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<i>preroll music</i>

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Herald: Our next speaker has studied in Bielefeld,

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and he studied... <i>laughter</i><i>clapping</i>

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what he did is: He studied laser physics.

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And now he is working at the Max Planck Institute
for extraterrestrial physics.

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And today he will explain you

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how it is possible to use laser light

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to enhance distorted images

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that were take from the earth

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of stars and galaxies and nebulars.

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So I want to hear a

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really loud and warm applaus

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for Peter Buschkamp with

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"Shooting lasers into space -

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For science"! <i>applause</i>

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All right! Thank you for the nice introduction

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Thank you, for coming here

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this evening.

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I'm very excited

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to speak at the conference.

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Finally I find a talk

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where I can contribute

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after all those years.

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I'm not going to talk about Bielefeld.

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You might want to hear something about that.

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I'm not allowed to tell you... right?

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Okay, so today I'm going to talk about

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a bit what is in my field

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of experties.

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If there is one thing

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I want to bring across to you

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then it is

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It's not about a single person

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showing this to you this evening.

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This is a team effort and a real team effort.

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So most of the images are done by

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a college of mine Julian Ziegeleder.

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And the PI of the project,

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so the leader of the project

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Sebastian Rabien

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has contributed some slides.

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And I wouldn't be standing here today

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and showing you these images

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if it wasn't for a huge team

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and many people.

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I hope this is reasonably complete,

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but I think there were even more.

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Many people have tributed most and

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long years of there career into such a project.

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So this is never about something

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which a single person does

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and he or she finds something very cool

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and then saves the world.

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No, it's always a big, big team!

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But before we actually see the lasers

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then in working, we have of course to clarify

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why we do this.

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This is not just because we can.

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We can! But there is a reason for that,

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because if you want to get funding,

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you have to write a reason and a reasonable
reason.

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Not just because "We want to!"

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So in the first part

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I will introduce you

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to the whole thing

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and we talk about bit... about the problem

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which we want to tackle

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with this kind of technique.

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I will mostly present only diagrams

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not actual hardware blocks or relays.

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So you get the basic concept.

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So when we do astronomy

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we do two types of things.

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We either do imaging,

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which is: We maybe produce a nice image

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of a star - so that's the blop over there -

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or we take this image,

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maybe this little blop over there,

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and make it into a spectrum,

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so disperse the light,

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and then we look at the differential intensity

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between the diverse colors

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or are there maybe

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- for example you see black lines in there -

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absorption bands and so on.

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To do such a thing you need a spectrograph

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and in a spectrograph

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there is a thing called an entrance slit.

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So this slit you have to

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put over your objects,

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so you don't get light from left or right next to the object

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to what you want to observe or analyse

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so that you only get light from where you
wanted.

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The thing is now

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this slit can not be made

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arbitrarily wide or small,

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because the width of the slit directly

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determines what kind of resolution

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you have in such a spectrometer.

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as it's called. This is a quantity

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Which needs to be above a certain value

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when you want to do certain kinds of analyses.

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So it has fixed width.

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So now if we look at an image produced

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of one of the most capable telescopes

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on this planet

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and we put a representation for this slit

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over the star

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- okay now its white, let's make this black -

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then you see if you want to go

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for that star over there,

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you do have a problem already.

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As said, you can't make this slit wider,

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but the star is actually larger than the slit,

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meaning that you lose light.

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"Well you lose some light...." No!

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If you want to quantitative measurements

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you want to have all the lights

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and all the pixels.

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So you can't get rid of them

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and just throwing something away.

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So, but our image is looking like that.

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It's maybe nice, so but can we do better?

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Yes, we can!

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And this is what we can achieve with

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adaptive optics.

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This is an image that has been produce

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with adaptive optics with a

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LASER AO assisted system.

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And if I flip back and forth you see

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there is a difference!

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All right! So why is that?

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Why don't we get this ideal images?

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The reason is because there is the atmosphere.

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The atmosphere is great for breathing.

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It's not that great for astronomy.

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So if you have a star up there somewhere

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in outer space

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- can be very far away - so the photon

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have travelled for 11 Billion years

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and now they finally hit the atmosphere

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and then something happens

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which you do not want.

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Okay, first they travel freely.

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There is a nice planar wavefront.

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So it's not disturbed by anything,

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maybe something but that's not the

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scope of this evening. It's planar, it's nice!

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And if you actually have a satellite,

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it's very cool.

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Because then you can directly record this

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undisturbed light.

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If you have something on the ground,

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well, you do get a problem,

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because the atmosphere introduces turbulence,

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because, well, the air wobbles a bit.

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There are stream coming from all directions.

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There are temperature gradients in there.

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And these all work together

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and make from this nice planar wave front

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a crumbled one.

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If you have a perfect image

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which you create

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- This is called "diffraction limit".

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This is just limited by the size

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of your optics.

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So the wider your optics is,

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the nicer your resolution is of your image.

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If you then build a large facility with

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maybe two 8 meter mirrors on the ground,

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well, you only get your seeing limited image.

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Seeing limited. The Seeing is this wobbling

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of the atmosphere as it's called.

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And that's about it.

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You can make it arbitrarily large.

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You won't get a better resolution

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then a backyard telescope

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of having 20cm in diameter.

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So yeah...

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What to do?

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There have been people, of course,

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thinking about this problem longer.

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And the first idea came up in 1953.

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And some guy Palomar Observatory

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in California said: "Well, if we have

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the means of continuously measuring

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the deviation of rays from all parts

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of the mirror and amplifying and feedback

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this information so as to correct locally

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the figure of the mirror

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in response to schlieren pattern,

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we could expect to compensate both

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for the seeing and for the inherent imperfections

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in the optical figure."

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Ehhh... what?

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So if we could somehow get rid of this wobbling

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or conteract that,

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then we could get this perfect

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diffraction limited imaging we get in space

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also on the ground.

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In the 1970s the US military started

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to experiment on that.

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Well, I guess the Russians too,

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but it's not... it's known that the US started

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at Starfire Optical Range.

