore various images and compositions. He was as much into the science and math as the composition and art of what he did. I have no idea at all if what he used for that camera worked easily in other set ups. I know Rudie is not as active in holography as he used to be. When I knew him he often had other projects beyond holography in the works. He wrote some papers years back. Maybe there are details there or someone who has contact with him could pick his brains?
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Ed Wesly
Making Holographic collimators
I remember seeing Rudie's HOE, and it seemed to be about a meter wide and about 15 - 20 cm tall. That was 1987 or 8, so it's a pretty hazy memeory.
I kind of got the impression that it was made in sections, like a collimated beam hit it over whatever size, then the collimator was moved, but the same recording and replay SF was in place. Kind of like a step and repeat on the collimator, reference beam stationary.
Rudie was certainly magical!
The trick in designing at lest on the math part, of what John wants to do, is calculable. Maybe if I'm not doing anything over the weekend I can give it a shot. (Yeah, right! It's the final week of classes and I'm in a grading frenzy. But then again, this might make a better diversion than looking at helpless papers...) But what will turn out is that one of the beams in the recording will have to be astigmatic; horizontal and vertical divergences will be different.
A mock up of what I am trying to describe is to look back at your spatial filter (at an appropriate power level) and the bright dot of the pinole will look a certain distance away. Then put some sort of cylindrical optic in from of it, like those wide cylinders Edmund used to sell, or eyeglass lenses that correct for astigmatism. Now looking at the pinhole, you may see something that looks like a stripe or a plus sign of light. If distances are long, you could use an SLR camera to focus on the spot, and you would find a nice vertical stripe at one distance, a horizontal at another. The math trick is in calculating these distances; the practical trick is finding combinations of lenses that would provide the requisite foci.
I kind of got the impression that it was made in sections, like a collimated beam hit it over whatever size, then the collimator was moved, but the same recording and replay SF was in place. Kind of like a step and repeat on the collimator, reference beam stationary.
Rudie was certainly magical!
The trick in designing at lest on the math part, of what John wants to do, is calculable. Maybe if I'm not doing anything over the weekend I can give it a shot. (Yeah, right! It's the final week of classes and I'm in a grading frenzy. But then again, this might make a better diversion than looking at helpless papers...) But what will turn out is that one of the beams in the recording will have to be astigmatic; horizontal and vertical divergences will be different.
A mock up of what I am trying to describe is to look back at your spatial filter (at an appropriate power level) and the bright dot of the pinole will look a certain distance away. Then put some sort of cylindrical optic in from of it, like those wide cylinders Edmund used to sell, or eyeglass lenses that correct for astigmatism. Now looking at the pinhole, you may see something that looks like a stripe or a plus sign of light. If distances are long, you could use an SLR camera to focus on the spot, and you would find a nice vertical stripe at one distance, a horizontal at another. The math trick is in calculating these distances; the practical trick is finding combinations of lenses that would provide the requisite foci.
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Colin Kaminski
Making Holographic collimators
But if I am making single set up to do say transfers and the geometry will never change I can do this with no abberations if I make the HOE right to begin with right?