Colour Holography: The Ultimate Imaging Technique for Museums
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Bjelkhagen, Hans I.
An overview of the colour holographic recording technique is presented. Colour holography is the most accurate imaging technology known to science. It is now possible to produce 3D holographic images for display that are almost indistinguishable from the original object or scene. Colour holography offers an alternative route for the display, dissemination, study and investigation of rare or fragile or culturally sensitive artifacts. It also offers a route to novel display techniques and enables museum objects too fragile for normal display to be shown. An advantage is that rare, precious or high value artifacts can be displayed without any concern about theft or damage thus reducing costs for insurance, shipping, etc. Until recently display holography was usually associated with monochrome 3D imaging. After the appearance of colour holography it has become possible to record holographic images of 2D objects, such as oil paintings. A holographic contact recording of a painting reproduces the painting with all its surface texture details preserved, such as brush strokes, the painter’s signature, etc. Possessing an exact copy of the painting could be important for insurance and restoration purposes, in case of theft or damage. The paper also discusses the rendition of colour in a hologram. The major advantages of holographic reproduction are discussed together with its limitations.
 As chairman of the Royal Photographic Holography Group, I wanted to welcome you and also to tell you a little about why 2008 is an interesting year, because it marks a 60th anniversary of holography, that then the way then is that we introduce it in line holography for microscopy. And then of course, so that is extremely important. And then of course, after the 60s, when lasers came about and we could make holograms with lasers, the whole world would know about holography, but not really until then. The other anniversary is a Nobel Prize in photography in 2008, even to Professor Gabriel Littmann, who invented calligraphy, still the best form of calligraphy ever achieved. And that is of course something that most photographers have not even heard about, nor have they seen any small photograph. And when I talk about that is how the important photography is for museums. When black and white photography came about, the museum started to use black and white photography to bring photographs of artifacts or of ceramics and other things, so the rest of the world knew that they never could have that. And that then changed the course and came about, the calligraphy came about, it would make beautiful reproduction of a lot of things. Like paintings, other artifacts and whatever, that you want to express of the world without having to travel everywhere. With calligraphy now we have actually got the possibility not even to reproduce anything, we can actually show it the way it is. Without having the object there, what we can do now when we introduce calligraphy, we go from a possibility to record a field of life that is emitted from an object store that, and then replay that forever without having to have the object there. And when you go to a museum, most of the artifacts, you are not allowed to touch or they even are put very often behind glass. So why do you really need to have something behind glass when you can give the same effect by just looking at the image of it, like looking identical to the object? The same goes with paintings. Oil paintings, for example, are now often protected with a piece of glass so people don't come and spray paint on them. And that means of course that why do we need to have a painting behind the glass when we can have exactly the same sensation by the hologram of the painting. And of course this looks a little strange to people in museums, but photography looks strange, everything looks strange in the beginning, but sooner or later museums will take advantage of it. And what I'm going to show now is where we stay today. We are not really there yet, but we are on the way. So within five, ten years, I think we will have techniques that are absolutely amazing. Okay, so let me start with my first slide. What I'm going to talk about, I can also tell you, you know, normally I work at Optic Technion in North Wales. There we have the Centre for Modern Optics where we develop material, we develop polypony and also holographic elements, polypony and a variety of other optics related techniques. And Optic Technion in itself is an interesting building which was actually set up to develop, create new companies in optics and incubator, it's not like the universities of research and development center to create new business in optics. Anyhow, so we are also part of the University in Rexham. So, I'm operating the slides. Okay, so this is Optic Technion in Wales and this building is from, it's covered, the whole front here is covered with solar panels for your solar, for photovoltaic, and this is the largest area in Europe just now. Okay, now let's go to the holography and particular for museums. So during our and when introduced his first hologram in April 1964 of the train, the toy train, he got the whole world got extremely amazing. And then after that a lot of development went on in the holography to develop these techniques, including display of course that one we are focused on today and then a lot of other applications came along, interferometry and optical elements, computing and rated holograms. But let's focus now on display today. So during these years from that time until I will say 2000 or so there have been some very, very few actually examples of holograms used in museums. All these holograms have only been made with one laser so far and that means you can only record one of them, although you can tune them to different colors. But there was the main practice and museums of course today in the world of color, where you have color TV movies, everything is in color and come with a 3D technique without color, we didn't appeal to museums. So that means that we had to wait until and that's where we are today. So we don't know what will happen in museum, but at least we have a chance now to get the interest from museum. And what I'm going to show some during that time what I have done, some of the more interesting ones I have done since 1969 when I started in photography. Okay, the first thing I did was in 1974 in Sweden, I worked in Sweden, I am from Sweden, so I started that. I did the crown of Erik XIV. They had a stamp exhibition Stapholmia 74 and they had made these stamps of the crown and of course they couldn't move the crown out to this exhibition so they asked me to make a hologram of the crown and show it at the exhibition there. So if you go to the next slide, there you can see me recording the crown in the cellar of the castle August the 20th during the night we were doing it. And this of course is again monochrome hologram and this is actually the first type of hologram of Axis Transmission Holograms that need lasers of notary lamps to reconstruct them to show them at an exhibition. We spend a lot of work on that and it was one of the most important thing for people there. I have never had so many people come into a stamp exhibition. They didn't come for the stamp, they came for this. You can see the exhibition now at the exhibition there in the cellar before next slide please. So here is the cabinet that they made. There is the hologram and of course in this case we used a mercury oplam with a yellow filter to make it go. So it looks rather good here as you can see but of course the lack of the rubies and so in the crown doesn't show. Nevertheless it was the first time Swedish people saw the hologram at all. So it was very successful. Next slide please. The other thing