Please help diagnose image issues

[Holomark]

I am working on white light image plane reflection hologram.
I have now created one, pictures of which are posted in the gallery as Cherub and Dove.
The subject was the base of a lamp which a Cherum sitting next to a plant with a dove on top of the plant.
The subject size is 7 inches tall, 4 inches wide, and 3 inches deep.
H1 was created with 4 x 5 VRP Plate and developed with JD2
H2 also used 4 x 5 VRP Plate and developed with JD2
The final hologram extends just over 1 inch in front of the plate (flowers and hand). While I am pleased that I have finally created something I can call a real hologram...

I want to improve on the H2 I created (three pictures of which are shown as pictures A1, A2, and A3 - see Cherub and dove in Gallery)
(Photographs were taken outside using only sunlight and picture taken with IPhone)
My issues:
1. The image has a blue tint - Is this due to the temperature of the developer? - too cold or too hot??
2. The viewing angle is somewhat limited. As you can see from the picture I had trouble capturing the whole hologram in one picture - Both A1 and A3 are the same plate, but viewed at slightly different angles - resulting in different portions of the hologram being viewable. The viewing angle to see all of the hologram seems too limited - you have to be in just the right angle to see all of it...I was expecting a much larger viewing angle.
3. I want to make the image brighter

Now Plate B seems brighter, but for some reason only a portion of the hologram is viewable. See 4 pictures of Plate b in Gallery. The bottom left of the hologram is simply black, but where I have an image the image is brighter. It appears that the portion of the hologram that is viewable is behind the plate while the portion that is not viewable is in front of the plate. Why would the image behind the plate develop fine, but the image in front of th plate be black. (I believe the only difference between plate A and plate B is exposure time - with Plate B exposed longer than Plate A - they were both shot in the same session)

I tried another attempt to make the image brighter - optic positions were changed a little and longer exposure times.
The shortest exposure time resulted in a hologram similar to B (but a larger black area) AND with a hologram on both sides of the plate. The "front" of the plate shows a hologram similar to plate B (only head and dove), but the BACK of the plate appears to have a hologram of Plate H1!!! Interestingly, I can see what appears to be a burnt in image? - milkiness in the shape of the subject!
Does this mean that my beams are out of balance??? Or am I simply overexposing??? or both?? or something else???

There are just so many different things I could change...I'm not sure of the logical order to proceed.
Please, any help, comments or suggestions would be helpful

[rzeheb]

Hi Holomark,

I'm just heading out the door, so my replies have to be very brief this time.

1. The image has a blue tint - Is this due to the temperature of the developer? - too cold or too hot??

This is most likely caused by shrinkage of the emulsion during bleaching and drying. If you are drying your plate with a hair dryer using hot air, try using cold air and drying a little more slowly.

2. The viewing angle is somewhat limited. As you can see from the picture I had trouble capturing the whole hologram in one picture - Both A1 and A3 are the same plate, but viewed at slightly different angles - resulting in different portions of the hologram being viewable. The viewing angle to see all of the hologram seems too limited - you have to be in just the right angle to see all of it...I was expecting a much larger viewing angle.

This is caused by the ratio of the size of your H1 transmission master to your H2 and the distance between them. To improve the viewing angle you would need to have a larger H1, the larger the better. Using a smaller object as your subject matter would also help a lot if you cannot make larger H1s.

3. I want to make the image brighter

Optimization of reference to object beam ratio, exposure time, development time...... it's the art.

Sorry I couldn't take more time to respond. You are doing fine. Keep it up. It's a learning process, but that's what makes it fun!

Ron

[Ed Wesly]

Let’s start with your last Gallery picture, C. Yes, you should see an image of the H1 when looking at the wrong or pseudoscopic side of the copy. Since you are transferring from a 4 by 5 to a 4 by 5, your viewing window will be quite small. Imagine two 4 by 5 picture frames in a row, separated by the H1-H2 distance, and the only things that can be seen have to be framed by both frames. Sometimes this is called the aperturing effect. That is why larger H1’s are used to make transfers, like 8 by 10’s to 4 by 5’s. It could be argued that this could cut down on brightness, but if you want a wider viewing zone you need larger masters.

