Anyone ever make Lippmann plates?

[holmburgers]

Thanks PE... I was way off.

 

[holmburgers]

http://www.ilfordphoto.com/holofx/holofx.asp

A possible development in the Lippmann world (and what a vibrant world that is! ). The question is, are they suitably panchromatic?

Available for sale at freestylephoto.biz. Prices are pretty high, but only $4.5 per 2.5"² plates.

 

[BetterSense]

That link doesn't work for me.

 

[holmburgers]

fixed it

thanks

 

[holmburgers]

So, over the weekend I finally shot and developed a plate. I've got photos that I will post this evening, and although I haven't been able to successfully view interference colors, the whole thing is nonetheless fascinating and quite unlike any other silver-halide film I've ever dealt with.

It was late last night, so it's possible that diffuse sky-light will aid in seeing the colors.

One thought that helped to reinvigorate my interest in interference "heliochromy" was learning about first (or front) surface mirrors. http://en.wikipedia.org/wiki/First_surface_mirror

You can buy these mirrors for reasonable prices (http://howardglassco.thomasnet.com/...ies/94-r-front-surface-mirror?&bc=100|3001011) and you can actually make them yourself quite easily from a cheap mirror.

It seems to me that if you coated these plates with a Lippmann emulsion, all conditions of "optical contact" between mirror & emulsion would be met.

Now, the thing that has me wondering is whether or not you can just leave the emulsion on the mirror during processing & for viewing. There seems to be some disagreement, or at least a lack of clear concensus on this.

J.S. Friedman in the History of Color Photography clearly states that the mirror must be present for viewing, and that this is of course difficult with mercury. However, people here on APUG have seen Lippmanns where their very own eyes, and with no reflector present. Furthermore, an old post on the holo-wiki archive has a discussion wherein FSM's are mentioned, but people seem to be saying that the emulsion needs to be removed from this for viewing.

So who the heck knows?!

Let's try to figure this out... because this seems like a home-run technique for modern day Lippmann photography.

 

[Photo Engineer]

The Lippmanns that I saw had no Mercury as far as I could determine. They did not seem to be heavy at all. But, they were in a frame and I could not even tell for sure if there was a mirror present. I suspect that there may have been a mirror to enable the image to be as bright as it was in each of these. They can be made available for viewing during the October workshop at GEH.

PE

 

[Hologram]

Now, the thing that has me wondering is whether or not you can just leave the emulsion on the mirror during processing & for viewing. There seems to be some disagreement, or at least a lack of clear concensus on this.

You can leave the emulsion on the mirror for processing, Chris - but not for viewing. To what extent this is doable practically is another matter (you've to struggle with two opposing issues: on the one hand the emulsion must remain on the mirror/glass plate during processing and on the other hand, you have to be able to remove the developed layer from the mirror without damaging it subsequently).

J.S. Friedman in the History of Color Photography clearly states that the mirror must be present for viewing, and that this is of course difficult with mercury.

I've Just had a look into Friedman: "...the illumination of these plates must be in accordance with the taking scheme; that is, with a mirror in contact with the print so that standing waves will be reformed. For this reason, the plates can be viewed only at a certain critical angle."

Friedman is just plain wrong about this. Obviously, he is confusing the mirror (reflector, mercury layer etc.) used during recording with the glass wedge, which the Lippmann photograph used to be optically contacted to for better viewing. The 10° wedge simply serves to shift the viewing angle away from the specular reflection of the glass surface.

 

[Struan Gray]

Bear in mind that most metals which are good for making a front surface mirror will be affected by the processing of the emulsion. Platinum or Palladium are (perhaps) exceptions, but not cheap. Aluminium, nickel or other shiny, broadband reflective metals will all be etched and/or interfere with the photographic reactions. Gold is yellow.

If you have a set of silver fringes suspended in gelatin with the right spacing, they will automatically reflect light back at the right wavelength. The effect will be strengthened by reflection off the back of the emulsion. The refractive index mismatch between gelatin and air will do this on it's own, but silvering the back will make the effect stronger still.

These days, I suspect the best method would be to vacuum coat the rear of the emulsion with Aluminium after processing.

 

[holmburgers]

Martin, thanks for the response, that's precisely the line I was referring to.

I wondered if that could be the case; I know that even the most careful of researchers can be mistaken. Perhaps it is corrected in subsequent editions? My book is from 1946 (IIRC), 1st edition.

However, Struan's post puts us back in contradiction; saying that the reflector will strengthen the effect.

Can the reflector remain for viewing or not? :confused: that is the question

It seems that with the reflector present, there would be no way to produce a black.