is which is again something that now is important for museum is the possibility in local museums to show things that they can't because the National Museum may want to have it. So a gold collar was found in the river in Sweden in 1827. It's from about 500 AD and it is kept at the Museum on National Landtrip with this in Stockholm. But the local museum wanted to also show it so the only way it could do it was to order a hologram to show it. Next slide please. Here you can see the hologram again we go to this is a reflection hologram now and that was done by Holovision in Stockholm the company I was running when I was in Sweden. This was done in 1980 and the museum was Farbiddhams Museum or where they found in that area this gold collar. Next slide please. And this you can see the installation we did get the museum. So here is the hologram and explain what it is. It has these holograms should really be done with like 45 degree tilt and the spotlight should be just about straight out like that. Then nobody will see the spotlight nor would they realize that there is any particular strange with this. It's just the object is there in the little box like the other things you see here. And of course that at that time that was the best we could do. The next best to the real thing now of course color photography has completely changed this. Next slide please. Okay let's go now to recording of color holograms. The problem we don't see much holograms. There are only a few people in the world and today we actually have one of these people here as well. A few from Russia but also Yves Chalte who has been working hard on this for the last 10 years. Anyhow what we need is panchromatic materials. That's something you can't go up and buy. They don't exist with the resolution we need. The reason is that when you want what is called blue light, blue light status when it hits a plate and they will by looking making this hologram look like looking through a ground glass. You put a ground glass and an object behind it. How can you ever get a hologram? So that's why Artfa Info the Northeast product material they had in the 60s until they all stopped making them towards the end of 90s or even earlier. They were useless for holography. So we have to develop our own materials and that of course makes it almost impossible to commercialize it as of today. Anyhow we need three ways at minimum. You will see how many we really need for work. In any type of photography or other you normally use the Maxwell's free color theory but holography use where narrow bandwidth bases to you need more. Also the other thing that almost most projects in holography many of them have failed because nobody knows how to like holograms properly and they ignore that problem. So that is often a reason why the project failed. Also cost until we now have color now even the display of them have become even more critical than before. Not only can you restore to image but by you don't have the right angle you restore the colors. So there has to be absolutely accurate installation of the color holograms. Next slide please. Here you can see the example of what happened when you use convention like an alpha plate and trying to make a color hologram. This is an object. This is an object with a pure gloss plate. This is one of the ultra fine emotions in front of the object in the laser and this is an alpha plate. So any person who tried to the whole hologram think they can use an alpha plate the result will never be better than this. Next slide please. And then we have a run a project with a student that brought the DPSC student to develop color holography and he was doing computer programs to simulate how many wavelengths you need to actually make a color hologram where the human eye really can't detect the difference from the real object and the holographic image of it. So here you can see that with three inlaysers immediately when you go to four wavelengths you get a dramatic degree and then it slowly increased when you come to around nine wavelengths. Next slide please. And we look at up to seven wavelengths. That means that these are the wavelengths that it looks like this max system can't get the right dimension because the errors have disappeared out to the right. The screen looks not matching. I don't know. Mac people may know how to correct this but nevertheless it's these are the wavelengths for three ways as the optimum. Four, five, six and seven. Of course we don't have these wavelengths in lasers easily available so still we have problems to really develop color holography. Next slide please. Here is what we did. This is a familiar Macbeth color target. This is the color target element with three lasers and here is a color hologram of it. And what we did is account the error in each of these patches how accurate they can be recording. You can even see going from the real thing using now digital photography which in itself is not working to reproduce colors well. So then you go from this to the laser. So the laser we only see this three lasers and you can see here that the colors are not right. So what we did we calculated each of them and see how well they can be reproduced theoretically. Next slide please. Here you can see we have three lasers and here are the errors on each of these patches. They vary depending on some of the wavelengths are better for this particular color but worse for that and so forth. So we try to get the average down to the minimum. Next slide please. When we switch to four lasers we have immediately much better. So the error is down zero zero two not in power error as an average on all these patches. Next slide. And this is down now with five wavelengths. So there is a dramatic difference between going between three and four. So any serious application for new seams will require four lasers for and the four which I just showed you. Next slide here you can see that all of them on the same slide. So we go from three four and five. So four is a really and then we'll see if you need to take it in. It depends on the people in the museum that come and say that this is not the real thing it's a hologram. And if they say that we have not reached the glory. Next slide. Here is how we do it now. We had three different lasers. A good one for red. We have a CW nearly a leg laser for the green frequency double and an urban ion laser for 76. And then we combine them with beam combiners that takes the red send it through and add the green and add the blue and send both of them. We have a shutter and then we have the so-called Dennis Yurt setup. When I talk about Dennis Yurt that may not be familiar to people not in our geography but Dennis Yurt was a person who invented holography in the former USSR almost simultaneously as anything in the United States. He used what we call the single beam reflection holograms and that technique is the most suitable for museums because that provide you with a 180 degree Pw in both dimensions which is a requirement from museums. You don't want to have a box that you just have to stand in a particular position to see the rainbow away there and then of course you lose the illusion of having the object and it's gone. So we only work with the Dennis Yurt technique. And next slide please. Here is our lasers in optic. These are the two. Drifton and Arvon and the near-linear. We send the beam. This is a laser that may be generated and then from mind goes into another room and then you see the white beam going into the recording room. And this is from the laser into the recording room. Next slide please. The reason why we have separated them is that the lasers are terrible at noise sources with the transformers. We don't want to have them at all present nor on the table nor in the room where we record holograms. That's a general rule in holography but even more important when you work with color holograms. You may have