The blue business is al in the processing, especially if you are using JD-2 it has a reversal bleach, which gives shrinkage of the emulsion to shorter wavelengths. If you use a bleach of the type called rehalogenating, you should keep the same laser replay color as recording.

If you have some of the bleach that has not been used to clear a plate yet, add potassium bromide with a concentration of 30 grams per liter to turn this dichromate-based reversal bleach into a dichromate-based rehalogenating one, and your replay color will be pretty much exact laser green.

The dark patches could be from overexposure, which with the JD-2 processing you could end up removing most if not all modulable material, and have a dead spot. If it’s in the same spot on both, it could be movement of the plate in its holder, double check that. If the plate is free to pivot in its holder, like along an edge, the edge that is close to the center of rotation might yield a hologram since it doesn’t move as much as the edge further from the axis, flapping in the breeze so to speak, moving more than the tolerance.

Keep up the good work, this is part of the pain of the learning process, but you are definitely making progress!

[Holomark]

Thank you both for the replies.
Regading the image color - Each of the plates were left to dry by air - no blow dryers...
I will have to try the potassium bromide. Now I am wondering if the development process causes shrinkage which results in a change in color of the H2 - was the H1 (which was processed using the same method) also subject to shrinkage? I would expect so, then... Would the addition of the potassium bromide then increase the brightness or efficiency of the H1 (transmission)?? And would this result in a brighter H2 (if everything else were left the same). I am guessing that the shrunken fringes are less efficient when the H1 is replayed with the same laser used to create the H1.

As to the viewing angle. I was originally hoping that I could go from a small H1 to a larger H2. Now I realize that doing so would result in a slightly larger viewing angle but also result in the inability to see the whole image at many angles.
Now I expect that the aperturing effect is even more limited that the position of the two plates. Am I correct if my belief that the viewing angle is going to be limited by the position of the transmission hologram and the two frames. By this I mean if the H1 was positioned 7 inches from the H1 plate when shot, I can not increase the viewing angle by placing the H2 plate 2 inches from the H1 plate. I presume that I will only be able to see what is in the line of sight of both plates and the image.

Time to shoot some more plates. I do seem to be making some progress. I am happy that I have now produced something is recognizeable as a hologram with three dimensions.

[Dinesh]

Now I am wondering if the development process causes shrinkage which results in a change in color of the H2 - was the H1 (which was processed using the same method) also subject to shrinkage?

If the H1 shrunk, then the maximum replay angle would shift. That is, the brightest reconstructed image would be a few degrees off the angle at which you shot it. So, if you simply replaced the reversed H1 plate in the holder and the H1 did shrink, the image would be slightly dimmer than it could have been.

Am I correct if my belief that the viewing angle is going to be limited by the position of the transmission hologram and the two frames.

Yes, and the image position, ie the image planing. Usually, the image is planed right at the H2, so the image planing is usually not an issue. When you look at an H2, you're effectively looking at it through a "ghost" H1 sitting virtually above the H2. This is the virtual viewing window. So, you can get a rough idea of these windowing effects by actually placing a piece of glass of the same size as the H1 between you and the H2 at roughly the same distance from the H2 as the original object was from the H1 (assuming image planing at the H2). This piece of glass is the viewing window on the H2.

[holorefugee]

When going for brightness H1s are really important. As Dinesh mentioned, the fringes are roughly perpendicular to the plate in a transmission hologram. Shrinking has little effect and it can be corrected by tilting the H1 till the image is brightest when projected on a white card in the H2 film holder. Since you can control the reference to object ration in the H2 the absolute brightness is not that big of a deal. The noise is very important. Make sure your H1 does not have any "fog" surrounding the replayed image.

Getting the H2 bright is all about getting a bright object beam but no letting any reflections off the object interfere to make new holograms. (Intermodulation.) Then you have to get the exposure correct. I find that being within a power of 2 is pretty good so If 15 seconds does not work then move to 30 not 16...

Also, Green H2s appear brighter as the eye is more sensitive to green light. (We will ignore photopic and scotopic vision for the moment.)