Cameras for Computer Generated Holograms (CGH)

[xavislow]

Hey folks!

My name is Xavier and I'm a PhD student. My project is scoped in the Nanophotonics field, but I need to make some holograms in order to be able to do my experiments.
My advisor and I, we already have the software to generate the holograms, and we also know the process to make these holograms. However, in order to make them, we need a camera, and here's the problem. We do not really know which camera we should buy. My advisor worked with someone before who used a MINOLTA SRT 101 along with a Gigabitfilm of high quality and it worked out pretty well. So we know that this combination works, but we wonder if maybe buying a better manual camera or another kind of film we could get better efficiency on our holograms.

By the way, we are going to use light from 300 nm to 1000nm.

Heaps of thanks in advance!

[xavislow]

Oh, and I also have another inquiry. The method we use to make the holograms is what follows. Using a Matlab code we generate a interference pattern and we print it with a high resolution printer. Then, we take a picture of this pattern with a camera (that was the reason why I posted this message) and finally we reveal it.

Do you know a better method to generate Holograms digitally?

Thanks again!

[rzeheb]

Hi Xavier and welcome to the forum. I assume you want to take the high-resolution photograph of your digitally generated interference pattern so that you can have something (the developed film) to pass light through? If so, would it be possible to use a high resolution printer to print the interference pattern directly onto transparency film and avoid the photography altogether? I say this not knowing if I understand your goals correctly or if sufficiently high resolution printers are available to you compared with the cost of film and camera.

[a_k]

I guess the idea is to increase the resolution per area unit by a massive size reduction. This way the resolution of the printer is not the limiting factor. The higher the size ratio original:recording, the higher is the resolution achieved. The medium used for the recording must of course support the resolution achieved.

[Ed Wesly]

And the lens, also! The benchmark for consumer cameras is at about 100 lp/mm attained by some 50 mm Nikon and Canon lenses for SLR's . Some process camera lenses can attain better than that. And don't forget that the resolution of an optical system is 1/lens resolving power + 1/film resolving power = 1/ system resolving power.

The earliest publication of this idea, generating interference fringe patterns and minifying them via photography, that I have found, is in R. W. Wood's Physical Optics of 1905. There is a Fresnel Zone Plate pattern that you could photograph and reduce and use!

There may be earlier incarnations of this concept, but I like to give him credit since I am a fan of this cat, as he invented his own diffraction color photo process whose descendant is the holographic 2-D sticker, was a pioneer of IR and UV photography, came up with frosting the inside of light bulbs by swizzling a little hydrofluoric acid in them, debunked the N-Rays, devised the spinning mercury mirror (so he could see the canali on Mars, created the first fisheye camera by filling pinhole camera with water, etc. His first published scientific paper was called something like "In the Realm of the Dream; The Secrets of Hasheesh". What's not to like?

[xavislow]

Hey thanks for the replies!

@rzeheb: I'm just starting my PhD, so I do not know a lot about these things. But I think that what a_k said it's exactly what my advisor told me. I think that we take a picture of the printed interference pattern so that the printer will not be the limiting factor. And he also told me that we need to take a picture with a manual camera (and not a digital one) because using a high resolution film you can reach a better quality in your holograms. Oh, and yes, the developed film is what we'll use to make the light pass through.

So...do you guys know about a good manual camera? Maybe a Canon or a Nikon? Is it Minolta alright?

Thanks again!!

[Jeffrey Weil]

Ed W is correct, it's about the lens not the camera. Any camera will do fine, what you need is a good lens with great flat field response if you want the largest active area possible on the film. If you want to save money get a decent enlarger lens and fit it to a camera body.

Jeffrey Weil
NorthBeach Holography Inc.

[xavislow]

Thanks again!

So...any recommendation for the lens? We will use a Gigabitfilm. In its pamphlet it says:

'You should try not to stop your lens down beyond f/5.6 getting the maximum of resolution. If you need depth of focus, you must stop down further. Many camera lenses are still designed to give better contrast, this could reduce considerably resolution.'

I'm sorry, I just don't know anything about cameras and lenses and I have been looking up some information and it's a gibberish...there are 8234924 cameras and lenses and I do not know which one we should buy. We have a good budged, that means that we could buy a really good lens. Of course, we don't want to a waste money buying the best lens ever if a much simpler one could do the same job.

I'd be glad if you could be specific in your recommendations. Obviously I am just looking for a recommendation, in case I bought something and I didn't like it would be my fault, I would not blame anyone, you are here just to help!

Hey, thanks you a lot!!!

Xavier

[Jeffrey Weil]

Ed W gave you some numbers of what a named brand lens could do. You know your target that's being shot, and what size you want the features in your final piece of film. Does the math work out?

But even better than that is just giving it a go! Ask your friends and family if you can borrow whatever film camera they have lying around. since the world has gone digital this stuff is in everyones closet just waiting for you to turn it into something amazing for free. You have nothing to lose.

Plus even if you fail you'll still learn something and that'll make you successful on your next attempt.

In holography you'll find plenty of ways to spend your money, do whatever you can for free.

Good, fast and cheap. You can usually have any two. With a borrowed camera you'll be getting fast and cheap at a minimum. If it turns out to be good you get all three. That's very rare, take advantage of it.

Jeffrey Weil
NorthBeach Holography Inc.

[xavislow]

Thanks for the piece of advice Jeffrey!

And thanks to the others as well!