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In 1982 they build the first AO system,

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adaptive optics system.

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The "Compensated Imaging System" on Hawaii.

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And in the late 80s the first astronomical
use,

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adaptive optics system "COME-ON"

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as it was called was installed at the

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Observatoire Haute-Provence

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and at ESO at La Silla.

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That's the European Space Observatory.

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All right so that was:

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Yeah, we get for we found that this

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fussy blob is actually not a fussy blob,

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but two fussy blobs.

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<i>laughter</i>

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Well it's a binary system as I would say

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if this was at an astronomical conference.

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But yeah, you disentangle things

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you could not see before.

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Okay! How does this AO system look like in
principle?

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So again we have this star somewhere,

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we've learned already that

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we do have... - actually you see this slight

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schlieren pattern in the air

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for the warm and the exhaust from the...

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Yes, there is a bit flimmering in the background.

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That's seeing. Okay?

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So the image is not as sharp here as

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it comes from the projector.

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Okay, that comes from somewhere

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and then we need a system

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which has three components.

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One is a deformable mirror,

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the other is a wave front sensor

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and the third one is a real time computer.

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We need something to actually measure

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what is going on.

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Then we need to take this measurement

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and extract some information from

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this measurement

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and then we need something

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which can correct this wave front,

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straighten it out so to speak,

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'cause we want to have it straight again.

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So the wave front sensor sends some information

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to the real time computer.

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This some information namely is:

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What is the curvature?

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How does this wiggled thingy look like?

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- The wavefront -

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And that real time computer computes

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then information that goes

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to the deformable mirror

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and that in real time shaped

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in an arbitrary shape

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conteracting that incoming wave front

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and then straightening it out.

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So we do have a light path like this.

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First it goes on the deformable mirror,

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goes on something else,

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which I will come to in a minute,

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and then this wave front sensor.

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And of course this means if you run it

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you do have a control loop,

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meaning measure something here,

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the wavefront,

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you put the information into there feeding

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that into the deformable mirror,

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that deforms somehow,

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modifies this wave front that comes

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from above and then of course

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you want to have a feedback loop:

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Is that what I did enough?

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Do I have to do more?

279
00:11:31,250 --> 00:11:35,240
And also: Of course in the next second

280
00:11:35,240 --> 00:11:36,920
or split second this pattern

281
00:11:36,920 --> 00:11:38,020
will have changed,

282
00:11:38,020 --> 00:11:39,420
because the atmosphere is dynamic.

283
00:11:39,420 --> 00:11:41,240
If it wasn't dynamic we don't need

284
00:11:41,240 --> 00:11:42,480
to do this in real time,

285
00:11:42,480 --> 00:11:44,050
but we have to do it in real time.

286
00:11:44,050 --> 00:11:46,420
Real time meaning we have to do this correction

287
00:11:46,420 --> 00:11:50,080
and calculation and sensing at a rate of

288
00:11:50,080 --> 00:11:54,390
about 1 kHz, so a 1000 times a second.

289
00:11:54,390 --> 00:11:55,600
Then we have a scientific instrument

290
00:11:55,600 --> 00:11:58,650
because actually we do want to see

291
00:11:58,650 --> 00:11:59,440
what is in there.

292
00:11:59,440 --> 00:12:00,680
And so this thing in the middle

293
00:12:00,680 --> 00:12:02,440
is a beam splitter.

294
00:12:02,440 --> 00:12:03,830
It takes some of the light,

295
00:12:03,830 --> 00:12:04,899
puts it to the wave front sensor

296
00:12:04,899 --> 00:12:07,420
not all, because most of it should go into

297
00:12:07,420 --> 00:12:08,800
the scientific instrument

298
00:12:08,800 --> 00:12:10,540
and there, as you see here,

299
00:12:10,540 --> 00:12:12,080
then the wave front is straightened out

300
00:12:12,080 --> 00:12:13,950
again and then I can focus it

301
00:12:13,950 --> 00:12:17,430
into my instrument.

302
00:12:17,430 --> 00:12:18,839
To do actually that

303
00:12:18,839 --> 00:12:19,550
I have to do...

304
00:12:19,550 --> 00:12:21,630
- This is the one slide in this talk

305
00:12:21,630 --> 00:12:26,539
with a Greek symbol -

306
00:12:26,539 --> 00:12:30,510
You have to this incoming wave front

307
00:12:30,510 --> 00:12:31,950
which is shown in orange

308
00:12:31,950 --> 00:12:33,960
and then you do a piecewise linear fit

309
00:12:33,960 --> 00:12:35,649
which is an approximation

310
00:12:35,649 --> 00:12:36,690
of the slope.

311
00:12:36,690 --> 00:12:38,390
Of it actually how it looks like.

312
00:12:38,390 --> 00:12:43,380
It's put into linear pieces.

313
00:12:43,380 --> 00:12:46,010
And the size of what is normally

314
00:12:46,010 --> 00:12:49,320
can be taken als a linear fit

315
00:12:49,320 --> 00:12:51,860
Piece is roughly 10 - 15 cm

316
00:12:51,860 --> 00:12:53,600
for good observation sites

317
00:12:53,600 --> 00:12:55,290
while this thingy here

318
00:12:55,290 --> 00:12:57,649
so this is the primary mirror of the telescope

319
00:12:57,649 --> 00:12:58,860
which collects all the light

320
00:12:58,860 --> 00:13:01,310
that comes from outer space

321
00:13:01,310 --> 00:13:04,339
is usually for the big telescopes

322
00:13:04,339 --> 00:13:06,990
at this point 8 to 10 meters

323
00:13:06,990 --> 00:13:13,730
Okay, but how do we get this slope?

324
00:13:13,730 --> 00:13:15,980
Now we know that we can approximate it

325
00:13:15,980 --> 00:13:18,000
in pieces, but how do we get

326
00:13:18,000 --> 00:13:19,960
the slope?

