Well I guess it is generally understood that DPSS green LD are not suitable for holography. I'll assume that dye lasers aren't either because no one uses them. So why are they useless for holography? Do they not run TEMoo? Are they not spacially or temporally coherent? Not enough coherence length? Just curious.
I have no clue as to why Dye lasers aren't more popular... I'm sure there are 'perceived' specific issues such as nasty chemicals, broad line widths, pumps, weird mechanicals, bulky sizes, and other general fears. While they can be 'tuned' via changing out their dyes,it is not all that easy to do. I have seen a couple of designs based on ‘cartridges’, so that a certain dye could be loaded quickly and even fluid pumped non contact... pretty cool huh!
There are distinct differences in how they are pumped also....flash lamps, NdYAGs, Nitrogen Lasers, ...Argons. Some are Q-Switched, some are CW, some are just pulsed, etc. Properly designed, they work as well as ANY other laser for Holography. Some dye lasers have their dyes in polymers and some in glass...as well as in a fluid.
I bought a dye laser about two years ago, and have never even fired it up! It is an early prototype, kind of modified version of this unit:
The specs are very similar though, except mine has been modified as a test model and so is not quite as pretty! lol I don't plan to use it for Holography though, well, not in the sense of generating a result that is great to look at and show my friends...lol, so I’m not talking!, as I would get barbecued on this list by the Display folks as a heretic!... Let's just say, it'll be cooling some really really really!, cool stuff.
So then, given that, I won't be reporting on my work, but maybe someone else here who has used a dye laser explicitly for Display Holography will step forward and ...be loved by all!?? Let's see.......
I was just curious to know why not use them to obtain the 2 primary colors r, g, and b to do color holograms with 1 laser. Sounds like it might be even more troublesome (and perhaps expensive) than 3 seperate lasers especially considering blue LDs are on their way though albiet expensive and only now more powerful ones (25+mw) are coming out.
I think you are absolutely correct of course if starting from scratch, but skill with a tool can overwhelm this 'factoid'. If for instance YOU were adept in Laser DYES, then you would consider it easy to put together a three or more color system. Remember that conversation taking place on gamuts?... well, Laser Diodes are NOT at the optimized positions, and quite frankly are NOT going to be available in all the colors of the rainbow for about....50 years! Which is longer then I would care to wait. Laser Dyes are available in many many color bandwidths! and the same cog that pumps one fluid through one cavity could pump the fluid through 8 cavities! So an 8 color Dye laser using dichroic combiners is just a simple scale up...IF you develop the expertise to work with the things! But of course, almost none do. And certainly Holographers, for all their enthusiasm for a truly full color Holographic capability are not spared the ravages of procrastination and laziness afflicting ALL Humans...too bad too, cuz it would be neat to see a Projected Reflection Hologram mastered with a DOZEN true spectral differenciations. I think there are a number of breakthroughs out there that are not yet marketed that are going to make such Holograms relatively common place in the next half decade and NOT made on tables, or with homemade equipment!...So,... in 5 years which Holographers will have taken the opportunity to play with Dye Lasers???... we'll see.....one, maybe two??? lol Its all about the opportunity to learn more and more...yet dye lasers are just too 'uncomfortable' to work with, for most.
It seems like white light gas lasers will be ready before dye lasers. I have heard of people in light shows using them. A friend in Seattle has bought a few on ebay with sucess but I can't get him to measure the liewidth. Has anyone tested them?
Are you speaking about Krypton Argon Mixed Gas Ion Lasers??
The two gases mixed together are a bit weird. These are not actually 'white light' per se, but more like several lines that appear 'white' to the naked eye (an eye not wearing clothing or shoes). There is a slight doppler broadening of each of the gases’ standard separated behavior, mostly due to the fact that Krypton is a very large atom in comparison to Argon (about twice), and so that creates a situation where the pure kinetic energy of the Krypton during cataphoresis., acts like a school bully in the hallways shoving the heck out of the argon up against the lockers (glass pores) and even into them, as kind of a 'gettering' process called Krypton Burying.! Plus keep in mind that each of the gases really need their own concentrations of atoms, electrical current, best temperature, and capullary size, so its more of a shotgun marriage! That is why the really good Mixed Gas units have small reservoirs of gas controlled by solenoids to keep the balance (sounds like the modern marriage huh?) ...sadly the mix ratios are done almost entirely by hand! For Laser Light shows, people like Floyd at the PSC, employ a kind of spectral calibration done by eye, by the artists. For Holography mixed gas units are...too chaotic, too iffy, not very stable. One would do better to run both an argon and a krypton separately through a dichroic combiner!
