Ye Old Red Sensitive DCG

[Johnfp]

Thanks to the brilliant Jeff, I may be trying this soon but I have a question.

If you make red sensitive DCG, can't you expose to red green and blue? Or does the dyes in the red sensitive DCG adversly affect the blue and green absorptions?

[Joe Farina]

As I recall, Jeff Blyth's "ye old red sensitive DCG" is pretty sensitive to red and blue (but not green), when using MB dye. There is another dye mentioned in his papers (I forget which one) which can provide good sensitivity to green and blue (but not red). It was stated that these dyes could not be used together for full RGB sensitivity.

If you can get your hands on some Rhodamine 6G (not an easy task) then you can combine this with MB and the rest of Jeff Blyth's system for full RGB sensitvity via the "Chinese" method of Zhu et al.

But I would just get your feet wet with HeNe and the "standard" ye old DCG with MB. There will be enough differences between regular (no dye) DCG and dye-sensitized DCG to keep it interesting for quite a while

[Martin]

As I recall, Jeff Blyth's "ye old red sensitive DCG" is pretty sensitive to red and blue (but not green), when using MB dye. There is another dye mentioned in his papers (I forget which one) which can provide good sensitivity to green and blue (but not red).

No, it's not in his paper. it's been mentioned in his patent, GB 2232263. The green sensitive dye was phenosafranine. However, I do know that later Jeff had found safranine-O to be an even more efficient sensitizing dye at 532nm.

If you can get your hands on some Rhodamine 6G (not an easy task) then you can combine this with MB and the rest of Jeff Blyth's system for full RGB sensitvity via the "Chinese" method of Zhu et al.

I'm still uncertain if the highly fluorescent R6G will lead to increased scatter...

[Johnfp]

Yea Joe, I only have a red laser ATM.

I have like 6 DCG plates in the fridge in my lab that I forgot about. They are like 9 months old. I looked at them and they have not darkened at all. I may use them as a base and try some things so that I can expose them to red. I read Jeff site a few times and it seems I need more the methyl blue to get a little speed increase. Althought I may not worry about speed as I am sure I can set up a SBR and do extreemly long exposures. I may just soak one of them in a solution of McCormic blue dye, let it expose for 20 minutes and see what happens. Hate to throw them away.

I always wanted to try the sugar free blueberry gelatin too.

[Joe Farina]

As I recall, Jeff Blyth's "ye old red sensitive DCG" is pretty sensitive to red and blue (but not green), when using MB dye. There is another dye mentioned in his papers (I forget which one) which can provide good sensitivity to green and blue (but not red).

No, it's not in his paper.

Jeez Martin, it's in his paper from Applied Optics 1991, page 1601: "It has been found that by substituting the dye eosin Y for methylene blue one can produce bright green reflection holograms at an exposure level ~50mJ/cm2 of 514-nm light."

In an earlier paper (SPIE 1212, page 195) he mentioned riboflavin in combination with MB for full-color hologram recording. In the patent, he makes the comment that "riboflavine also gives sensitivity to green light and phenosafranine gives sensitivity to blue light."

Scatter due to rhodamine 6G? Scatter from what? Scatter occurs from particles, not dye molecules. The rhodamine is used in very small concentrations, and even if there is some fluorescence, that would just cause some extra bias hardening and not scatter.

[Martin]

Jeez Martin, it's in his paper from Applied Optics 1991, page 1601: "It has been found that by substituting the dye eosin Y for methylene blue one can produce bright green reflection holograms at an exposure level ~50mJ/cm2 of 514-nm light."

You're right of course - thanks for the clarification.
I just meant to stress on Jeff's later findings, which seemed to have led him to prefer phenosafranine and then safranine-O as the green sensitizer. Regarding safranine-O it has an absorption peak close to 530nn. Moreover, it's probably less toxic than R6G

In an earlier paper (SPIE 1212, page 195) he mentioned riboflavin in combination with MB for full-color hologram recording. In the patent, he makes the comment that "riboflavine also gives sensitivity to green light and phenosafranine gives sensitivity to blue light."

