60 symbols Video.

I'm gonna invite you Brady to come to the toilet with me.

Do so we're gonna talk about three D movies.

And how do three D movies and three D glasses work?

What's the technology behind these things?

I want to see Hugo, which is a wonderful, wonderful film before Christmas with my daughters.

So how does it work?

Well, it's based around what the first question go ask is, Well, why do we have depth perception?

How do we have in the real world?

We get some sense off Brady so far away from me?

I can sort of see that he's a solid object rather than a plan.

Where do we get that from?

The key thing is, we've got a physical to ace, and they're separated by a certain distance.

So both of these I see a slightly different scene on your brain is unbelievably clever, taking those different scenes on bringing them together and giving you that depth perception.

So the question then is how do you get something that's flat on a screen in a cinema or on a television and give you that depth perception.

Well again, What you need to do is to have those.

You're playing different scenes to different eyes.

That's the key thing.

But what you do is you have two cameras when you're filming the movie.

One camera is filming workers to the left.

I want cameras filming what goes to the right.

Andi, You bring those together and you have a slight offset.

Which is why when you take your glasses off, everything looks quite blurred on the screen.

So the challenge that the cinema is well, how do you take something on a flat screen?

And how do you deliver those two separate scenes each toe?

One I How did you get the dirty trick the brain into thinking that scene is not really depth on dhe.

Do we do that?

Well, it used to be you.

Me?

Remember, some of the slightly older viewers might remember that you used to have red and blue glasses.

You have these 10 2 things, and in the eighties I think it tickles all the way back to maybe the forties.

I could be wrong there, but I think that that sort of red and blue approach hards being around a long time.

And what are they doing there?

What they do is they basically have red and blue filters.

They take the the film that one cameras shot on the Take, a film that the other cameras shot, one of which has a blue 10 theater, which is a red tint on.

Then they use blue and red filters to separate those out.

So the one that's got the red tent will come to the the red eye as it were, the ones with the blue team record of the Blue I Yeah, we've moved on, and the problem with red and blue offices that you're playing with the colors you're losing color definition.

They look washed out.

The depth perception isn't as good, actually, with the colors on dhe.

It's very problematic in terms off getting a nice high definition movie.

So what do we do now?

Well, actually, what we do is we play with something called the Polarization of Light.

You've come across polarization.

You've come across Polaroid before, and Polaroid is basically a thin film.

I've got some of it here and in that thin film are lots and lots off polymer molecule, long chain molecules that are stretched in a particular direction.

And so I'm sure you've seen this before.

Who?

Take a piece of problem or enforcement?

It's a bit.

I've just broken it.

We'll do it this way.

You take a piece of off Polaroid film, you match them up like that, you can roughly see tribute, I guess.

And then when you turn it together, turn it, turn it round 3 90 degrees.

It blocks the light.

Why does it do that?

Okay, so we've got to go back.

I'm afraid to Undergraduate physics A level physics, high school physics.

This is gonna be tricky to explain at, ah, non scientific level.

But lights or wave, let's start without all the times that behaves like particles.

For the purposes of this, we're gonna take that lighters with so light is a wave.

What is it?

A wave off?

Well, it's what it is is electromagnetic wave.

It's an electric field on a magnetic field.

We're gonna concentrate here only in the electric field, cause that's all really that matters.

So this thing lights propagating like that in that direction.

Now it's got we call it an electric field ve actor on what that basically is, is tells us which direction the electric fields pointing.

So in this case, it's propagating that when the electric fields pointing that where we turn it around like that, it's propagating now when the electric fields pointing that way turn around like that, the electric fields pointed that way.

Of course, this is going back and forth gazillions of times a second.

To use a technical term.

That's only really need to know you've got this this characteristic off the wave, which tells you basically in which planets vibrating.

So what the Polaroid does is when you've got, you know, the lights, you got all that that that the light that's in this room and that light is basically own polarized, right?

That means that that that it's it's got some light waves which are like that so much I like that so much.

I like that so much like that.

All right, friends of different organizations.

So all the lightness one wasn't, uh or random, but it was actually going in one direction.

Then what you have is, if you're lying, you're Polaroid in the direction off the east off the electric field.