an exposure time of 20 seconds or so. Then you will create vibrations if you don't have an absolute silent area where you work. And here is that we have a huge table here, a very heavy table sorted on a German system to stabilize these two lasers so they are floating together in two different rooms. So an extensive system that works extremely well. The hologram alignment in or stays over weeks without getting misaligned even when you work on two different tables. Next slide please. Here is all the equipment we use to measure our holograms with this spectra-pupram meter here. So you can look at the hologram and measure the colors. Next slide please. Now we come to the spotlight which has been as I saw very important for color hologram because when you make the hologram you take the colors you want to achieve is the colors that your spotlight is going to emit. So you have to set the ratio between your lasers to mimic that. You can't take the color hologram that you have recorded that and take it out in the sound. Then they will completely blueish. So the hologram can only be made for a particular spotlight. That's it. And then they also have to have a specific angle which is exactly the same angle as you use. Then you recorded it. The spotlight has to be provided of course you have no shrinkage in the emulsion. And of course shrinkage is out in the color emulsion because then you destroy the color. So our emulsions have absolutely no shrinkage. Next slide. Here is a commentant that similar to what we have now. This is a spectrum from background. Mostly they meet in red as you know it's very little in blue. And the sun of course has much more in blue. So if you want to make the hologram that works in the sun you have to adjust three wavelengths so they will match that. Next slide. Then of course something has happened is new LED lights. They are extremely interesting because now if you get the right wavelengths as we use for recording you can match that with an LED and all the rest of the light is not illuminating the plan. So that would give you plates that are much higher contrast because you only illuminate it with a light that is coming back. Or unfortunately not yet we have such lights that really work well. There is still a lot of work to be done and also to have done combine these into a white good light LED. But we are working on it and that is soon we would have such lights that would be the perfect light source for color holograms. We can have see some of the advantages in the next slide. Long lifetime. I mean we don't need to walk everywhere and change them. That's another problem with holograms on display. People ignore to switch the lights if they burn off. They are holograms in museums. They can be for a year without the light before they say. Here at least you can guarantee that if you have a hologram on display it will stay live all the time. Small size improve the sharper images as you have a better spatial piltry. They are very robust. Heat is generated which is another source in a holographic museum. If you have a light it gets very hot and you need to have that conditioning. And also so that there are only advantages that we can develop holographic LED lighting. Next slide please. Here are some examples of our silver cross emulsion which was done on a consortium in Europe to develop a suitable image of the color holographic. The possibility of that is some sources of that and mainly from Russia. Russia for the holography has been well known for the superfine grains since the beginning. Then it is really needed. Much higher resolution than it needed to do it. So Russia has been the leader in that. But unfortunately it is very difficult to buy any color material in Russia. As well it is very difficult to find it anywhere else. Most people like me and Jean Thierry they don't really deliver emulsion to send it to anybody. So that means that we have to make our own. But this consortium I was looking into can we commercialize this emulsion and that's the question. Next slide please. So here you can see the object itself and the hologram of it. This is a spectrum with the same spotlight that we use to illuminate another object and here is with this particular point. And then you can see what light is built up with. As of course it's not identical. If we had a few more here the difference between them would be less and less. But even now it's very good. I have the holograms here so you can look at them later. And this is the error in X and Y. So no sorry this is the coordinates. This is the coordinates of the object and this is the coordinates X, Y and the spectrum of the hologram on Y. Y is of course very difficult to get perfect in a calder hologram. Next slide. Here is another example I brought. I use this because it has a lot of blue. Blue is the most difficult calder to record without scatter and that's why we need nanometer, nanometer, grain size of salt to record that. Our emulsion is in the order of nanometer measured by the microscope. Next slide please. Here again you can see now that we are looking in the blue part of the element that we know of course now has a stronger contribution here in the blue and less in red. You can also see something interesting here. The wavelengths we use are 647, 532 and 476 and they are identical so there is absolutely no shrinkage in our plate before and after processing and recording. This is also a must for calder holography. Next slide please. And displaying as I said that I can only see that the holograms can be used with fixed installation. There is no way you can put a hologram on a journal or anything and people will ever see a color hologram. So you have to have fixed installation in museums and so wall mounted holograms with overhead track lighting and the track lighting should go in the opposite direction that they should not go along with the wall. They should have tracks for a perpendicular to the wall for each hologram so you can adjust the angle by moving them back and forth. So museums need really to rearrange if they want to show holograms. I mean there are these things with extended lights that you see here. That's okay for small but if you think that you have a big hologram square meter and you want to extend it's like 10 meters out hanging out from the frame it doesn't look aesthetically good. So these are things that one has to get away from. It has to be fixed installation with either integrated lighting in some way or in museums from the war. As I showed in this museum long time ago the best is to have them tilted over five and overhead light and hide that light so nobody sees it. That's the most nice way of showing reflection holograms. Next slide please. And then I want to just say something about potential application and color application. So this is just to show of course this is art education I think is one you can say. Every museum in the world every art school in the world could have a fantastic collection of the most beautiful art pieces for students. They don't have to travel around the world to see that. They can have this library they go and look at. Any type of the old artifacts of whatever paintings or sculptures and so on. Next slide please. Here is an example of cuneiforms I have done for a German museum. And cuneiforms need to be tilted to read the text. So the photographs of cuneiforms are no good for the people who that's why they really want to have a color. Color may not be that important for this type of collection or artifacts but nevertheless we go to the next slide and now you can see the advantage of holography because when you want to read this text what you do is you hold it in your hand and retrieve them with the light moving across. So now any person that wanted to study these artifacts they don't want to send them around to scientists they want to send holograms of them so of this type so they can read