327
00:13:19,960 --> 00:13:22,140
Because we need theses slopes of course

328
00:13:22,140 --> 00:13:25,220
fed into this deformable mirror

329
00:13:25,220 --> 00:13:25,710
to maybe okay:

330
00:13:25,710 --> 00:13:27,560
If it comes like this, I go like this

331
00:13:27,560 --> 00:13:29,620
and it comes in nicely

332
00:13:29,620 --> 00:13:30,960
or comes out nicely.

333
00:13:30,960 --> 00:13:33,649
So is where the sensor comes in.

334
00:13:33,649 --> 00:13:36,290
There are different types of these sensors,

335
00:13:36,290 --> 00:13:37,470
but the one we are using

336
00:13:37,470 --> 00:13:40,910
is a so called Shack-Hartmann-Sensor.

337
00:13:40,910 --> 00:13:43,640
And it looks like this.

338
00:13:43,640 --> 00:13:45,850
We have... this is the ideal case of course.

339
00:13:45,850 --> 00:13:48,060
So we have an incoming planar wave front

340
00:13:48,060 --> 00:13:49,560
- straight on.

341
00:13:49,560 --> 00:13:51,690
And we do have an array of lenses,

342
00:13:51,690 --> 00:13:57,020
so it's just 1.. 2.. 3.. 4.. lenses

343
00:13:57,020 --> 00:14:00,050
and then in an array like 4 by 4.

344
00:14:00,050 --> 00:14:02,300
And they all focus what is coming in

345
00:14:02,300 --> 00:14:05,500
into onto a detector and this wave front

346
00:14:05,500 --> 00:14:07,350
that is coming in is planar

347
00:14:07,350 --> 00:14:09,220
like this on the left.

348
00:14:09,220 --> 00:14:11,709
Then you do get a regular spaced grid

349
00:14:11,709 --> 00:14:15,420
of focus points, in this case 4 times 4

350
00:14:15,420 --> 00:14:17,630
so 16.

351
00:14:17,630 --> 00:14:19,430
If now this incoming wave front

352
00:14:19,430 --> 00:14:24,399
is no planar it looks like this.

353
00:14:24,399 --> 00:14:26,970
So the focus points do move a bit,

354
00:14:26,970 --> 00:14:28,670
because, well, it came in like this,

355
00:14:28,670 --> 00:14:29,959
so the focus is offset.

356
00:14:29,959 --> 00:14:33,730
I will flip it back and forth again.

357
00:14:33,730 --> 00:14:36,540
So it's looking like this and you see

358
00:14:36,540 --> 00:14:39,240
of course you do know what is perfect

359
00:14:39,240 --> 00:14:43,100
meaning they are
at their designated grid points.

360
00:14:43,100 --> 00:14:47,480
If its imperfect, well, then just measure

361
00:14:47,480 --> 00:14:50,450
the deviation from their zero position

362
00:14:50,450 --> 00:14:51,270
so to speak

363
00:14:51,270 --> 00:14:55,720
and then you do have a proxy for the slope.

364
00:14:55,720 --> 00:14:57,570
Of course it's a bit more complicated
than that.

365
00:14:57,570 --> 00:15:00,300
There are matrices involved which are not

366
00:15:00,300 --> 00:15:04,790
necessarily in a square form

367
00:15:04,790 --> 00:15:05,890
and you have to invert them

368
00:15:05,890 --> 00:15:10,970
and if you don't... yeah... ...

369
00:15:10,970 --> 00:15:12,660
There are pretty clever people

370
00:15:12,660 --> 00:15:15,610
and programmers working on this type of

371
00:15:15,610 --> 00:15:16,870
problems.

372
00:15:16,870 --> 00:15:19,030
And this is actual current research.

373
00:15:19,030 --> 00:15:23,650
This is far from done, this field.

374
00:15:23,650 --> 00:15:27,520
Okay, so suppose we do have the slopes.

375
00:15:27,520 --> 00:15:29,430
Then we take a deformable mirror

376
00:15:29,430 --> 00:15:32,580
and this is the zeros order approximation

377
00:15:32,580 --> 00:15:33,950
of a deformable mirror.

378
00:15:33,950 --> 00:15:35,640
Let's say the wave front looks like that,

379
00:15:35,640 --> 00:15:37,630
well, then take just a mirror which is

380
00:15:37,630 --> 00:15:39,649
maybe reset a bit in the middle

381
00:15:39,649 --> 00:15:41,470
the other tipped forward.

382
00:15:41,470 --> 00:15:43,450
It bounces on this mirror

383
00:15:43,450 --> 00:15:45,820
and because there is something sticking out there

384
00:15:45,820 --> 00:15:46,680
and in there

385
00:15:46,680 --> 00:15:49,430
well if this approaches there goes back

386
00:15:49,430 --> 00:15:50,790
and in the end the whole thing

387
00:15:50,790 --> 00:15:54,510
when it has been reflected is planar again.

388
00:15:54,510 --> 00:15:57,170
Okay, that as said,

389
00:15:57,170 --> 00:15:58,910
that is the easiest order approximation

390
00:15:58,910 --> 00:16:01,029
for that. It's a bit more complicated.

391
00:16:01,029 --> 00:16:03,930
Your incoming wave front doesn't look like that

392
00:16:03,930 --> 00:16:08,680
It's normally a bit more complex.

393
00:16:08,680 --> 00:16:10,850
And that means you do have to have

394
00:16:10,850 --> 00:16:17,170
more wobbling in your deformable mirror.

395
00:16:17,170 --> 00:16:18,279
You could do this.

396
00:16:18,279 --> 00:16:21,399
That's in the upper diagram.

397
00:16:21,399 --> 00:16:22,899
You could do this with a membran

398
00:16:22,899 --> 00:16:24,200
which is continues

399
00:16:24,200 --> 00:16:27,730
or maybe it's also in pieces

400
00:16:27,730 --> 00:16:29,580
and this segments are driven up and down

401
00:16:29,580 --> 00:16:32,450
or maybe tilted by piezo stages

402
00:16:32,450 --> 00:16:35,140
that are put underneath.

