I GOT IT!!!
The image I've been projecting for over a year now is apparantly the wrong image. Going back through all these post and trying every bodies suggestions over and over again I managed to find the true real image.
I'll set-up tonight and shoot. I'll let you all know how it goes. Thanks for all the help thus far, but don't be surprised if I have more questions tonight or tomorrow.
[EDIT] I just noticed the image I'm getting is upside-down. Is that proper?
H2 Copy: Integraf's Suggestion and Yours
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Justin W
H2 Copy: Integraf's Suggestion and Yours
Howdy DH!
Yeahman - sounds like you were possibly looking at some of the whatever-order diffracted images....
Regarding your edit: Yessir indeedy that is correct - the projected real image will appear upside down... and I bet you also find some oddness in how your reflection H2 replays. You'll find the image to reconstruct with your replay beam falling on the opposite side than you might think. I had to reshoot my frst couple reflection H2's - I thought I had confused my substrate and emulsion side in the dark
Nope... It just turns out they replay from the other side. And I was so used to making reflection grams with the emulsion toward the object.. Nope. If you plan to blacken your emulsion side of your final hologram, make sure you place your H2 plate with the emulsion facing the reference beam
Yeahman - sounds like you were possibly looking at some of the whatever-order diffracted images....
Regarding your edit: Yessir indeedy that is correct - the projected real image will appear upside down... and I bet you also find some oddness in how your reflection H2 replays. You'll find the image to reconstruct with your replay beam falling on the opposite side than you might think. I had to reshoot my frst couple reflection H2's - I thought I had confused my substrate and emulsion side in the dark
Nope... It just turns out they replay from the other side. And I was so used to making reflection grams with the emulsion toward the object.. Nope. If you plan to blacken your emulsion side of your final hologram, make sure you place your H2 plate with the emulsion facing the reference beam
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Ed Wesly
H2 Copy: Integraf's Suggestion and Yours
This setup makes a transmission hologram. Ref and obj are coming from same side of the plate.
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Diode Holographer
H2 Copy: Integraf's Suggestion and Yours
Alright, gentlemen. First let me apologize for the delay in response. I forgot last weekend was going to be Easter, but besides that it was a little cold here last weekend and my "lab" isn't heated (or rather I can't heat it effectively let alone efficiently so unless I have to I don't); so I decided to postpone. Next let me thank everyone who has chimed in to help me figure this out.
Ed, Bob, between the two of you I believe I have "properly" identified the different images. Unfortunately, as I feared, the hologram copy attempt seems to have failed. Justin, thanks for the tip on viewing the copy. I'm checking it over and over from ever possible orientation and won't give up on it soon.
I realize it might help if you guys know more about my set-up. I can start by saying that vibration is absolutely not an issue for me. I can go into more detail on this if you like, but I think you can trust me on this one. All my "mounts" are random stuff I have on hand that will do the job. Most of them suggestions from Integraf. Laser is mounted on a clothes pin stuck in a cup of salt, binder clips and book ends are supporting my plates/film holder and wood blocks, bricks, ect let me vary the relative height of my film and scene. I do have a few other small components. Lenses, a couple small mirrors (plan on getting bigger and better ones soon), some glass plates, etc. I haven't introduced any of them yet, because there has been no need to. It may be an incredibly simple system, but it has produced around a dozen holograms.
I shine a raw laser beam through the plate at the same angle and side of the hologram (emulsion) as when it was first shot. I (on the substrate side of the plate) look through the hologram and see the original scene (a face). This is the virtual image.
Now with out moving anything else (including my head/eye) I spin the hologram 180 degrees about a vertical axis (emulsion now facing me, substrate facing the laser) and I can see the "face", BUT it's clarity depends upon the distance of my eye to the plate and the image is upside down. I move nothing else, but replace my eye with a white card and I can see the "face" right side up and in good focus projected onto the card. This is the real image.
Is all of this correct?
I believe it is so I'll continue, but please correct anything I have wrong here.
Now again I change nothing else, but I introduce a double concave lens between the laser and the hologram so that it diverges the beam only a little. The real image is still there, but a little fuzz. I move the white card toward and away from the plate and I get the response you mention above, Bob. At a given distance the nose comes into focus and as I move the card away the nose goes out of focus and deeper parts of the face come into focus the farther I move the card.
A 3 dimensional image focused "3 dimensionally" into 3 dimensional space... crazy.