the text and do their research. Next slide please. This is another one I have brought here and you can see I have all of these holograms that I show if you want to look at them as holograms. Next slide. This is another thing where you can think maybe for advertising also that you don't need to have expensive stuff out in airports of course a lot of interest for people and safety issues so why not just have holograms in these boxes. So can be animated at the critical meeting. So the important thing to see here is how the reflections really move across when you go around as if they were actually inside that box. So this is one of the people that we really amazed when we see things like that they can't believe that there is nothing behind the glass. Next slide. This is another example of Russian egg which is again you can see how this point that comes from the spotlight goes on the surface as if that was how it was hit of the real object. So this really shows the advantage of holographics a dynamic image as well. This was the lead of the Symbacrosse mansion for the National History Museum in London and they were very pleased with this type of technique so now museums are really interested in holographic but there is a long way to go across before we will see that it can be commercialized. Next slide. Now I talk finally about oil paintings that may not be what to think of because holographics really do but let's show you what the holographic can do. Next slide. Here is an original oil painting nothing particular it's a very cheap one but I use that because it was painted on wood and it has very marked strokes of the brush. So here is a holographic reproduction only with free lasers so of course the color reproduction is not perfect but it's not that bad certainly as good as color photography. Next slide. But the advantage for the painters or the painting in interest is that you can go in the hologram in large areas so you can study in that hologram of the painting the paint strokes. Also things like this which is in the original of course you can find here in the hologram identical to that. The reason the color has changed here from there is not that the color is wrong it's just because you need to tilt the hologram so it goes out of the correct reference beam which affects the color but then you can see these effects. So defects are just these particular that of course would be a way to identify a stolen painting when it comes back. Is this the same painting that was stolen? So insurance company in the future may require or certainly multi-million paintings should have a holographic reproduction in the insurance company if something happened. That can also be used to restore the damaged painting. Next slide. Here is one of my own collection of paintings from Peter van Gravel 1629 to 1790. It's a holographic reproduction and you can also see you know how the light is showing this structure in the painting. This is on the canvas and we can easily record that as well just putting the holographic paint on top of the painting. Next slide please. This is the final slide or almost final but this is what we think holography will do. I had there is something that you will hear about later. I have now focused on the perfect for pure holographic technique. There are techniques where we can use computers and photography and combining to holography which I have a lot of interest in. You will hear more about it from other speakers. I didn't talk about that because I am mainly interested in holography that can make images that are identical to the regular work. And these computer and photography since photography is integrated in the system you can never get it because you have to capture the light as coming from objects holographically to get something that is identical to the object itself. So the virtual image behind this type of hologram is today the most interesting image we can get. And also the extensive field of human about 180 degree in both directions makes it impossible to see that something is strange within it. And the way from reconstruction of the actual critical only the light that has scattered off the object during the recording that's why it's so important to have exactly the right wavelengths and enough of them to make that happen. And as far as I can see it may happen during my lifetime but definitely in 50 years time I can tell you that holography will be all over the world of this type of kind. There is no doubt about it. And it's a picture that the photographic companies today are so they have perfect equipment but they don't look far enough. They get rid of beautiful recording systems, huge field coatings because the only material that is silver hang out and also we don't hear there are new materials coming out there in the photopolymer. So there are a lot of interest in the old type of silver photography and auction techniques and that will only expand over the coming years. So next slide please. So as I said people often ask me can you send me a photo of your hologram and say why should I send that is useless. Why not I can as well send you a photograph of the object itself you already have it. The only way you can see it is to look at the hologram itself and that's why for those who have never seen this hologram I have brought all of them here that you have seen so we can look back there and mean a break. Next slide please. Okay any questions? Yes? I mean we need to have some coherence aboard that way it goes without saying also that a meter or more. We talk about here what we do size updates we can do. We need to have at least the coherence to take the depth of this hologram. So the other thing where lasers have to be absolutely stable output if you set them up and record them in the meantime the red lasers have changed you can't get white anymore. New changes in the output from the three lasers will combine into the wrong color. So you have to have the best lasers in the world which doesn't mean that you have no coherence to do this. Yes? I know that one of the main lines out of that are the lasers for a certain what's the percentage loss you have to put up with to rate it come out at four seven six. It is like half. Yes but the 488 is not the new way it's a new green and it's not good for reproducing white. I won't be able to record for 488 or something but they have no output enough. There may become new solid state lasers in the future that will have better colors for color but again they are very hard to get them in the car we need. Yes? I'm completely not used to this but is there any danger that the laser which is shot through the objects might damage the view? No no I mean this is of course it's a very good question if you don't know it. The amount of laser light hitting them is nothing compared to if you use a flash and take a photograph of an object you probably need more light to it and the laser lasers are needed over a longer time during the recording so we may have 20 seconds if you take a flash photograph you in a millisecond but even if you use pulse lasers which can be used at 20 nanosecond lasers there is no risk because if there was a risk you would completely burn your emulsion it would completely be destroyed when you send the light through it so there is no risk to go there everything you need to be aware of is of course you should test them if there is some very delicate textile that you could bleach by the immediately pure image that could be the only thing I can think of but I think that on the mind is in the pyramids they have paintings inside they can't show it to people only can switch on light occasionally. If you could make green very metallic holograms so then you can make another cave outside where all these holograms of the wall paintings are put up again and they can be only at night for years or because the advantage of a hologram it doesn't have any pigment or any dyes in it so it's a pure physical way of regenerating the light so you can never bleach. I mean there are things that could happen that's more environmental thing you need to see them but if you do that they will survive hundreds of years with exactly the same color. The best example of that is Hickman photography that I mentioned about Hickman who got there I may have to stop now because we are late so I think we can discuss more things in breaks and so and I think we have to stop the question because we are late with the problem so thank you very much. Thank you.
