Danny Bee wrote:hey i was thinking on trying Chlorophyll with dcg to extend to red, dont know if it will work but got a good collection of it now very dark green
Sounds like a great idea Danny. BUT have you checked the price of it from Sigma after they have boiled up their spinach? It is:-
Over $30,000. per gram!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Now I just know you could supply folks here after boiling up your own spinach for just $2
per gram or maybe $ 20 with a bit of profit motivation thrown in! And Dave could even modify his coating technique to cope with
spinach modified DCG for red lasers.
and now,
Back on the serious discussion on dichromate concentration dilemma.
As the exposure progressess the light to the object increases too as the yellow Cr IV gets converted to the lowly absorbing green CrIII. I think that this going to be a much bigger effect with low initial dichromate concentrations and exposure to high- efficiency blue light than with high concentrations and very low efficiency 532nm green light. I suppose what this all boils down to is the question for everyone here:-
Where is the concentration level point of diminishing returns in diffraction efficiency for a given laser’s wavelength and power?
Jeff
wow Jeff maybe i can get rich and retire, thats so funny.
it was dinesh that suggested it, he said go out in back and get leaves and grass and boil it a few mins, and put it in alcohol for bit.....I did and its nice and green....should i add a bit of tea too?
Danny Bee wrote:wow Jeff maybe i can get rich and retire, thats so funny.
it was dinesh that suggested it, he said go out in back and get leaves and grass and boil it a few mins, and put it in alcohol for bit.....I did and its nice and green....should i add a bit of tea too?
Hey it is your birthday today Danny, maybe someone got you some!?
Danny Bee wrote:wow Jeff maybe i can get rich and retire, thats so funny.
it was dinesh that suggested it, he said go out in back and get leaves and grass and boil it a few mins, and put it in alcohol for bit.....I did and its nice and green....should i add a bit of tea too?
Hey it is your birthday today Danny, maybe someone got you some!?
good catch Tony ! your birthday package is in the mail danny !
I think the answer is based on the regulated optical density required for produce a good reflection hologram as pointed By Dupont, 0.3 - 0.4 (?). So the amount of absorbing material (DYE or Cr) can be determined with thickness of absorbing layer, and extinction coeficient of Cr material at wavelength used to record and using the Beer's law.
However with the Cr IV conversion to Cr III is a kind of bleaching process that must be measured, because we break the Beer's law linearity:
The incident flux must not influence the atoms or molecules; it should only act as a non-invasive probe of the species under study. In particular, this implies that the light should not cause optical saturation or optical pumping, since such effects will deplete the lower level and possibly give rise to stimulated emission.
So with the bleaching rate we must compute the non linearity onto equations and solve it in terms of Kogelnik parameters.
Sergio
jeff-blyth wrote:
Danny Bee wrote:hey i was thinking on trying Chlorophyll with dcg to extend to red, dont know if it will work but got a good collection of it now very dark green
Back on the serious discussion on dichromate concentration dilemma.
As the exposure progressess the light to the object increases too as the yellow Cr IV gets converted to the lowly absorbing green CrIII. I think that this going to be a much bigger effect with low initial dichromate concentrations and exposure to high- efficiency blue light than with high concentrations and very low efficiency 532nm green light. I suppose what this all boils down to is the question for everyone here:-
Where is the concentration level point of diminishing returns in diffraction efficiency for a given laser’s wavelength and power?
Jeff
Sergio wrote:I think the answer is based on the regulated optical density required for produce a good reflection hologram as pointed By Dupont, 0.3 - 0.4 (?). So the amount of absorbing material (DYE or Cr) can be determined with thickness of absorbing layer, and extinction coeficient of Cr material at wavelength used to record and using the Beer's law.
However with the Cr VI conversion to Cr III is a kind of bleaching process that must be measured, because we break the Beer's law linearity:
The incident flux must not influence the atoms or molecules; it should only act as a non-invasive probe of the species under study. ..........................................................
So with the bleaching rate we must compute the non linearity onto equations and solve it in terms of Kogelnik parameters.
Sergio
[/quote]
Yes that is a good point Sergio. If we start off with say absorbance 0.4 (if that is what DuPont suggest) then the situation improves as the exposure progresses and CrVI goes to CrIII (BTW sorry I got my Roman numerals wrong in last post). Using systems with dyes like Methylene Blue in photopolymers, the effect is much stronger and you can see the object brightening up within seconds after exposure due to a bleaching effect, but you of course know all about that. It is nice though to have for once a phenomenon working for us instead of against us is'nt it?
Jeff