403
00:16:35,140 --> 00:16:36,540
Remember they have to do like

404
00:16:36,540 --> 00:16:38,759
a thousand times a second

405
00:16:38,759 --> 00:16:40,220
or you could do something like

406
00:16:40,220 --> 00:16:43,720
you take a two piezo electric wafers

407
00:16:43,720 --> 00:16:45,399
they have opposite polarizations

408
00:16:45,399 --> 00:16:47,110
put electrodes inbetween

409
00:16:47,110 --> 00:16:49,060
and then when you apply a voltage to this blue

410
00:16:49,060 --> 00:16:51,350
electrodes then you have local bending.

411
00:16:51,350 --> 00:16:52,950
So the one thing will bend up,

412
00:16:52,950 --> 00:16:55,990
the other ones will bend in the opposite direction.

413
00:16:55,990 --> 00:16:58,080
And then you do have changing curvature

414
00:16:58,080 --> 00:17:00,560
on this whole thing.

415
00:17:00,560 --> 00:17:04,260
It's not that easy of course in reality,

416
00:17:04,260 --> 00:17:07,510
because they are not completely independent

417
00:17:07,510 --> 00:17:09,429
one cell will influence the other

418
00:17:09,429 --> 00:17:11,519
and yes...

419
00:17:11,519 --> 00:17:14,320
But this is the basic principle.

420
00:17:14,320 --> 00:17:18,369
Okay, now you have seen

421
00:17:18,369 --> 00:17:19,970
there was this beam splitter.

422
00:17:19,970 --> 00:17:22,150
So most of the thing goes into the

423
00:17:22,150 --> 00:17:23,099
science instrument

424
00:17:23,099 --> 00:17:26,270
and some goes to our wave front sensor

425
00:17:26,270 --> 00:17:27,760
of the light.

426
00:17:27,760 --> 00:17:30,549
If the object we want to record like

427
00:17:30,549 --> 00:17:34,670
a galaxy that is 11 Billion lightyears away

428
00:17:34,670 --> 00:17:36,190
then this galaxy is to faint.

429
00:17:36,190 --> 00:17:38,860
We can't analyse it's light.

430
00:17:38,860 --> 00:17:41,140
So what do we do?

431
00:17:41,140 --> 00:17:43,230
We need maybe a star that is nearby.

432
00:17:43,230 --> 00:17:45,030
So our galaxy, which we actually do want

433
00:17:45,030 --> 00:17:47,160
to observe, is the red thingy

434
00:17:47,160 --> 00:17:49,030
the bright star is the yellow one

435
00:17:49,030 --> 00:17:50,789
and if there are reasonably close together

436
00:17:50,789 --> 00:17:52,500
- reasonably close meaning

437
00:17:52,500 --> 00:17:56,280
about 10-20 arcseconds.

438
00:17:56,280 --> 00:17:58,350
If you stretch your arm and look at

439
00:17:58,350 --> 00:18:01,750
your little finger at the finger nail,

440
00:18:01,750 --> 00:18:06,120
this is about 30 arcminutes.

441
00:18:06,120 --> 00:18:08,950
1 arcminute has 60 arcseconds so it's

442
00:18:08,950 --> 00:18:09,900
very close!

443
00:18:09,900 --> 00:18:11,080
It's not like the galaxy is there

444
00:18:11,080 --> 00:18:13,500
and the star is there. No!

445
00:18:13,500 --> 00:18:15,550
It's there!

446
00:18:15,550 --> 00:18:18,460
Because if you have a large separation

447
00:18:18,460 --> 00:18:22,140
then they do sense different turbulence.

448
00:18:22,140 --> 00:18:27,330
Simple as that.

449
00:18:27,330 --> 00:18:28,530
Now the thing is

450
00:18:28,530 --> 00:18:31,080
that less than 10% of the objects

451
00:18:31,080 --> 00:18:31,660
you have on sky

452
00:18:31,660 --> 00:18:33,110
which you are normally interested

453
00:18:33,110 --> 00:18:36,390
do have a sufficiently close and bright star

454
00:18:36,390 --> 00:18:37,160
nearby.

455
00:18:37,160 --> 00:18:38,230
So what to do?

456
00:18:38,230 --> 00:18:45,290
And now we come to the lasers.
<i>laughter</i>

457
00:18:45,290 --> 00:18:48,270
Because if don't have your....

458
00:18:48,270 --> 00:18:49,750
If the don't wanna play nicely

459
00:18:49,750 --> 00:18:54,750
build your own themepark with yes ... you know.

460
00:18:54,750 --> 00:18:57,929
So make your own star!

461
00:18:57,929 --> 00:18:59,610
This is what we do.

462
00:18:59,610 --> 00:19:02,680
Because if the star is not nearby,

463
00:19:02,680 --> 00:19:04,799
a sufficiently bright one,

464
00:19:04,799 --> 00:19:07,830
well, why has it to be sufficiently bright?

465
00:19:07,830 --> 00:19:09,620
Because if you want to do this computation

466
00:19:09,620 --> 00:19:12,120
a thousand times a second, well,

467
00:19:12,120 --> 00:19:19,470
then the time for your CCD
when you record this image

468
00:19:19,470 --> 00:19:23,820
for your wavefront is a thousands of a second.

469
00:19:23,820 --> 00:19:25,280
And if you don't have enough photons

470
00:19:25,280 --> 00:19:26,799
in a thousands of a second, well,

471
00:19:26,799 --> 00:19:29,299
then there is no computation of this offset

472
00:19:29,299 --> 00:19:31,640
of this little green dots on that grid.

473
00:19:31,640 --> 00:19:33,490
So you need a lot of photons.

474
00:19:33,490 --> 00:19:36,549
So let's get enough photons!

475
00:19:36,549 --> 00:19:37,580
And there are actually two things

476
00:19:37,580 --> 00:19:38,799
what you can do.

477
00:19:38,799 --> 00:19:42,480
There is a conveniently placed sodium layer

478
00:19:42,480 --> 00:19:44,280
in the upper atmosphere.

479
00:19:44,280 --> 00:19:45,620
<i>laughing</i>

480
00:19:45,620 --> 00:19:47,530
It's 19 km above ground

481
00:19:47,530 --> 00:19:49,990
and there is a sodium layer.