 

[Struan Gray]

I have not made or seen Lippmann emulsions, but I am a physicist. You don't need a metallic mirror to get a strong reflection (jewel beetles and morpho butterflies do very well with lamellae of chitin and air). However, the silver lamellae in a Lippmann emulsion are created with a metallic reflecting surface on the back of the emulsion, and it seems clear that reproducing that metallic coating will maximise the wavelength-specific reflection when viewing. The phase shift when light reflects off the back of the emulsion will be the same with or without a metallic layer, but the strength and wavelength dependence will certainly be different.

Black you get by destructive interference. The light is either absorbed, or scattered to non-viewing angles.

 

[holmburgers]

Thanks Struan. Indeed it does seem reasonble that a reflector would help the viewing, but with all the talk against it I'm wondering what the deal is.

I'm curious to see what Hologram will have to say.

Back to the aluminum; what problems might this pose for processing?

 

[Struan Gray]

An aluminium front surface mirror will be clouded and/or etched by quite weak solutions of either acid or alkali. Most developers and stop baths would do the trick. If the gelatin is porous enough to develop the emulsion fully the Al is likely to be corroded. You might be able to do something with a barrier layer of hardened gelatin.

Al ion in solution also interfere with the balance of Ag redox reactions. Most darkroom books advise against using Al trays for this reason. I'm not enough of a darkroom chemist to say how bad the effects are, but the warning makes sense to me.

I'm about to go into radio silence for Midsummer celebrations - please don't interpret any lack of response as indifference.

 

[Hologram]

However, Struan's post puts us back in contradiction; saying that the reflector will strengthen the effect.

No, it won't. If it would, wouldn't then all interference filters and reflection holograms have such reflectors?
A reflector may severely weaken image contrast and add noise (reflections).

Can the reflector remain for viewing or not? :confused: that is the question

It can't. All the Lippmann photos I've seen (made on AgX materials) reveal their color effect but on the emulsion side. That might be different though with high index modulation materials like DCG etc.

 

[Hologram]

I have not made or seen Lippmann emulsions, but I am a physicist. You don't need a metallic mirror to get a strong reflection (jewel beetles and morpho butterflies do very well with lamellae of chitin and air). However, the silver lamellae in a Lippmann emulsion are created with a metallic reflecting surface on the back of the emulsion, and it seems clear that reproducing that metallic coating will maximise the wavelength-specific reflection when viewing. The phase shift when light reflects off the back of the emulsion will be the same with or without a metallic layer, but the strength and wavelength dependence will certainly be different.

I guess there's a difference between the Lippmann lamellae and say those of a Morpho butterfly wing. In the Lippmann case you're dealing with a volume recording medium. From what I read about the Morpho butterfly structures, I got the impression they mainly involved surface relief effects (perhaps akin to a "blazed hologram").

An aluminium front surface mirror will be clouded and/or etched by quite weak solutions of either acid or alkali.(...)

Al ion in solution also interfere with the balance of Ag redox reactions. Most darkroom books advise against using Al trays for this reason. I'm not enough of a darkroom chemist to say how bad the effects are, but the warning makes sense to me.

I don't know either. But regarding front surface mirrors I'm sure most of them have a very thin protective(MgO, SiO2 etc.) coating on the aluminium layer.

However, the silver lamellae in a Lippmann emulsion are created with a metallic reflecting surface on the back of the emulsion (...).

... a "bunch" of silver nanoparticles, Ag or AgCl/HgCl2, maybe even HgAgCl2 (after a mercuric chloride bleach) within a gelatin matrix. In any case this is not plain silver.

 

[holmburgers]

Ok, the fact that you view the color from the emulsion side is probably the most important fact here. Indeed, Friedman is completely wrong in this case.

I'm very interested in what you physicists and "hologramistes" can do for a modern day reflector. Martin, you mentioned aluminized PET and methods to destroy the reflector, and then Yve's Gentet is supposedly working on such a means as well.

Here's a theoretical proposition... is there another liquid that would be easier to work with than mercury and more reflective than no mirror whatsoever? For instance, would there be an advantage in using water as opposed to no reflector at all. In the reflector-less, Bjelkhagen method (we'll call it), the reflection comes from the emulsion-air interface, correct?

I'm just wondering if there's another option that hasn't been tried yet, but I admit to asking this in total ignorance of the necessary conditions.

Struan, as for Midsummer... har de bra!

 

[holmburgers]

Lippmann

Here are several views of my 1st Lippmann plate, or at least an attempt at it. It's from the same batch of plates that R Shaffer used and by the way Rob, did we ever figure out what the actual emulsion was? I seem to recall that the lady from Laser Reflections gave us something different than Slavich PFG-03C, which is what we originally inquired about.

