Holographyforum.org / holowiki.org

this is a idea to improve color saturation
If you have a old lcd montor around the house you can get the rgb matrics from it, when you take it apart you will find on the lcd a film on both sides this is the polarizer film..you need to remove this on both sides (back & front).
I was reading a paper where this was tried to improve one of the problems with color holography that is saturation. altho they never explained where to get the rgd matrics...I found this is a good source to get one

Danny have you the link for this paper?

Sergio.

And what would be the efect of the matrix?

I think it was called nonoverlapping spatial multiplexing. This might be the paper:

http://www.ncbi.nlm.nih.gov/pubmed/20062131

Sorry, not open access. Of course in those days we did not have the matrix elements that are common now, so we'll have a better chance today to make this work.

Thank you Kaveh, this is the exact name and inventor, with the actual technology we can make it work with better studies, I plan setup a lab for this direction in colour holograms.

kaveh1000 wrote:I think it was called nonoverlapping spatial multiplexing. This might be the paper:

http://www.ncbi.nlm.nih.gov/pubmed/20062131

Sorry, not open access. Of course in those days we did not have the matrix elements that are common now, so we'll have a better chance today to make this work.

Oh, wow. The paper is from 1967. The author was addressing image cross-talk (e.g. the red ghost image formed by the red light interacting with fringe patterns originally created by green). Non-overlapping spatial multiplexing was the first technique the paper describes (using a slotted mask, beam splitter, mirrors and color filters to create the two separate color grids--would a simple fine mesh screen work for the mask?).

The second technique is more curious, at least from my point of view. It "involves coding the reference beam so that each colored reference wave varies in a unique manner over the hologram plate." The author used a ground glass screen as his reference beam coding plate.

thanks for finding the paper.. I was looking all over for it, I know i read it in several books refering to color holography problems and how to overcome them.. i hope to try this soon

With just the abstract of the paper in hand I can't be sure I am right, but this sounds like making full color holograms by what 100 years ago was called an additive color technique. If I am right, this would be a new version of one of the various color screen processes, the great majority of which used one or another regular line filter arrays, either singly in sequential or color-separated exposures, or in combination on one filter in one shot. These processes, such as the Paget, McDonough, Omnichrome, Joly and Dufay all gave reasonably good results, but suffered from the intrusion of the screen pattern when modestly enlarged. Only the Lumieres' Autochrome and the Agfa AgfaColor escaped this by using random color screens, the former with potato starch grains and the latter with dye-stained droplets of shellac. Enlargements could still be pleasing because the grain was random and the appearance was one of the paintings by Seurat.

I would expect the improvement in saturation would be gained at the expense in resolution for the above reasons.

For more history see:

http://www.luminous-lint.com/IaW/public/5/1/2/1/0/20/T/

or two of my entries in The Encyclopedia of 19th Century Photography:

http://books.google.com/books?id=PJ8DHB ... or&f=false
and:
http://books.google.com/books?id=PJ8DHB ... or&f=false

I think you are right, walschuler. It is exactly the ideas of additive color photography in early 20th century. Of course color holography is additive by its nature anyway. But it is fascinating how holography mirrors early photography, e.g. Lippmann photograpy.

kaveh1000 wrote:Of course color holography is additive by its nature anyway.

Is it? This is something I have been thinking about for a while now. Consider that an additive system, such as a colour TV, emits R,G and B in appropriate quantities to achive a particular colour balance. However, the TV itself emits the appropriate "wavelengths". If you illuminate a printed sheet with a white light source, then any colour is achieved - "emitted" - by selective absorption of the "unwanted" colours. This is a subtractive colour system, since it "subtracts" by absorption all the undesired "colours" (wavelengths). Now consider the colour of a coloured object. When an object is illuminated by white light , then again, certain "colours" are absorbed by scattering processes and whatever's left is emitted in order to give a colour to the real-life object. Is this additive or subtratctive? The coloured object does not emit it's own radiation, but radiates the illuminant after selective absorption. Consider now a colour hologram. In this case, there are two processes - the recording and the reconstruction. In recording the hologram, the illuminant is some mixture of RGB (and I'm ignoring the fact that the object in a colour hologram is illuminated by coherent radiation, since the coherence of the illumination is required only for fringe stability and not for the colour characteristics per se) whose ratio is given by some appropriate colour map - usually the CIE 1931. If the object re-emits this with no absorption, then the object is, in effect, a mirror, which brings up the point: Is a mirror illuminated by coloured light an additive or subtractive system? Now consider the reconstruction of a colour hologram. In this case, the hologram is illuminated by white light and emits colour by Bragg selection. This means that unwanted colours - wavelengths - are absorbed, and what's left is emitted to give a specific colour. In other words, the colour of a reconstructed colour hologram depends on the colours in the illuminant that are absorbed. This sounds like an subtractive system.

Therefore, I would argue that the recording of a colour hologram may be an additive system (what colour is a chameleon on a mirror?), but the reconstruction of a colour hologram by selective absorption of not-colours is a negative system.