Now I change nothing else, but I swap the lens out for ones with shorter and shorter focal lengths (diverging the beam more and more). The more the beam diverges, the further away from the plate the image is focused. And I think this is my trouble. The beam I'm trying (want) to use is rapidly diverging. As it was when it made the hologram. Bob, I think you may have told me that here, but I really didn't follow you.
A converging reconstruction beam "matches" a diverging reference beam? Does that mean I need a rapidly converging reconstruction beam for my H1 in order to get best results?
Well, since I don't think I can match the original reference beam to get best results, is there anything I can do to get any results.
These questions are directed at everyone. I quote Bob a lot because he's said a lot.
Thanks to everyone for your help. It is much appreciated.
Ed, Bob, between the two of you I believe I have "properly" identified the different images. Unfortunately, as I feared, the hologram copy attempt seems to have failed. Justin, thanks for the tip on viewing the copy. I'm checking it over and over from ever possible orientation and won't give up on it soon.
I realize it might help if you guys know more about my set-up. I can start by saying that vibration is absolutely not an issue for me. I can go into more detail on this if you like, but I think you can trust me on this one. All my "mounts" are random stuff I have on hand that will do the job. Most of them suggestions from Integraf. Laser is mounted on a clothes pin stuck in a cup of salt, binder clips and book ends are supporting my plates/film holder and wood blocks, bricks, ect let me vary the relative height of my film and scene. I do have a few other small components. Lenses, a couple small mirrors (plan on getting bigger and better ones soon), some glass plates, etc. I haven't introduced any of them yet, because there has been no need to. It may be an incredibly simple system, but it has produced around a dozen holograms.
I believe I now fully understand you and I think I have all this going on as you state, but let me go over it again because I think it may be my problem.BobH wrote:Let's say the image is a human head looking toward the H1. When you project the real image with an undiverged raw laser beam, you see a sharp image of the face on a card. AS the card is moved closer to the H1, the face image gets smaller. As the card is moved away from the H1, the face image gets bigger. With an undiverged raw beam on the H1, there is always a sharp image of the face on the card regardless of its distance from the H1.
Now illuminate the H1 with a beam diverging from a point a long way away (that is, as collimated as you can make it). Start by placing the white card very close to the H1. You should see a blob of light. As you move the card away from the H1, eventually you'll see the tip of the nose come into focus. As you continue to move the card away from the H1, the cheeks will come into focus on the card and the tip of the nose will blur out. Continue to move the card back and the eyes, then the ears will focus as you pass them but the rest of the three dimensional image will blurr out because it's focused at different locations in space.
I shine a raw laser beam through the plate at the same angle and side of the hologram (emulsion) as when it was first shot. I (on the substrate side of the plate) look through the hologram and see the original scene (a face). This is the virtual image.
Now with out moving anything else (including my head/eye) I spin the hologram 180 degrees about a vertical axis (emulsion now facing me, substrate facing the laser) and I can see the "face", BUT it's clarity depends upon the distance of my eye to the plate and the image is upside down. I move nothing else, but replace my eye with a white card and I can see the "face" right side up and in good focus projected onto the card. This is the real image.
Is all of this correct?
I believe it is so I'll continue, but please correct anything I have wrong here.
Now again I change nothing else, but I introduce a double concave lens between the laser and the hologram so that it diverges the beam only a little. The real image is still there, but a little fuzz. I move the white card toward and away from the plate and I get the response you mention above, Bob. At a given distance the nose comes into focus and as I move the card away the nose goes out of focus and deeper parts of the face come into focus the farther I move the card.
A 3 dimensional image focused "3 dimensionally" into 3 dimensional space... crazy.
Now I change nothing else, but I swap the lens out for ones with shorter and shorter focal lengths (diverging the beam more and more). The more the beam diverges, the further away from the plate the image is focused. And I think this is my trouble. The beam I'm trying (want) to use is rapidly diverging. As it was when it made the hologram. Bob, I think you may have told me that here, but I really didn't follow you.
Yes, my set up for shooting an H2 is exactly like the drawing. I'm attempting to use the exact same, rapidly diverging, bare diode beam to project the H1 image as was used to record it.BobH wrote:If your set-up is anything like the drawing, the real image will be terribly distorted. It's because the reference beam is diverging rapidly when you make the H1. If you then rotate the plate 180 degrees to see the real image, the reconstruction beam is then also diverging (instead of converging, which would match the reference beam used for recording it). That's why people use collimated beams for whenever they plan on reconstructing a real image. You want to always match the reconstruction beam to the recording reference beam geometry as well as you can for best results.