Right. The four dyes he mentions in his patent seem to provide real panchromatic sensitization.

Scatter due to rhodamine 6G? Scatter from what? Scatter occurs from particles, not dye molecules. The rhodamine is used in very small concentrations, and even if there is some fluorescence, that would just cause some extra bias hardening and not scatter.

Maybe, I don't know, I keep wondering. Some years ago, in one of our former photopolymer system R6G did produce a fair amount of scatter. But maybe you're right and this won't be an issue with DCG.

[Dinesh]

Scatter due to rhodamine 6G? Scatter from what? Scatter occurs from particles, not dye molecules.

Depends on the size of the molecules and the sort of scatter. Very small molecules can Rayleigh scatter, since Rayleigh scattering occurs for sizes smaller than the wavelength of light. A typical size for a single atom is about 0.05nm (Bohr radius), so a molecule consisting of some 100 150 atoms is prone to Rayleigh scattering. Larger molecules are prone to Mie scattering. For example, biological cells Mie scatter.

The rhodamine is used in very small concentrations, and even if there is some fluorescence, that would just cause some extra bias hardening and not scatter.

It's possible, depends on the wavelength shift in the scattered radiation. For example, a blue light fluorescing to a red light would not cause extra bias hardening. However, the presence of a red dye might transfer the red energy into the Cr site. The whole field is made more complex by the exact caprture cross section of the various elements. If the capture cross section were wrong, then scatter would occur.

[Paulos]

..................
If you can get your hands on some Rhodamine 6G (not an easy task) then you can combine this with MB and the rest of Jeff Blyth's system for full RGB sensitvity via the "Chinese" method of Zhu et al.
..................

Zhu's paper: "True-color reflection holograms recorded in a single-layer panchromatic dichromated gelatin material"
pdf file: http://www.google.gr/url?sa=t&rct=j&q=% ... 8A&cad=rja
Has anyone here tried this method for panchromatic DCG holograms?

There is a source of commercial grade Rhodamine 6G on eBay now from seller "scuddlebutt3", costs only ca. 10$/20gr.
http://www.ebay.com/itm/Fluorescent-Dye ... 25634c8ee6

[Joe Farina]

Thank you Paulos for the link to scuddlebutt3. In addition to the Zhu method (haven't been able to try it yet), rhodamine 6G improves the sensitivity of "regular" DCG to green light, see "Improving the holographic sensitivity of dichromated gelatin in the blue-green part of the spectrum by sensitization with xanthene dyes," Dejan Pantelic and Branka Muric, Applied Optics 10 June 2001, Vol. 40, No. 17, pages 2871-5. Maybe this is available online?

[jsfisher]

Thank you Paulos for the link to scuddlebutt3. In addition to the Zhu method (haven't been able to try it yet), rhodamine 6G improves the sensitivity of "regular" DCG to green light, see "Improving the holographic sensitivity of dichromated gelatin in the blue-green part of the spectrum by sensitization with xanthene dyes," Dejan Pantelic and Branka Muric, Applied Optics 10 June 2001, Vol. 40, No. 17, pages 2871-5. Maybe this is available online?

It is not available online for free.

The article explores xanthene dyes to improve DCG sensitivity in the blue and green regions of the spectrum. I have not yet read the article, but from its abstract, it claims that from a reference point of ~215 mJ/cm^2 for pure DCG and green, the sensitivity improved to ~140 mJ/cm^2 with Rhodamine 6G and to ~90 mJ/cm^2 with Erythrosin B.

Doesn't DCG sensitized with the G307 formulation fall in the 5-20 mJ/cm^2 range? If so, are the xanthene dyes all that interesting, still?

Another question, if G307 DCG were also dyed with methylene blue, would it be sensitive to red at a similar (5-20 mJ/cm^2) level?