482
00:19:49,990 --> 00:19:52,070
And what you actually can do is

483
00:19:52,070 --> 00:19:54,870
you can take a laser on ground here,

484
00:19:54,870 --> 00:19:58,179
and then shot laser which corresponds

485
00:19:58,179 --> 00:20:02,630
to the energy transition of this sodium atoms

486
00:20:02,630 --> 00:20:07,610
which is 589.2 nm. It's orange.

487
00:20:07,610 --> 00:20:09,179
And excited those atoms up there

488
00:20:09,179 --> 00:20:09,960
in the atmosphere and they will

489
00:20:09,960 --> 00:20:10,620
start to glow.

490
00:20:10,620 --> 00:20:12,010
And if you have a focus,

491
00:20:12,010 --> 00:20:13,250
if you focus it in there,

492
00:20:13,250 --> 00:20:17,400
and than you have a blob of sodium atoms

493
00:20:17,400 --> 00:20:19,270
lighting up in the upper atmosphere,

494
00:20:19,270 --> 00:20:21,669
maybe... what ever some hundred meters long

495
00:20:21,669 --> 00:20:26,640
and some meters wide
as big as your focus is there.

496
00:20:26,640 --> 00:20:30,440
This can be done with a continuous laser.

497
00:20:30,440 --> 00:20:31,559
This has been done in the past.

498
00:20:31,559 --> 00:20:33,750
Yes, of course.

499
00:20:33,750 --> 00:20:37,100
And actually the first instruments

500
00:20:37,100 --> 00:20:39,360
were build like that.

501
00:20:39,360 --> 00:20:40,240
The thing is

502
00:20:40,240 --> 00:20:42,720
in those days they were very, very expensive.

503
00:20:42,720 --> 00:20:44,799
There is no sodium laser.

504
00:20:44,799 --> 00:20:50,260
There are only Di LASERs and they are messy

505
00:20:50,260 --> 00:20:52,030
and expensive.

506
00:20:52,030 --> 00:20:55,100
Nowadays we can build this as fibre laser

507
00:20:55,100 --> 00:20:57,730
but not ten 10 years ago or 15 years ago.

508
00:20:57,730 --> 00:21:00,070
An other solution is to actually

509
00:21:00,070 --> 00:21:03,470
use Rayleigh scattering in the atmosphere.

510
00:21:03,470 --> 00:21:06,220
You use a Nd-YAG LASER

511
00:21:06,220 --> 00:21:08,900
which is 532nm. It's green.

512
00:21:08,900 --> 00:21:10,650
It's easily available, it's cheap

513
00:21:10,650 --> 00:21:12,540
compared to the other one.

514
00:21:12,540 --> 00:21:15,860
And then you focus it in the atmosphere.

515
00:21:15,860 --> 00:21:17,820
The only thing is:

516
00:21:17,820 --> 00:21:19,770
You will do have backscatter of photons

517
00:21:19,770 --> 00:21:21,179
all along the way.

518
00:21:21,179 --> 00:21:22,410
So you have to think about

519
00:21:22,410 --> 00:21:24,620
how can I only record light from

520
00:21:24,620 --> 00:21:26,720
a certain height above ground?

521
00:21:26,720 --> 00:21:28,890
Because otherwise I don't have a spot,

522
00:21:28,890 --> 00:21:31,210
I have a ...ehhh... a laser beam column

523
00:21:31,210 --> 00:21:33,120
somewhere there.

524
00:21:33,120 --> 00:21:34,400
Okay!

525
00:21:34,400 --> 00:21:35,990
How do this things look like?

526
00:21:35,990 --> 00:21:37,960
Can we dim these lights actually a bit?

527
00:21:37,960 --> 00:21:40,000
Or is it only an off switch?

528
00:21:40,000 --> 00:21:45,169
Can you check on this? Let's check on there...

529
00:21:45,169 --> 00:21:49,040
Just push the button... come on...

530
00:21:49,040 --> 00:21:54,780
No? No. No!

531
00:21:54,780 --> 00:21:57,800
laughing

532
00:21:57,800 --> 00:22:06,380
Nooo!

533
00:22:06,380 --> 00:22:07,700
It's still on here...

534
00:22:07,700 --> 00:22:12,530
<i>gasp</i>

535
00:22:12,530 --> 00:22:16,540
All right, it's looking like this.

536
00:22:16,540 --> 00:22:19,380
Who has been at the camp?

537
00:22:19,380 --> 00:22:21,150
There was an astronomy talk at the camp

538
00:22:21,150 --> 00:22:24,910
from Liz.

539
00:22:24,910 --> 00:22:27,890
Actually if this talk had been tomorrow

540
00:22:27,890 --> 00:22:29,429
we would had have a live conference

541
00:22:29,429 --> 00:22:31,720
to that side because Liz is right now here

542
00:22:31,720 --> 00:22:35,050
and she send me that picture

543
00:22:35,050 --> 00:22:36,070
just some hours ago.

544
00:22:36,070 --> 00:22:38,520
That is how the just do things on

545
00:22:38,520 --> 00:22:41,059
Paranal in Chile.

546
00:22:41,059 --> 00:22:42,309
The thing I will talk about

547
00:22:42,309 --> 00:22:44,900
is the green one to the right.

548
00:22:44,900 --> 00:22:49,640
That's the thing I have been involved with.

549
00:22:49,640 --> 00:22:52,600
Yea, let's look into that.

550
00:22:52,600 --> 00:22:55,980
So if you shoot the laser into the atmosphere

551
00:22:55,980 --> 00:22:57,490
of course you do have problem.

552
00:22:57,490 --> 00:22:58,860
The star is very far away,

553
00:22:58,860 --> 00:23:00,790
it's infinitely far away.

554
00:23:00,790 --> 00:23:01,960
And the light that comes down

555
00:23:01,960 --> 00:23:05,100
is in a cylinder.

556
00:23:05,100 --> 00:23:08,660
And if you shoot a laser up, it's a cone.