A converging reconstruction beam "matches" a diverging reference beam? Does that mean I need a rapidly converging reconstruction beam for my H1 in order to get best results?
Well, since I don't think I can match the original reference beam to get best results, is there anything I can do to get any results.
These questions are directed at everyone. I quote Bob a lot because he's said a lot.
Thanks to everyone for your help. It is much appreciated.
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Kaveh
H2 Copy: Integraf's Suggestion and Yours
I think all you say is correct. Perhaps I can illustrate how I understand the procedure, with a few diagrams.
I have drawn out the standard method of recording and reconstructing an image using collimated beams in both cases.
First image on the left shows the observer looking through the hologram and seeing the virtual image. We assume the geometry of the recording and reconstruction are identical. The image is seen perfectly and without distortion.
On the right, we have used the conjugate of that collimated beam, i.e. every ray is reversed in direction. (Please note that contrary to most people, I find it conceptually simpler to keep the hologram in the original place and illuminate from the other side. This makes is simpler to think about how the light diffracts, and hence where the image goes. In the lab you would just flip the hologram through 180°.)
With the conjugate reconstruction beam, all rays are simply reversed, so the rays will now focus onto a real image, identical to the original image, and undistorted, but pseudoscopic, so you view the inside of the jug. You will notice I have put the observer upside down in this case, because if you flip the hologram in the lab, you will see the real image upside down. Again, for me this makes it all clearer.
Now let's record and reconstruct the image, this time using a diverging beam:
The recording and reconstruction beams are identical, so the image is again undistorted. How do we get the undistorted real image? Well, we need the conjugate of the recording beam, which now is a converging beam. All rays are reversed, and again the real image is seen undistorted but pseudoscopic.
Finally, let's see what happens when we use not the conjugate beam, but another diverging beam to create the real image:
This is equivalent to using a diverging beam and "flipping" the hologram and using the same beam to illuminate it. A little thought about where the rays go will show you that the image is now "pushed out" and enlarged. (If you want a "back of envelope" sketch of how we can work this out, I am happy to post it.)
Now whenever the recording and reconstruction beams are not identical (in geometry or wavelength), you will get distortions and aberrations. I think I am right in saying there are no exceptions to this. So you will see the image "swing" as you move your head side to side, and you will not be able to get a sharp image of any point on a screen.
So to go back to your problem, there is only one practical solution, and that is to use a collimated beam for recording and reconstructing H1. Hope this clarifies things a bit, although what you said was spot on!
I have drawn out the standard method of recording and reconstructing an image using collimated beams in both cases.
- collimated.jpg (124.95 KiB) Viewed 4566 times
On the right, we have used the conjugate of that collimated beam, i.e. every ray is reversed in direction. (Please note that contrary to most people, I find it conceptually simpler to keep the hologram in the original place and illuminate from the other side. This makes is simpler to think about how the light diffracts, and hence where the image goes. In the lab you would just flip the hologram through 180°.)
With the conjugate reconstruction beam, all rays are simply reversed, so the rays will now focus onto a real image, identical to the original image, and undistorted, but pseudoscopic, so you view the inside of the jug. You will notice I have put the observer upside down in this case, because if you flip the hologram in the lab, you will see the real image upside down. Again, for me this makes it all clearer.
Now let's record and reconstruct the image, this time using a diverging beam:
- diverge-converge.jpg (115.81 KiB) Viewed 4563 times
Finally, let's see what happens when we use not the conjugate beam, but another diverging beam to create the real image:
- diverge-reconstruction.jpg (76.94 KiB) Viewed 4560 times
Now whenever the recording and reconstruction beams are not identical (in geometry or wavelength), you will get distortions and aberrations. I think I am right in saying there are no exceptions to this. So you will see the image "swing" as you move your head side to side, and you will not be able to get a sharp image of any point on a screen.
So to go back to your problem, there is only one practical solution, and that is to use a collimated beam for recording and reconstructing H1. Hope this clarifies things a bit, although what you said was spot on!