 As chairman of the Royal Photographic Holography Group, I wanted to welcome you and also to  tell you a little about why 2008 is an interesting year, because it marks a 60th anniversary  of holography, that then the way then is that we introduce it in line holography for microscopy.  And then of course, so that is extremely important. And then of course, after the 60s, when lasers came  about and we could make holograms with lasers, the whole world would know about holography,  but not really until then. The other anniversary is a Nobel Prize in photography in 2008, even  to Professor Gabriel Littmann, who invented calligraphy, still the best form of calligraphy  ever achieved. And that is of course something that most photographers have not even heard about,  nor have they seen any small photograph. And when I talk about that is how the important  photography is for museums. When black and white photography came about, the museum started to use  black and white photography to bring photographs of artifacts or of ceramics and other things,  so the rest of the world knew that they never could have that. And that then changed the course  and came about, the calligraphy came about, it would make beautiful reproduction of a lot of things.  Like paintings, other artifacts and whatever, that you want to express of the world  without having to travel everywhere. With calligraphy now we have actually got the possibility  not even to reproduce anything, we can actually show it the way it is. Without having the object  there, what we can do now when we introduce calligraphy, we go from a possibility to record  a field of life that is emitted from an object store that, and then replay that forever without  having to have the object there. And when you go to a museum, most of the artifacts, you are not  allowed to touch or they even are put very often behind glass. So why do you really need to have  something behind glass when you can give the same effect by just looking at the image of it,  like looking identical to the object? The same goes with paintings. Oil paintings, for example,  are now often protected with a piece of glass so people don't come and spray paint on them.  And that means of course that why do we need to have a painting behind the glass when we can have  exactly the same sensation by the hologram of the painting. And of course this looks a little  strange to people in museums, but photography looks strange, everything looks strange in the  beginning, but sooner or later museums will take advantage of it. And what I'm going to show now  is where we stay today. We are not really there yet, but we are on the way. So within five, ten years,  I think we will have techniques that are absolutely amazing. Okay, so let me start with my first slide.  What I'm going to talk about, I can also tell you, you know, normally I work at Optic Technion  in North Wales. There we have the Centre for Modern Optics where we develop material,  we develop polypony and also holographic elements, polypony and a variety of other optics related  techniques. And Optic Technion in itself is an  interesting building which was actually set up to develop,  create new companies in optics and incubator, it's not like the universities of research and  development center to create new business in optics. Anyhow, so we are also part of  the University in Rexham. So, I'm operating the slides. Okay, so this is Optic Technion in Wales  and this building is from, it's covered, the whole front here is covered with solar panels  for your solar, for photovoltaic, and this is the largest area in Europe just now. Okay,  now let's go to the holography and particular for museums. So during our  and when introduced his first hologram in April 1964 of the train, the toy train, he got the whole  world got extremely amazing. And then after that a lot of development went on in the  holography to develop these techniques, including display of course that one we are focused on  today and then a lot of other applications came along, interferometry and optical elements,  computing and rated holograms. But let's focus now on display today. So during these years from  that time until I will say 2000 or so there have been some very, very few actually examples of  holograms used in museums. All these holograms have only been made with one laser so far and that  means you can only record one of them, although you can tune them to different colors. But  there was the main practice and museums of course today in the world of color, where you have color  TV movies, everything is in color and come with a 3D technique without color, we didn't appeal to  museums. So that means that we had to wait until and that's where we are today. So we don't know  what will happen in museum, but at least we have a chance now to get the interest from  museum. And what I'm going to show some during that time what I have done, some of the more interesting  ones I have done since 1969 when I started in photography. Okay, the first thing I did was in  1974 in Sweden, I worked in Sweden, I am from Sweden, so I started that. I did the crown of  Erik XIV. They had a stamp exhibition Stapholmia 74 and they had made these stamps of the crown  and of course they couldn't move the crown out to this exhibition so they asked me to make a  hologram of the crown and show it at the exhibition there. So if you go to the next slide, there you  can see me recording the crown in the cellar of the castle August the 20th during the night we  were doing it. And this of course is again monochrome hologram and this is actually the first type of  hologram of Axis Transmission Holograms that need lasers of notary lamps to reconstruct them to show  them at an exhibition. We spend a lot of work on that and it was one of the most important thing  for people there. I have never had so many people come into a stamp exhibition. They didn't come  for the stamp, they came for this. You can see the exhibition now at the exhibition there in  the cellar before next slide please. So here is the cabinet that they made. There is the hologram  and of course in this case we used a mercury oplam with a yellow filter to make it go. So it looks  rather good here as you can see but of course the lack of the rubies and so in the crown doesn't show.  Nevertheless it was the first time Swedish people saw the hologram at all. So it was very successful.  Next slide please. The other thing is which is again something that now is important for  museum is the possibility in local museums to show things that they can't because the  National Museum may want to have it. So a gold collar was found in the river in Sweden in 1827.  It's from about 500 AD and it is kept at the Museum on National Landtrip with this in Stockholm.  But the local museum wanted to also show it so the only way it could do it was to order a hologram  to show it. Next slide please. Here you can see the hologram again we go to this is a reflection  hologram now and that was done by Holovision in Stockholm the company I was running when I was  in Sweden. This was done in 1980 and the museum was Farbiddhams Museum or where they found in  that area this gold collar. Next slide please. And this you can see the installation we did get  the museum. So here is the hologram and explain what it is. It has these holograms should really  be done with like 45 degree tilt and the spotlight should be just about straight out like that.  