557
00:23:08,660 --> 00:23:10,940
So you only probe the green region.

558
00:23:10,940 --> 00:23:15,580
The unsampled volume of turbulence
is to the side.

559
00:23:15,580 --> 00:23:18,650
That is a problem with our laser AO.

560
00:23:18,650 --> 00:23:26,200
An other problem we face is this one.

561
00:23:26,200 --> 00:23:30,140
When we take a star to measure the wave front

562
00:23:30,140 --> 00:23:33,380
then it passes only once through the atmosphere.

563
00:23:33,380 --> 00:23:35,530
The laser beam goes up and down.

564
00:23:35,530 --> 00:23:36,630
And so there is a component

565
00:23:36,630 --> 00:23:37,760
called tip tilt component

566
00:23:37,760 --> 00:23:40,870
which is actually just the thing moving around

567
00:23:40,870 --> 00:23:43,799
It's not just the phase

568
00:23:43,799 --> 00:23:45,929
that gets disturbance introduced

569
00:23:45,929 --> 00:23:48,600
in the wave front but this moving around.

570
00:23:48,600 --> 00:23:54,630
So not the bright and more
or less bright twinkling

571
00:23:54,630 --> 00:23:56,539
little star thingy,

572
00:23:56,539 --> 00:23:58,289
but the moving around.

573
00:23:58,289 --> 00:24:00,400
And that can not be sensed
with a laser guild star.

574
00:24:00,400 --> 00:24:02,549
So when ever we do laser AO

575
00:24:02,549 --> 00:24:04,570
We do need an other star

576
00:24:04,570 --> 00:24:05,600
to get this component.

577
00:24:05,600 --> 00:24:08,080
But this star can be a bit further away,

578
00:24:08,080 --> 00:24:11,669
like an arcminute or 2 arcminutes or so.

579
00:24:11,669 --> 00:24:17,150
So it's that... is wide. There are enough.

580
00:24:17,150 --> 00:24:18,490
And then we should think about

581
00:24:18,490 --> 00:24:20,220
actually what we have to correct and so

582
00:24:20,220 --> 00:24:23,789
we should make a profile of the turbulence

583
00:24:23,789 --> 00:24:25,100
above ground.

584
00:24:25,100 --> 00:24:27,059
And this is how it looks like.

585
00:24:27,059 --> 00:24:29,390
And for example for the side

586
00:24:29,390 --> 00:24:32,370
where we are there in Arizona

587
00:24:32,370 --> 00:24:34,450
we see that most of the turbulence

588
00:24:34,450 --> 00:24:37,400
is actually just above the ground.

589
00:24:37,400 --> 00:24:39,360
So we maybe should care mostly

590
00:24:39,360 --> 00:24:41,220
about the ground layer.

591
00:24:41,220 --> 00:24:44,559
It's not so much about the high altitude things.

592
00:24:44,559 --> 00:24:47,230
So and then what we do is:

593
00:24:47,230 --> 00:24:48,580
Well we want to sample

594
00:24:48,580 --> 00:24:50,660
the ground stuff nicely

595
00:24:50,660 --> 00:24:54,679
so we don't take one but 3 lasers.

596
00:24:54,679 --> 00:24:58,039
So to fill this area nicely.

597
00:24:58,039 --> 00:25:00,210
And yes, of course, we can also combine this

598
00:25:00,210 --> 00:25:03,410
and this looks like that.

599
00:25:03,410 --> 00:25:05,630
This combination we will not talk about today.

600
00:25:05,630 --> 00:25:09,809
We will only talk about that.

601
00:25:09,809 --> 00:25:11,080
This is how it looks like.

602
00:25:11,080 --> 00:25:13,110
So this is our telescope, the primary mirror

603
00:25:13,110 --> 00:25:16,590
which receives the light from outer space

604
00:25:16,590 --> 00:25:19,460
it then deflects on the secondary, tertiary

605
00:25:19,460 --> 00:25:20,600
and than somewhere here.

606
00:25:20,600 --> 00:25:22,610
But first we need to have to shoot the laser up.

607
00:25:22,610 --> 00:25:25,539
And it's launched from a laser box

608
00:25:25,539 --> 00:25:28,940
onto a mirror behind that secondary mirror

609
00:25:28,940 --> 00:25:30,530
over there into the atmosphere

610
00:25:30,530 --> 00:25:33,400
and after 40 microseconds it reaches

611
00:25:33,400 --> 00:25:36,200
an altitude of 12 km.

612
00:25:36,200 --> 00:25:37,620
And then of course it comes back.

613
00:25:37,620 --> 00:25:40,220
After 80 microseconds it's here

614
00:25:40,220 --> 00:25:41,419
in our detector again.

615
00:25:41,419 --> 00:25:43,730
So the star then lights up,

616
00:25:43,730 --> 00:25:46,050
has this cone, get's focused there, focus,

617
00:25:46,050 --> 00:25:48,460
reflected to here

618
00:25:48,460 --> 00:25:53,820
and we do have our signal
in our detector after 80 ms

619
00:25:53,820 --> 00:25:55,429
and as said, because of course

620
00:25:55,429 --> 00:25:59,070
the laser has scattering all along its path,

621
00:25:59,070 --> 00:26:03,350
you want to gate this information to 12 km

622
00:26:03,350 --> 00:26:05,539
and well then you just -just- look at

623
00:26:05,539 --> 00:26:06,880
when your laser pulse started

624
00:26:06,880 --> 00:26:09,419
wait. wait. wait. wait. wait.

625
00:26:09,419 --> 00:26:11,500
open the shutter for the detector

626
00:26:11,500 --> 00:26:14,980
for short time after 80ms,

627
00:26:14,980 --> 00:26:16,350
close it again and then analyse

628
00:26:16,350 --> 00:26:18,699
and read out what you just did.

629
00:26:18,699 --> 00:26:19,960
Easy, huh?

630
00:26:19,960 --> 00:26:21,520
So we are done.