Um, Then what you find is that they're like and get through very simply.

However, if you rotate it round just like I did with the Polaroid before them, it doesn't get through.

And that's a very, very useful property of light of certain materials like Polaroid.

So what?

I want to see Hugo.

What?

What happens is that you use these glasses.

So in one side, the simplest version of these is that on one side we have a Polaroid, basically, which is a line like this on the other side with a polarizer Polaroid film which is aligned like this.

So what happens is that you take those two, uh, different versions off the movie which are filled with different cameras, and you polarize.

You put a polarizer in for each one of those cameras as it where, and that means that the light coming from the screen associated with the left I see is polarized this way on the late coming from the screen associate with right, a is polarized this way.

And then you put these on.

And now bingo.

You've got a way of differentiating distinguishing between what should be going to the left eight on what should be going to the right.

That's very clever.

You're watching two moves and once with slightly different scenes, and then you are using the polarization of the light coming from the screen.

T trick your brain into thinking Well, okay, What I'm seeing here is real life, and therefore it must have a depth.

I told a little fib.

It isn't really linear polarization here.

What we actually have with these glasses and many of these glasses is something called circular polarization.

There, instead of this electric field being in the plan like this, it rotate around.

So it's rotating like this or in the other direction.

It can be rotating like this on.

We call that left and right circular Lee polarized light because if you look, if you imagine my fingers going like this, it's traveling for.

But if you just look in this plan, where you see is a circle not circumcised going like that or it's going like that.

So the tip we described in terms of of actor, an electric field factor which will tear around that would have looked so good if we were filming in three days.

Oh, it would have looked really good.

But it's the same.

It's the same principle to you Could have left and right.

Circular Lee Polarized.

Like you might argue.

But what does this now look like?

So So what?

That will you?

It's getting tricky, Brady, because what you have to do to convert circuit, what you do is you take that circular Lee polarized light on you.

Convert it to linear polarized light on.

Then you use the same approach.

Where does the conversion conversion happens here?

You've basically got within the glasses you've got you got the polarizer.

But you've also got something that converts that sits Circular Lee polarized like, too linearly polarised light.

So why I don't like what?

Because for various reasons, I'm not gonna go into him unless we want to make an hour long video.

Uh, there's various advantages to having circular Lee polarized light in terms off the ability to move your head around to keep the depth while you have your head of different angles which you don't get from the new polarizer.

But these are really amazing it I'm gonna do something that I've never done before.

60 symbols video.

I'm gonna invite you Brady to come to the toilet with me.

I've told you that circular polarization.

Now one of the remarkable things with MERS is that Murmur will convert right Circular Lee polarized light.

So, like that's going to say this direction into the other direction.

So when it will not light, which is polarized in the particular handedness, as we call it right or left hits the mirror, it gets converted from right handed left handed.

That's really amazing, because now when we look at these and I advise you to do this at home, it's really quite quite neat.

And I'll certainly be bringing these home and doing it with Sean into my daughter's this evening.

You put it in front of the mirror and what you can see is that as you go from this eye to this, I that it appears black so looking down through it and see so on this case Now, the one on the left is black.

One on the right.

You can see true, we know.

Move over to this one.

One on the right is black and the other one you can see through what the hell is going on?

They're So the light is coming from all the lights in here.

It's bunching off my face and it's striking the mirror and then it's coming back and hitting me.

So what's happening here is that the light comes down, strikes my fears, bounces off my face goes true.

This thing right?

No nous ily All that light is randomly polarized, right and left circular Lee polarized however, remember this thing access of filter.

So it it makes sure that only late with a particular polarization steak and get through this is where it gets really clever.

So it comes true.

God's true here that light has got a particular polarization state, which this one has let true.

Let's say right 100 strikes the murmur.

The murder changes its polarization.

So it comes back and oh dear, I can't get through because I've now got the opposite polarization state, which is really quite clever.

So it's a really nice example off.

Well, you can look into is classical physics, quantum physics, but quantum physics at the movies.

Basically, it's a really, really clever example off polarization, I think on blown away by this type of technology.

It's it's really quite need.

We could perhaps go into treaty television, but that's a different type of technology, which maybe we'll leave to another day.