Then nobody will see the spotlight nor would they realize that there is any particular strange  with this. It's just the object is there in the little box like the other things you see here.  And of course that at that time that was the best we could do. The next best to the real thing now  of course color photography has completely changed this. Next slide please. Okay let's go now to  recording of color holograms. The problem we don't see much holograms. There are only a few people  in the world and today we actually have one of these people here as well. A few from Russia but  also Yves Chalte who has been working hard on this for the last 10 years. Anyhow what we need is  panchromatic materials. That's something you can't go up and buy. They don't exist with the resolution  we need. The reason is that when you want what is called blue light, blue light status when it  hits a plate and they will by looking making this hologram look like looking through a ground glass.  You put a ground glass and an object behind it. How can you ever get a hologram? So that's why  Artfa Info the Northeast product material they had in the 60s until they all stopped making them  towards the end of 90s or even earlier. They were useless for holography. So we have to develop  our own materials and that of course makes it almost impossible to commercialize it as of today.  Anyhow we need three ways at minimum. You will see how many we really need for  work. In any type of photography or other you normally use the Maxwell's free color theory but  holography use where narrow bandwidth bases to you need more. Also the other thing that  almost most projects in holography many of them have failed because nobody knows how to  like holograms properly and they ignore that problem. So that is often a reason why the project failed.  Also cost until we now have color now even the display of them have become even more critical  than before. Not only can you restore to image but by you don't have the right angle you restore  the colors. So there has to be absolutely accurate installation of the color holograms. Next slide  please. Here you can see the example of what happened when you use convention like an alpha  plate and trying to make a color hologram. This is an object. This is an object with a pure  gloss plate. This is one of the ultra fine emotions in front of the object in the laser  and this is an alpha plate. So any person who tried to the whole hologram think they can use  an alpha plate the result will never be better than this. Next slide please. And then we have a  run a project with a student that brought the DPSC student to develop color holography and he was  doing computer programs to simulate how many wavelengths you need to actually make a color  hologram where the human eye really can't detect the difference from the real object and the holographic  image of it. So here you can see that with three inlaysers immediately when you go to four wavelengths  you get a dramatic degree and then it slowly increased when you come to around nine wavelengths.  Next slide please. And we look at up to seven wavelengths. That means that these are the wavelengths  that it looks like this max system can't get the right dimension because the errors have  disappeared out to the right. The screen looks not matching. I don't know. Mac people may know  how to correct this but nevertheless it's these are the wavelengths for three ways as the optimum.  Four, five, six and seven. Of course we don't have these wavelengths in lasers easily available so  still we have problems to really develop color holography. Next slide please. Here is what we  did. This is a familiar Macbeth color target. This is the color target element with three  lasers and here is a color hologram of it. And what we did is account the error in each of these  patches how accurate they can be recording. You can even see going from the real thing using  now digital photography which in itself is not working to reproduce colors well. So then you  go from this to the laser. So the laser we only see this three lasers and you can see here that  the colors are not right. So what we did we calculated each of them and see how well they  can be reproduced theoretically. Next slide please. Here you can see we have three lasers  and here are the errors on each of these patches. They vary depending on some of the wavelengths  are better for this particular color but worse for that and so forth. So we try to get the average  down to the minimum. Next slide please. When we switch to four lasers we have immediately  much better. So the error is down zero zero two not in power error as an average on all these  patches. Next slide. And this is down now with five wavelengths. So there is a dramatic difference  between going between three and four. So any serious application for new seams will require  four lasers for and the four which I just showed you. Next slide here you can see that  all of them on the same slide. So we go from three four and five. So four is a really  and then we'll see if you need to take it in. It depends on the people in the museum that come  and say that this is not the real thing it's a hologram. And if they say that we have not reached  the glory. Next slide. Here is how we do it now. We had three different lasers. A good one for red.  We have a CW nearly a leg laser for the green frequency double and an urban ion laser for 76.  And then we combine them with beam combiners that takes the red send it through and add the green  and add the blue and send both of them. We have a shutter and then we have the so-called  Dennis Yurt setup. When I talk about Dennis Yurt that may not be familiar to people not in  our geography but Dennis Yurt was a person who invented holography in the former USSR  almost simultaneously as anything in the United States. He used what we call the single beam  reflection holograms and that technique is the most suitable for museums because that provide  you with a 180 degree Pw in both dimensions which is a requirement from museums. You don't want to  have a box that you just have to stand in a particular position to see the rainbow away  there and then of course you lose the illusion of having the object and it's gone. So we only work  with the Dennis Yurt technique. And next slide please. Here is our lasers in optic. These are the  two. Drifton and Arvon and the near-linear. We send the beam. This is a laser that may be generated  and then from mind goes into another room and then you see the white beam going into the recording  room. And this is from the laser into the recording room. Next slide please. The reason why we have  separated them is that the lasers are terrible at noise sources with the transformers. We don't want  to have them at all present nor on the table nor in the room where we record holograms. That's  a general rule in holography but even more important when you work with color holograms. You may have  an exposure time of 20 seconds or so. Then you will create vibrations if you don't have an absolute  silent area where you work. And here is that we have a huge table here, a very heavy table  sorted on a German system to stabilize these two lasers so they are floating together in  two different rooms. So an extensive system that works extremely well. The hologram alignment in  or stays over weeks without getting misaligned even when you work on two different tables.  Next slide please. Here is all the equipment we use to measure our holograms with this  spectra-pupram meter here. So you can look at the hologram and measure the colors. Next slide please.  Now we come to the spotlight which has been as I saw very important for color hologram because  when you make the hologram you take the colors you want to achieve is the colors that your  spotlight is going to emit. So you have to set the ratio between your lasers to mimic that.  