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  • You already know that I'm an engineer

  • and I'm really passionate about holography.

  • I believe this will be the technology of the future,

  • and I would love to talk a little bit more about it.

  • When people hear what I do,

  • they usually ask me about Tupac's hologram

  • and I'm really sorry to tell you that this is just an optical illusion,

  • which has nothing to do with true holography.

  • The way it works

  • is that you have a thin sheet of glass that both transmits and reflects light,

  • so when you look into it you see the people standing behind it,

  • as well as Tupac's reflection.

  • I mostly know holography from reading,

  • research papers, PhD dissertations

  • and in fact, I wanted to know a bit more about it.

  • So I made a Google searchthe most popular thing I guess.

  • And I was shocked to realized

  • that a lot of people who claim

  • that they developed a novel holographic technology

  • were not making holography in the scientific sense.

  • Of course these technologies exist and they are quite impressive,

  • but, for instance, a 3D display

  • is just a 2D image projected onto a cylindrical surface.

  • As you walk around, you have the impression

  • that you are seeing a person from different perspectives

  • but is nonetheless a 2D image.

  • So what is holography?

  • I like to think about holography as playing with light.

  • And you probably heard somewhere that light is a wave.

  • What does it mean for us?

  • I like to imagine the situation by looking at water waves.

  • As you make a ripple,

  • it travels outwards in a circular manner,

  • if you make two ripples at the same time,

  • you can see

  • that these two waves overlap and form a certain pattern.

  • You will soon realize

  • that there will be some places

  • where water doesn't seem to move at all.

  • And in some places we have a large oscillation.

  • A few words for clarification,

  • water waves are quite big and easy to see,

  • however, light is a very small wave,

  • is as small as one hundredth of a human hair,

  • and it oscillates very, very fast,

  • as fast as 500 billion times [per second].

  • What does this have to do with holography?

  • Imagine that you have an array

  • 1,000 X 1,000 of small slits

  • and you can open and closed them in any way you want.

  • What you can see on the screen

  • is a sample hologram which is just an array of black and white squares.

  • Black means a closed slit and white an open one,

  • Each open slit will create a new small wave

  • and since there's loads of these waves

  • they will overlap in some way

  • and form a pattern on the screen.

  • What we are doing here is we're telling light

  • that it should appear in certain places but not in others.

  • I should say a few words about the hologram generation.

  • As you can guess it's a pretty complex operation,

  • and in fact, about ten years ago,

  • you would need a supercomputer to do the calculation

  • within a reasonable time frame.

  • Now you probably don't realize,

  • but most of you have a super computer at home.

  • And it's called a graphic card.

  • Graphic cards can do operations much faster than processors

  • and do them all in parallel.

  • We said something about hologramshow we generate them

  • now I'm going to tell you how we display them.

  • First of all you need a source of light which is laser.

  • That laser beam illuminates the micro display

  • and later on we project the image onto the surface,

  • The angle view depends on the type of lens you use,

  • and in fact in my research, we use a simple ball of glass,

  • that gives us a very wide angle

  • but produces a lot of blur in the image.

  • What is blur?

  • This is the ideal image,

  • and I'm going to show you two types of blur,

  • one of them is called defocus;

  • for instance, it happens

  • when the lens is slightly misplaced from its position

  • and the other type of blur is called coma

  • and the name comes from the fact

  • that the point seems to have a tail like a comet.

  • But as I have already said,

  • in holography, we design the wave,

  • we tell light how it should behave

  • and in fact we can correct that.

  • In order to do that

  • we use special functions called Zernike Polynomials,

  • and to correct the defocus aberration,

  • we use a Third Zernike Polynomial which looks like that.

  • In fact, every single aberration

  • has a Zernike Polynomial associated with it that corrects it.

  • We need to know an odd proportion to combine the aberrations,

  • and the way I approached the problem is,

  • I used the webcam

  • in order to measure the aberrations.

  • Let's have a look at the results.

  • What you should see here is a grid of points,

  • and as you can see this is quite bad.

  • In the corrected image, in fact most of the points are small and circular.

  • Next one is a page of a text and if you try to read this,

  • you'd probably have a hard time.

  • But in the corrected version,

  • most of the text can be read.

  • Let's proceed to 3D holography

  • and wonder what makes us see things.

  • Imagine you see the tiger,

  • you see it because the sun illuminated it

  • and the scattered rays somehow ended up in your eyes.

  • Imagine we are able to reproduce

  • the same set of rays

  • that the real object would produce.

  • And in that case, you would see a three dimensional tiger

  • behind the display.

  • Now, when I was younger,

  • I was interested in computer graphics and programming,

  • and this added definition

  • is slightly closer to my heart.

  • What you should see here is

  • you take every single point in the image

  • and you focus it at different distances

  • and that's precisely how you create a 3D hologram.

  • How does it look like?

  • At this point I was focusing the camera at different depths,

  • and you can see how different parts of the image

  • go in and out of focus.

  • I have another

  • whoops, sorry! —

  • So, what you should see here

  • is that we have different letters at different distances;

  • it should read TEDxWarsaw.

  • This is the experimental set up

  • where we viewed the hologram.

  • With a source of light, which is a laser diode,

  • two lenses expand the beam,

  • and as you look into the micro display,

  • you see a three dimensional object.

  • OK, I'm afraid the video didn't really work, but

  • what you can see here

  • is that we were moving our viewpoint

  • and in fact, this situation is somehow similar

  • to approaching a platform [while] on a train.

  • The platform itself moves very, very fast,

  • the trees, some distance away, move by a small amount,

  • and the sun in the sky doesn't seem to move at all.

  • And that is precisely what is happening here.

  • You've seen some basic properties of 3D holograms.

  • However, these holograms were pretty simple,

  • and at this point I'm going to show you

  • what a lot of resources and computer power can do.

  • This system can display a 3D image

  • that is 14 centimeters in size

  • and does that in real time,

  • meaning 30 times a second.

  • However, the system is pretty expensive

  • and requires a lot of computers in order to produce the image.

  • However, researchers all over the world

  • are working in order to shrink the system,

  • improve the image quality

  • and make it available for everyone.

You already know that I'm an engineer

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TEDx】3Dホログラフィ|Andrzej Kaczorowski|TEDxWarsaw (【TEDx】3D holography | Andrzej Kaczorowski | TEDxWarsaw)

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    richardwang に公開 2021 年 01 月 14 日
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