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Diode Holographer
H2 Copy: Integraf's Suggestion and Yours
Thank you, Kaveh. That was very helpful. Now I understand how/why a Converging Reconstruction beam "matches" a Diverging Recording beam.
So basically I'm boned? I'm a little miffed that Integraf would detail a project that cannot be done, but I can't say I'm very surprised.
I have one more idea. While not ideal results obviously, does anyone/everyone think this set up will at least produce a viewable H2?
So basically I'm boned? I'm a little miffed that Integraf would detail a project that cannot be done, but I can't say I'm very surprised.
I have one more idea. While not ideal results obviously, does anyone/everyone think this set up will at least produce a viewable H2?
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BobH
H2 Copy: Integraf's Suggestion and Yours
That should work better than no lens at all. You can also move the laser as far away as possible to reduce the distortions to a minimum. But if you have a lens large enough to cover the H1, why not use it to make a collimated reference beam when making the H1? Then, use it to collimate the reconstruction beam for the H1 and you're all set. You may still be able to use light that goes around the lens as a reference for the H2.
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Diode Holographer
H2 Copy: Integraf's Suggestion and Yours
I'll try that when I get more film, but right now I don't want to take the chance of the H1 not coming out. I only have three attempts left on me, so I'll stick with this for now (since I'm already in a hole) and I'll try collimating the reference beam on the H1 recording later.
By the way that's another first I've had since talking you all. I've managed to project an image onto a screen while illuminating the whole plate. All I need was a drastically converging reconstruction beam.
By the way that's another first I've had since talking you all. I've managed to project an image onto a screen while illuminating the whole plate. All I need was a drastically converging reconstruction beam.
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Kaveh
H2 Copy: Integraf's Suggestion and Yours
When projecting the image, try and get it as sharp as possible. As you move the screen, different points should come into perfect focus. Pick out a highlight spot or a recognizable point and see if it focuses to a perfect point on the screen. Then you know you have your conjugate beam right, and your final hologram will then be free of aberrations, i.e. image swinging as you move your head.
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Diode Holographer
H2 Copy: Integraf's Suggestion and Yours
Alright, gentlemen.
I attempted the set up I illustrated above. However, my original reference beam was diverging to such a great degree that it took two lenses just to get the reconstructing beam even close to the right converging degree. Also, by the time it was even close everything was so far away from the laser I don't think the reference beam would have been bright enough. So I decided to scrap that idea and just start over like Bob suggested.
As I thought it took a few shots to get it right (beam ratios), but I did get it and I have once again broke my personal bests (brightness/sharpness, depth, viewing angle). I also got a real nice shot of the lens and lens holder. Which is something I wasn't expecting. If the light passing through the lens was the reference beam for my object? Where did the lens' light get it's reference beam?
I cut my last piece of film in half to stretch out my supply a bit more and I used the extra piece to try the set up above for shooting an H2. It didn't come out, but the set up is looking good. I can project the real image while illuminating the entire hologram. I'm not yet certain why the first try didn't work, but if I had to guess I would say beam ratios. It will be a week or two before I order more film, but when it gets here I will pick this up right here where I left off.
Thanks again for everyone's help and suggestions. I'll be sure to keep you posted. In the mean time are there any other ideas, suggestions or general thoughts that anyone would like to add?
Cheers
I attempted the set up I illustrated above. However, my original reference beam was diverging to such a great degree that it took two lenses just to get the reconstructing beam even close to the right converging degree. Also, by the time it was even close everything was so far away from the laser I don't think the reference beam would have been bright enough. So I decided to scrap that idea and just start over like Bob suggested.
As I thought it took a few shots to get it right (beam ratios), but I did get it and I have once again broke my personal bests (brightness/sharpness, depth, viewing angle). I also got a real nice shot of the lens and lens holder. Which is something I wasn't expecting. If the light passing through the lens was the reference beam for my object? Where did the lens' light get it's reference beam?
I cut my last piece of film in half to stretch out my supply a bit more and I used the extra piece to try the set up above for shooting an H2. It didn't come out, but the set up is looking good. I can project the real image while illuminating the entire hologram. I'm not yet certain why the first try didn't work, but if I had to guess I would say beam ratios. It will be a week or two before I order more film, but when it gets here I will pick this up right here where I left off.
Thanks again for everyone's help and suggestions. I'll be sure to keep you posted. In the mean time are there any other ideas, suggestions or general thoughts that anyone would like to add?
Cheers