You can't take the color hologram that you have recorded that and take it out in the sound. Then  they will completely blueish. So the hologram can only be made for a particular spotlight.  That's it. And then they also have to have a specific angle which is exactly the same angle as  you use. Then you recorded it. The spotlight has to be provided of course you have no shrinkage  in the emulsion. And of course shrinkage is out in the color emulsion because then you destroy  the color. So our emulsions have absolutely no shrinkage. Next slide. Here is a commentant  that similar to what we have now. This is a spectrum from background. Mostly they meet in red  as you know it's very little in blue. And the sun of course has much more in blue. So if you want  to make the hologram that works in the sun you have to adjust three wavelengths so they will  match that. Next slide. Then of course something has happened is new LED lights. They are extremely  interesting because now if you get the right wavelengths as we use for recording you can match  that with an LED and all the rest of the light is not illuminating the plan. So that would  give you plates that are much higher contrast because you only illuminate it with a light  that is coming back. Or unfortunately not yet we have such lights that really work well.  There is still a lot of work to be done and also to have done combine these into a white  good light LED. But we are working on it and that is soon we would have such lights that would be  the perfect light source for color holograms. We can have see some of the advantages in the next slide.  Long lifetime. I mean we don't need to walk everywhere and change them. That's another problem  with holograms on display. People ignore to switch the lights if they burn off. They are  holograms in museums. They can be for a year without the light before they say. Here at least  you can guarantee that if you have a hologram on display it will stay live all the time.  Small size improve the sharper images as you have a better spatial piltry. They are very robust.  Heat is generated which is another source in a holographic museum. If you have a light  it gets very hot and you need to have that conditioning. And also so that there are only  advantages that we can develop holographic LED lighting. Next slide please. Here are some examples  of our silver cross emulsion which was done on a consortium in Europe to develop a suitable  image of the color holographic. The possibility of that is some sources of that and mainly from  Russia. Russia for the holography has been well known for the superfine grains since the beginning.  Then it is really needed. Much higher resolution than it needed to do it. So Russia has been the  leader in that. But unfortunately it is very difficult to buy any color material in Russia.  As well it is very difficult to find it anywhere else. Most people like me and  Jean Thierry they don't really deliver emulsion to send it to anybody. So that means that we have  to make our own. But this consortium I was looking into can we commercialize this emulsion and that's  the question. Next slide please. So here you can see the object itself and the hologram of it.  This is a spectrum with the same spotlight that we use to illuminate another object and here is  with this particular point. And then you can see what light is built up with. As of course it's not  identical. If we had a few more here the difference between them would be less and less. But even  now it's very good. I have the holograms here so you can look at them later. And this is the error  in X and Y. So no sorry this is the coordinates. This is the coordinates of the object and this  is the coordinates X, Y and the spectrum of the hologram on Y. Y is of course very difficult  to get perfect in a calder hologram. Next slide. Here is another example I brought. I use this  because it has a lot of blue. Blue is the most difficult calder to record without scatter and  that's why we need nanometer, nanometer, grain size of salt to record that. Our emulsion is in  the order of nanometer measured by the microscope. Next slide please. Here again you can see now  that we are looking in the blue part of the element that we know of course now has a stronger  contribution here in the blue and less in red. You can also see something interesting here.  The wavelengths we use are 647, 532 and 476 and they are identical so there is absolutely no  shrinkage in our plate before and after processing and recording. This is also a must for calder  holography. Next slide please. And displaying as I said that I can only see that the holograms can  be used with fixed installation. There is no way you can put a hologram on a journal or anything  and people will ever see a color hologram. So you have to have fixed installation in museums  and so wall mounted holograms with overhead track lighting and the track lighting should go in the  opposite direction that they should not go along with the wall. They should have tracks for  a perpendicular to the wall for each hologram so you can adjust the angle by moving them back and  forth. So museums need really to rearrange if they want to show holograms. I mean there are  these things with extended lights that you see here. That's okay for small but if you think that you  have a big hologram square meter and you want to extend it's like 10 meters out hanging out from  the frame it doesn't look aesthetically good. So these are things that one has to get away from.  It has to be fixed installation with either integrated lighting in some way or in museums  from the war. As I showed in this museum long time ago the best is to have them tilted  over five and overhead light and hide that light so nobody sees it. That's the most nice way of  showing reflection holograms. Next slide please. And then I want to just say something about  potential application and color application. So this is just to show of course this is art  education I think is one you can say. Every museum in the world every art school in the world could  have a fantastic collection of the most beautiful art pieces for students. They don't have to travel  around the world to see that. They can have this library they go and look at.  Any type of the old artifacts of whatever paintings or sculptures and so on. Next slide please.  Here is an example of cuneiforms I have done for a German museum. And cuneiforms need to be tilted  to read the text. So the photographs of cuneiforms are no good for the people who that's why they  really want to have a color. Color may not be that important for this type of collection or  artifacts but nevertheless we go to the next slide and now you can see the advantage of  holography because when you want to read this text what you do is you hold it in your hand and  retrieve them with the light moving across. So now any person that wanted to study these artifacts  they don't want to send them around to scientists they want to send holograms of them so of this type  so they can read the text and do their research. Next slide please. This is another one I have  brought here and you can see I have all of these holograms that I show if you want to look at them  as holograms. Next slide. This is another thing where you can think maybe for advertising also  that you don't need to have expensive stuff out in airports of course a lot of interest for people  and safety issues so why not just have holograms in these boxes. So can be animated at the  critical meeting. So the important thing to see here is how the reflections really move across  when you go around as if they were actually inside that box.  