DIGITAL HOLOGRAM PORTRAITS #7 -- 5/02/04
SINGLE STEP LCD HOLO PORTRAITS:
I'm writing this from my hotel room on the road.
As you may recall from earlier posts, I have been looking into the method of creating these portraits in one step -- bypassing the mastering process entirely -- creating a one-step, "direct" white-light reflection portrait. To achieve this, it will require dual-masking (slits), and each set will have to be identical and accurate. I am not sure at this point in time without experimentation, if doing these by hand, rather than mechanically, will be an issue with quality, since the resulting holographic portrait will have to be viewed through the slits directly. My thoughts on this is currently centering around the bleaching process minimizing this issue -- but still having to view directly through the recorded slits none-the-less. There will be no room for inaccuracy.
Regardless, I have a high level of confidence that the overall process will "work" -- which will, at the very least, provide a foundation for any improvement, if needed, further on down the road. Only testing will show for sure one way or the other.
If you'll recall, when creating a laser-transmission master for transfer, only one set of slits is required, since the laser light from both the reference beam and object beam passes through the slits to the holographic plate from the same side. With a single-step reflection hologram, two sets of slits will be needed simultaneously -- with the front set limiting the reference beam, and the associated second set limiting the object beam (approaching from the opposite side of the plate, hence a reflection hologram) . . . slit / holographic plate / slit.
Each set of slits will have to correspond to the other -- in other words, reference beam slit #1 will have to correspond with object beam slit #1, and so on and so forth.
The resulting 3-dimensional image will reconstruct "within" the hologram, however -- not as an image plane, as with the end-result of the two-step method. Whether this will be a drawback or not remains to be seen. The distance from the plate to the LCD screen will have to be determined as well. This distance must allow the viewing of each entire image through each slit -- just as with the laser transmission hologram -- or the end result will just be eight slits of a 2-D image, without the merging of images into a single 3-D image. This is an area of concern -- since we do not want the image reconstructing too far back into the hologram . . . if for no other reason than for sharpness when reconstructed. The two-step method provides an image right in the plane of the holographic plate itself, provides a razor-sharp image as a result, not to mention the visual impact of the reconstructed image being "right there" at the surface of the plate.
I'm not quite sure if this method would provide the same visual impact of the two-step method -- at least without the specialized optics and mechanics (for accuracy) used in previous one-step automated machines such as the SONY unit, which provides an image-planed hologram. I'm concerned about what the required the distance will be between the LCD and plate -- and the associated reconstructed image being too far back in the hologram. We'll have to see.
In any case, I wanted to post this as food for thought while on the road to let those following this process know that I do feel that a one-step method is within reach and possible -- even if only the foundational work of said method. I really don't know where this all came from tonight, as I was asleep and woke up with all this in my head, came over to laptop here (it's after midnight) and just began typing. Maybe I'm still half asleep and I'll be embarrased in the morning when I'm fully awake and realize that this was just a pipe dream. But I don't think that it is.
Beginning Wednesday, Deb will be traveling out to meet up with me, then we're both off for a few days of vacation at Lake Erie. Quite a bit of final preparation must be made before doing any testing of this single-step direct method, and there are other areas already in progress with the two-step method that need to be completed first -- not to mention "everyday" work and other projects going on. Everything in its time. When the time comes to do testing, if it works, great. If not, well, that's what experimentation is all about. In science, even failed experiments are a form of success in their own way: Listen to your failures and what they are trying to convey . . . usually they'll tell you everything you need to know for the next time around.
Back to bed.