631
00:26:21,520 --> 00:26:23,390
Thank you for coming to my talk

632
00:26:23,390 --> 00:26:26,400
and now go out and build your own lasers

633
00:26:26,400 --> 00:26:28,799
with... to...

634
00:26:28,799 --> 00:26:30,980
<i>laughing</i>

635
00:26:30,980 --> 00:26:34,309
Now we are going to look at this thing

636
00:26:34,309 --> 00:26:37,370
which is actually build and which works.

637
00:26:37,370 --> 00:26:39,650
So this is called ARGOS.

638
00:26:39,650 --> 00:26:41,250
It's a ground layer AO system.

639
00:26:41,250 --> 00:26:42,570
That's what we want to build.

640
00:26:42,570 --> 00:26:44,210
It has wide field corrections.

641
00:26:44,210 --> 00:26:46,110
That means you can not correct

642
00:26:46,110 --> 00:26:49,559
just a tiny patch on sky but for for astronomical use

643
00:26:49,559 --> 00:26:52,190
a huge area, meaning it's not just

644
00:26:52,190 --> 00:26:54,070
a circle of 10 arcseconds but

645
00:26:54,070 --> 00:26:56,850
this thing can correct 4 by 4 arcminutes

646
00:26:56,850 --> 00:26:58,230
which is huge,

647
00:26:58,230 --> 00:27:01,559
so all the objects that are in there.

648
00:27:01,559 --> 00:27:03,669
We have a multi-laser constellation.

649
00:27:03,669 --> 00:27:05,140
We have seen that why we need this,

650
00:27:05,140 --> 00:27:05,850
because we want to fill

651
00:27:05,850 --> 00:27:06,940
the complete ground layer.

652
00:27:06,940 --> 00:27:10,289
So we have 3 laser guild stars per eye.

653
00:27:10,289 --> 00:27:11,480
Why per eye?

654
00:27:11,480 --> 00:27:14,070
This will be clear in minute.

655
00:27:14,070 --> 00:27:17,419
And we use high power pulse green lasers.

656
00:27:17,419 --> 00:27:20,710
And this deformable mirror is actually

657
00:27:20,710 --> 00:27:22,970
build in the telescope system already.

658
00:27:22,970 --> 00:27:25,299
The secondary mirror is the deformable mirror

659
00:27:25,299 --> 00:27:26,960
which is very convenient,

660
00:27:26,960 --> 00:27:29,320
because then all the instruments,

661
00:27:29,320 --> 00:27:31,020
that sit on the telescope can benefit from

662
00:27:31,020 --> 00:27:33,980
this system.

663
00:27:33,980 --> 00:27:36,270
It's installed at this telescope.

664
00:27:36,270 --> 00:27:38,240
Look's pretty odd. Yes, I admit that.

665
00:27:38,240 --> 00:27:39,780
That's the Large Binocular Telescope.

666
00:27:39,780 --> 00:27:41,850
It's two telescopes on one mount.

667
00:27:41,850 --> 00:27:44,299
One primary, two primaries.

668
00:27:44,299 --> 00:27:47,570
It's roughly 23 by 25 by 12 meters.

669
00:27:47,570 --> 00:27:50,789
It sits on Mont Graham in Arizona.

670
00:27:50,789 --> 00:27:52,470
And it has an adaptive secondary mirror

671
00:27:52,470 --> 00:27:58,159
which is this violette coloured thingy

672
00:27:58,159 --> 00:28:00,630
up there in the middle on top.

673
00:28:00,630 --> 00:28:04,760
This is how it looks like.

674
00:28:04,760 --> 00:28:05,720
This is the control room

675
00:28:05,720 --> 00:28:06,800
where you sit.

676
00:28:06,800 --> 00:28:09,470
This stays fixed.

677
00:28:09,470 --> 00:28:11,890
All this shiny part rotates.

678
00:28:11,890 --> 00:28:12,860
That's the actual telescope,

679
00:28:12,860 --> 00:28:14,500
the red thing that moves up and down.

680
00:28:14,500 --> 00:28:17,169
So the whole building rotates and it moves

681
00:28:17,169 --> 00:28:19,210
up and down.

682
00:28:19,210 --> 00:28:27,419
It's from ceiling... the ceiling is at level
11.

683
00:28:27,419 --> 00:28:30,990
So when you actually sit there,

684
00:28:30,990 --> 00:28:34,779
you can watch around a bit

685
00:28:34,779 --> 00:28:39,960
... this is outside... it's winter... yuh!...
let's see...

686
00:28:39,960 --> 00:28:41,940
There is a ladder...

687
00:28:41,940 --> 00:28:46,070
Yes, this thing is huge...eh.. nice.. cool

688
00:28:46,070 --> 00:28:47,960
Okay, that's what it's looks like

689
00:28:47,960 --> 00:28:53,740
when you are actually there.

690
00:28:53,740 --> 00:28:56,870
Okay, our system layout is like this.

691
00:28:56,870 --> 00:28:59,789
We have this adaptive secondary mirror

692
00:28:59,789 --> 00:29:02,820
which is the deformable mirror.

693
00:29:02,820 --> 00:29:05,580
We have the primary, tertiary.

694
00:29:05,580 --> 00:29:06,900
That is clear already.

695
00:29:06,900 --> 00:29:11,520
So we have a laser box.

696
00:29:11,520 --> 00:29:15,240
The green things is the lasers themselfs.

697
00:29:15,240 --> 00:29:16,299
So that's how it looks like.

698
00:29:16,299 --> 00:29:18,179
We produce some laser beams.

699
00:29:18,179 --> 00:29:19,970
We have steering mirrors in there

700
00:29:19,970 --> 00:29:22,190
to get them into the right pattern on sky

701
00:29:22,190 --> 00:29:22,980
of course.

702
00:29:22,980 --> 00:29:24,330
We do have control cameras,

703
00:29:24,330 --> 00:29:25,870
if : Is the focus right?

704
00:29:25,870 --> 00:29:27,059
Is the position right?

705
00:29:27,059 --> 00:29:28,280
This is one control loop

706
00:29:28,280 --> 00:29:30,039
another control loop, another control loop

707
00:29:30,039 --> 00:29:31,590
an other control loop.