It was developed with GP-2 in the A+B manner described earlier and advised by Darran Green.

It was soaked in a 10% solution of chrome alum for 10 minutes, 3 minutes in the developer, an 8ish minute wash & a couple minutes soak in a 2% glycerin solution.

My solutions were probably too warm, at 20-21°C, whereas 18.3° (65°F) is recommended. Next time I'll cool them down.

To be honest, none of these pictures show any interference color effect. I believe the plate was generally underexposed and the subject is quite far away. Next time, I'll choose a bolder composition that compliments the small format.

Yes, that's me sitting next to a motorcycle.. I enjoyed trying to sit still for the 6 minute (f/11) exposure, but pesky mosquitoes started biting me at about 3 minutes and at that point I resigned to being a blur in the final image.

The only point where I can see interference colors that resemble reality are in the gas tank, which is Honda's lovely 1971 Candy Gold. There is a distinct gold hue at this point, and it stands to reason as the gas tank was perhaps the only point in the scene receiving full sunlight & exposure (it's quite reflective as well).

I chose a particularly dicey lighting situation (contrasty), sitting under the patchy shade of a hedge tree in early evening.

The strange brown hue visible in one of the pictures is the emulsion side, the same side that in the other pictures looks like a beautiful mirror. Very strange. You can also see evidence of the border where the plate was resting on the mat-board frame. I'm wondering if my "light sink" fabric is doing a good enough job..

The holder was very easy to make, and fun.. but just don't make it until you've measured your plates...! An easy way to do this in the dark is to mark the edges of the plate(s) with a pencil on paper. I ripped out the center divider of a normal double sided cut-film holder and glued the fabric and mat-board frame to the backside of the other darkslide.

 

[Hologram]

Here's a theoretical proposition... is there another liquid that would be easier to work with than mercury and more reflective than no mirror whatsoever?

The only thing that comes to my mind are the metals pointed to in the IBM's US 4054453 - mainly gallium that is.

For instance, would there be an advantage in using water as opposed to no reflector at all. In the reflector-less, Bjelkhagen method (we'll call it), the reflection comes from the emulsion-air interface, correct?

Yes. For the history records, the "Bjelkhagen method" has been invented by Hermann Krone(1894).
I assume water won't work in this case because the index difference at the emulsion/water interface will be too small. If you want to dig further, I think the whole thing relates to Snell's law (see http://en.wikipedia.org/wiki/Snell's_law).

 

[R Shaffer]

Here are several views of my 1st Lippmann plate, or at least an attempt at it. It's from the same batch of plates that R Shaffer used and by the way Rob, did we ever figure out what the actual emulsion

Good on ya Chris for giving it a go.

We have the GEO-3 plates.

IMO you've got a couple places you could try adjusting

I made my plate in bright mid-day sun 2min @ f/8 and that seemed a bit overexposed. But it was even illumination. So your possibly underexposed.

Gotta get your temps down and keep them reasonably consistent from bath to bath.

Other than that, looking forward to seeing your next try.

 

[holmburgers]

Thanks Rob. Yes, it's about time I gave it a go.

The answer seems fairly self explanatory, but I'll ask anyways... why such low temps? Is that pretty standard for holographic materials?

As for the exposure, the white paint on my gas tank is that dark, solarized, blue color, while the gold paint gets the interference colors. So I'm both over & under it seems, but generally it was tough light to shoot in, and I knew that going into it.

I'm also looking forward to giving it another go, and sooner this time. The whole procedure was pretty easy, and I spent more time mixing the chems than shooting & processing.

Gallium seems very interesting. It looks as though it was first made in 1875, so it definitely stands to reason that Lippmann might not have known about it, or enough quantity didn't exist on the face of the earth at the time! Surely mercury would've been easily available and cheap.

Any idea what kind of quantity one would need, theoretically? It's density is 6.1 g/cm³. 100 grams will cost you $170 from one supplier, but undoubtedly there are deals out there. Very intriguing...

Thanks for the word on Hermann Krone.

 

[Mustafa Umut Sarac]

Chris , all laser experiments , interferometry done at where the air fluctations are low. So may be they do all these experiments at cold weathering because air come to ground.

 

[R Shaffer]

Perhaps because we want to alter the gelatin as little as possible and warm solutions may swell the emulsion. In my case, mostly because the instructions I was following indicated 65deg max.

 

[Photo Engineer]

The melting point of unhardened gelatin is approximately 68 deg F. Above that temperature, it will melt and dissolve in the processing solutions.

PE

 

[Struan Gray]

Back from midsummer. It was fun.

I don't want to speculate too much on whether or how a reflector improves the viewing of Lippmann plates. I haven't made or viewed them, and it seems impertinent to lecture to those of you who have. Kudos for giving this a go.