So this is one of the people that we really amazed when we see things like that they can't believe  that there is nothing behind the glass. Next slide. This is another example of Russian egg which is  again you can see how this point that comes from the spotlight goes on the surface as if that was  how it was hit of the real object. So this really shows the advantage of holographics a dynamic  image as well. This was the lead of the Symbacrosse mansion for the National History Museum in London  and they were very pleased with this type of technique so now museums are really interested  in holographic but there is a long way to go across before we will see that it can be commercialized.  Next slide. Now I talk finally about oil paintings that may not be what to think of because  holographics really do but let's show you what the holographic can do. Next slide. Here is  an original oil painting nothing particular it's a very cheap one but I use that because it was  painted on wood and it has very marked strokes of the brush. So here is a holographic reproduction  only with free lasers so of course the color reproduction is not perfect but it's not that bad  certainly as good as color photography. Next slide. But the advantage for the painters or the  painting in interest is that you can go in the hologram in large areas so you can study in that  hologram of the painting the paint strokes. Also things like this which is in the original of course  you can find here in the hologram identical to that. The reason the color has changed here from  there is not that the color is wrong it's just because you need to tilt the hologram so it goes  out of the correct reference beam which affects the color but then you can see these effects.  So defects are just these particular that of course would be a way to identify a stolen  painting when it comes back. Is this the same painting that was stolen? So insurance company  in the future may require or certainly multi-million paintings should have a holographic reproduction  in the insurance company if something happened. That can also be used to restore the damaged  painting. Next slide. Here is one of my own collection of paintings from Peter van Gravel  1629 to 1790. It's a holographic reproduction and you can also see you know how the light is  showing this structure in the painting. This is on the canvas and we can easily record that as well  just putting the holographic paint on top of the painting. Next slide please. This is the final slide  or almost final but this is what we think holography will do. I had there is something  that you will hear about later. I have now focused on the perfect for pure holographic technique.  There are techniques where we can use computers and photography and combining to holography  which I have a lot of interest in. You will hear more about it from other speakers. I didn't  talk about that because I am mainly interested in holography that can make images that are  identical to the regular work. And these computer and photography since photography is integrated  in the system you can never get it because you have to capture the light as coming from objects  holographically to get something that is identical to the object itself. So the virtual image  behind this type of hologram is today the most interesting image we can get. And also the  extensive field of human about 180 degree in both directions makes it impossible to see that  something is strange within it. And the way from reconstruction of the actual critical  only the light that has scattered off the object during the recording that's why it's so important  to have exactly the right wavelengths and enough of them to make that happen. And as far as I can  see it may happen during my lifetime but definitely in 50 years time I can tell you that holography  will be all over the world of this type of kind. There is no doubt about it. And it's a picture  that the photographic companies today are so they have perfect equipment but they don't look  far enough. They get rid of beautiful recording systems, huge field coatings because the only  material that is silver hang out and also we don't hear there are new materials coming out  there in the photopolymer. So there are a lot of interest in the old type of silver photography  and auction techniques and that will only expand over the coming years. So next slide please.  So as I said people often ask me can you send me a photo of your hologram and say why should I send  that is useless. Why not I can as well send you a photograph of the object itself you already have  it. The only way you can see it is to look at the hologram itself and that's why for those who  have never seen this hologram I have brought all of them here that you have seen so we can look  back there and mean a break. Next slide please. Okay any questions? Yes?  I mean we need to have some coherence aboard that way it goes without saying also that a meter or more.  We talk about here what we do size updates we can do. We need to have at least the coherence to take the depth of this hologram.  So the other thing where lasers have to be absolutely stable output if you set them up and record them  in the meantime the red lasers have changed you can't get white anymore. New changes in the output  from the three lasers will combine into the wrong color. So you have to have the best lasers in the  world which doesn't mean that you have no coherence to do this. Yes? I know that one of the main lines  out of that are the lasers for a certain what's the percentage loss you have to put up with to rate it  come out at four seven six. It is like half. Yes but the 488 is not the new way it's a new  green and it's not good for reproducing white. I won't be able to record for 488 or something  but they have no output enough. There may become new solid state lasers in the future that will have  better colors for color but again they are very hard to get them in the car we need.  Yes?  I'm completely not used to this but is there any danger that the laser which is shot through the objects  might damage the view? No no I mean this is of course it's a very good question if you don't know it.  The amount of laser light hitting them is nothing compared to if you use a flash and take a photograph  of an object you probably need more light to it and the laser lasers are needed over a longer time  during the recording so we may have 20 seconds if you take a flash photograph you in a millisecond  but even if you use pulse lasers which can be used at 20 nanosecond lasers there is no risk because  if there was a risk you would completely burn your emulsion it would completely be destroyed  when you send the light through it so there is no risk to go there everything you need to be  aware of is of course you should test them if there is some very delicate textile that you could  bleach by the immediately pure image that could be the only thing I can think of but I think that  on the mind is in the pyramids they have paintings inside they can't show it to people only can switch  on light occasionally. If you could make green very metallic holograms so then you can make another  cave outside where all these holograms of the wall paintings are put up again and they can be  only at night for years or because the advantage of a hologram it doesn't have any pigment or any  dyes in it so it's a pure physical way of regenerating the light so you can never bleach.  I mean there are things that could happen that's more environmental thing you need to see them  but if you do that they will survive hundreds of years with exactly the same color. The best example  of that is Hickman photography that I mentioned about Hickman who got there I may have to stop now  because we are late so I think we can discuss more things in breaks and so and I think we have to  stop the question because we are late with the problem so thank you very much.  Thank you.
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