Now on the other hand, that is not to say it couldn't be! I think it was Lexel that had mixed gas lasers based on Invar resonators, and automatic mixing...not sure of specs!., they were very nice. Let me go look.....
There aren't really any comprehensive specs online though, but a phone call would probably work?!
As far as features necessary for their use with Holography, there is no mention of automixing, gas seperators, zeeman controllers, multi-capullary diameter tubes, multi-anodes, etc....so ........1) they are probably still, NOT going to work well enough, and 2) they ARE still...expensive. Which ones did your friend get?
I remember a talk by Nick Phillips in the mid '80s where he reported his experiences with dye lasers. He essentially said that the hassle of their operation made their use impractical. Of course, any holographer with access to lots of money (for the dye laser(s), pump source(s), and the technician to keep them all aligned and balanced) should be able to make them work.
>Well I guess it is generally understood that DPSS green LD are not suitable for holography.
Clearly laser pointers may not be suitable without
major reconstruction, but for larger DPSS lasers holography is well
possible; one can even buy single mode types off the shelf (perhaps
not quite cheap, though).
I know people who have build their DPSS by themselves, usually for
show applications. Once the resonator is big enough, it shouldn't
be too difficult to equip it with an etalon and achieve single mode
operation. However, the total costs (for say, 100mW) would be in
the order of the price of an used argon (say, approx $1000), and
given the risk that it may not satisfyingly work, or that one ruins
the expensive IR diode, an argon is the better bet right now, IMHO.
But on long-term, DPSS are the future, as prices for diodes and
crystals go down all the time. To build a DPSS would be a wonderful,
demanding hobby project, I think the main problem right now is the
lack of a proven plan for a DPSS suitable for holography. It it
would exist, I would start building one by tomorrow, for the sake
of it ! (and for getting rid of the 4KW power draw and the water
lines of my argon...)
The construction would be mechanically involved, I guess a piece
of cake for Colin, but more of a problem to people like me without
machining tools. If someone would sell the difficult mechanical
parts of a proven design (once set up and CNC machined), I think
it would be a gold mine . Here some links of sites I happen to
know : http://www.eiergeier.at/dpss.htm http://www.laspro.de/body_a.htm
These are from the german speaking laserfreak community, where
there is a great expertise of building such things.
<The construction would be mechanically involved, I guess a piece
of cake for Colin, but more of a problem to people like me without
machining tools.>
Thank you for the compliment but I too would have a hard time building the optics mounts that need to be adjustable in 3 axis as well as TEC controlled. I am hoping to have a plan in the near future. I have been working with a laser designer to make a single mode plan available for experimenters. I can only fund the project as the money surfaces however.
> I'll assume that dye lasers aren't either because no one uses
them. So why are they useless for holography?
With etalon and good resonator design single mode would in
principle be possible, and the advantage would be the possibility
to tune through the whole visible spectrum.
But the easy dye lasers are pulsed and this is of limited use; I
wonder how difficult adjustment to single mode would be in this
case . Pumping could be done by a home-made nitrogen laser,
but I doubt that the energy of a single pulse would ever be big
enough for holography use (usually they have a high repetition
rate, like 10Hz, with a few tens of mW of average power; but the
different pulses wouldn't be coherent with each other, so a single
pulse would have to be used).
Then there are CW dye lasers, but those are typically pumped with
a high power argon laser or frequency tripled NdYag, making this
not worthwhile. The whole setup, incl stabilizing the dye jet,
would IMHO be far out of reach. Perhaps one of those medical units
could be converted, though.
> Then there are CW dye lasers, but those are typically pumped with a high power argon laser or frequency tripled NdYag, making this not worthwhile. The whole setup, incl stabilizing the dye jet, would IMHO be far out of reach. Perhaps one of those medical units could be converted, though.
lol no way!, this baby is not for a 'display' type of Holography. Do you know what it cost?.... no, I need it for cooling.
Yes I know that they cost alot when new, but I have seen some of them on ebay once in a while. I could imagine that when fitting it with a prism plus etalon, such a baby may be useful (tho I doubt it's be worth the effort).
. Here some links of sites I happen to