However, basic physics can help to understand why some things work and others do not. For example, if you want a strong reflection at the surface of the emulsion you need to provide a sharp mismatch in the refractive index.

Metals do this for free. This isn't the place to learn about refractive indices in metals, but in short, for light below a certain frequency, usually in the UV, metals have zero or very low real refractive indices. That means the refractive index difference is similar to the refractive index of gelatin, around 1.5.

Transparent materials like glass and air mostly have refractive indices between 1 and 2. To get an index mismatch as large as that between gelatin and a metal you would need to get up to 3 or more, and even diamond is only 2.5. The highest index oils for immersion microscopy are around 1.8-1.9. There are materials with higher indices, such as most semiconductors, but they absorb too much to be useful as mirrors. Basically, any non-metallic reflector is going to give you a much weaker reflection.

One reason the interference in a Lippmann plate is weak is that your light is incoherent. A laser can fill a thick emulsion with fringes, but incoherent light does much worse, even if it is filtered to be monochromatic. A rough rule of thumb for thermal light (black body radiation, aka sunlight) is that the coherence length is of the order of the centre wavelength. In layman's terms that means you can only expect to get two or three fringes. It's one reason why Lippmann emulsions are thin: there is no benefit to a thicker emulsion, it just wastes silver and absorbs and scatters light.

You can probably maximise your chances of getting good fringes by reducing the range of angles at which the light strikes the emulsion. Smaller f-numbers are the easiest way to do this, but retrofocus or more exotic telecentric designs will help too.

FWIW, the Morpho butterfly scales are 3D on the nanoscale. The remarkable thing about the Morphos is not that they have lovely colours, but that their colour is so strong, and so pure, over a wide range of angles and lighting conditions. If you could somehow reproduce their method of generating colour, and vary it across a substrate, you would be a very happy camper indeed.

 

[holmburgers]

The problem with the reflector, and the thing that didn't occur to me until I had a go at it, is that you view the interference colors by looking at the emulsion side. In the film holder, the light passes through the glass substrate to the emulsion and into blank space where it is ideally not reflected back by the velvet, and interference arises from the RI difference between gelatin & air (2 & 1.5, right?)

So, for a reflector to work in the way you describe, it would have to "disappear" and "re-appear"; switching its position in relation to the emulsion.

Interesting about coherence and use of higher f/stop. That would be an interesting thing to test out, and fairly easy. I don't know if we can tolerate much more of an increase in exposure times though..

Actually, I think the long exposures are one of the most enjoyable things about this kind of photography.

Herbert E. Ives did an investigation on Lippmann photographs while at Cornell (I believe) and utilized a technique pioneered by Cajal. This technique involved swelling the material so that the fringes were brought into the reach of microscopic investigation. He discovered that the fringes only went so deep, but determined that this was due to the sensitizing method, which had been by bathing the plate in dye solutions. So, Ives incorporated the dyes into the emulsion and was apparently able to get much deeper fringes and better color.

He also made 3-color images with Lippmann plates, but that's a tale for another time...

 

[Hologram]

One reason the interference in a Lippmann plate is weak is that your light is incoherent. A laser can fill a thick emulsion with fringes, but incoherent light does much worse, even if it is filtered to be monochromatic. A rough rule of thumb for thermal light (black body radiation, aka sunlight) is that the coherence length is of the order of the centre wavelength. In layman's terms that means you can only expect to get two or three fringes. It's one reason why Lippmann emulsions are thin: there is no benefit to a thicker emulsion, it just wastes silver and absorbs and scatters light.

I agree. By "volume recording medium" I didn't advocate using "thick" recording layers for Lippmann photographs. That's why commercial holographic AgX emulsions, which usually are around 8um thick, are certainly not the best solution for Lippmann work. On the other hand, these materials have been greatly improved. Scatter becomes very negligible with grain sizes <10nm - even for blue and violet radiation.

By the term volume medium I was referring to a recording medium that records the interference fringes within the depth of its layer (and be it only a 2um "thick" layer). That would be in contrast to a surface relief structure, say a photoresist. Maybe I'm wrong but I believe you could not record a Lippmann photograph as a surface relief structure.

By the way, regarding filtered incoherent light, it's possible to make reasonably good contact copies from holograms.

FWIW, the Morpho butterfly scales are 3D on the nanoscale. The remarkable thing about the Morphos is not that they have lovely colours, but that their colour is so strong, and so pure, over a wide range of angles and lighting conditions. If you could somehow reproduce their method of generating colour, and vary it across a substrate, you would be a very happy camper indeed.

Yes, they're truly amazing. See: http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-5-4-87