708
00:29:31,590 --> 00:29:33,140
The black thing is the shutter.

709
00:29:33,140 --> 00:29:35,030
Because we have to close this whole thing,

710
00:29:35,030 --> 00:29:36,870
when aircrafts are overhead,

711
00:29:36,870 --> 00:29:38,500
when satellites are overhead.

712
00:29:38,500 --> 00:29:40,120
So if you want to use this system,

713
00:29:40,120 --> 00:29:43,100
you have to, 6 weeks in advance, you have to

714
00:29:43,100 --> 00:29:45,809
put out your list of observable targets

715
00:29:45,809 --> 00:29:47,230
to some military agency.

716
00:29:47,230 --> 00:29:49,309
And they will tell you: Okay! Not Okay!

717
00:29:49,309 --> 00:29:51,840
Okay! Not Okay! Not Okay! Not Okay! Okay!

718
00:29:51,840 --> 00:29:54,600
Not Okay, meaning something is passing overhead.

719
00:29:54,600 --> 00:29:56,710
Hmm... what could this be?

720
00:29:56,710 --> 00:30:03,460
<i>laughing</i>

721
00:30:03,460 --> 00:30:04,950
Of course, at some point the lasers

722
00:30:04,950 --> 00:30:07,360
come down again in this cone shape.

723
00:30:07,360 --> 00:30:11,039
They will reach the primary mirror

724
00:30:11,039 --> 00:30:14,110
and ultimately it will end up

725
00:30:14,110 --> 00:30:15,210
in the wave front sensor

726
00:30:15,210 --> 00:30:18,270
which is much more complex than just this box.

727
00:30:18,270 --> 00:30:21,929
I showed you before.

728
00:30:21,929 --> 00:30:23,220
So there are aquisition cameras

729
00:30:23,220 --> 00:30:25,409
which detect are we at the right spot.

730
00:30:25,409 --> 00:30:27,990
Do the spots get onto the detector

731
00:30:27,990 --> 00:30:29,789
in a nice fashion.

732
00:30:29,789 --> 00:30:31,659
We do have to do this gating, remember?

733
00:30:31,659 --> 00:30:33,020
We have to open this shutter

734
00:30:33,020 --> 00:30:36,570
for the CCD when we want to record the light.

735
00:30:36,570 --> 00:30:39,659
This tiny fraction after 80ms.

736
00:30:39,659 --> 00:30:43,510
After the laser pulse has been launched.

737
00:30:43,510 --> 00:30:44,250
It's done in here.

738
00:30:44,250 --> 00:30:45,179
These are Pockel Cells.

739
00:30:45,179 --> 00:30:49,320
So its an electro optical effect.

740
00:30:49,320 --> 00:30:53,980
And then there is also something

741
00:30:53,980 --> 00:30:55,940
in addition because I said

742
00:30:55,940 --> 00:30:58,549
we can't do without the tip tilt

743
00:30:58,549 --> 00:31:00,049
and there is another unit in here

744
00:31:00,049 --> 00:31:03,059
that sits right in front of the science instrument

745
00:31:03,059 --> 00:31:04,799
that detects this tip tilt star,

746
00:31:04,799 --> 00:31:08,140
this additional star.

747
00:31:08,140 --> 00:31:11,020
So you have the laser wave front light,

748
00:31:11,020 --> 00:31:13,970
the green one, you do have this tip tilt light,

749
00:31:13,970 --> 00:31:15,049
the blue one,

750
00:31:15,049 --> 00:31:17,080
and you do have the actual science light

751
00:31:17,080 --> 00:31:20,250
from the object you want to observe on sky.

752
00:31:20,250 --> 00:31:22,799
That goes directly into this scientific instrument

753
00:31:22,799 --> 00:31:25,250
in the end.

754
00:31:25,250 --> 00:31:28,020
And then you have a lot of control things.

755
00:31:28,020 --> 00:31:29,929
Of course, you do need a common clock

756
00:31:29,929 --> 00:31:33,470
for this synchronization of all this pulses

757
00:31:33,470 --> 00:31:35,760
and the gating and what not.

758
00:31:35,760 --> 00:31:37,260
And of course you need the information

759
00:31:37,260 --> 00:31:40,260
for the tip tilt component and for the wave
front

760
00:31:40,260 --> 00:31:41,440
into this computer

761
00:31:41,440 --> 00:31:44,110
which sends then all the slops

762
00:31:44,110 --> 00:31:45,760
- you remember we have to do this

763
00:31:45,760 --> 00:31:48,760
linear approximation pieces wise, yes -

764
00:31:48,760 --> 00:31:49,929
into the secondary mirror

765
00:31:49,929 --> 00:31:52,880
which than deforms in real time.

766
00:31:52,880 --> 00:31:57,120
And does this a thousand times a second.

767
00:31:57,120 --> 00:31:59,470
This is how it looks like.

768
00:31:59,470 --> 00:32:05,210
So when I am there I am roughly that tall.

769
00:32:05,210 --> 00:32:08,000
The two black tubes right in the middle,

770
00:32:08,000 --> 00:32:11,960
those are the two tubes which go up.

771
00:32:11,960 --> 00:32:14,710
Looks like this.

772
00:32:14,710 --> 00:32:17,529
So, this is how the components are distributed

773
00:32:17,529 --> 00:32:21,460
over the telescope... once back.. okay

774
00:32:21,460 --> 00:32:24,220
primary mirror, primary mirror,

775
00:32:24,220 --> 00:32:26,390
some instruments in the middle,

776
00:32:26,390 --> 00:32:28,409
some tertiary mirror,

777
00:32:28,409 --> 00:32:31,839
the secondaries, the adaptive ones up there.

778
00:32:31,839 --> 00:32:37,900
Yes, I hate to use this laser pointers.

779
00:32:37,900 --> 00:32:39,440
<i>laughing</i>

780
00:32:39,440 --> 00:32:40,690
Because I am always going like this... eee

781
00:32:40,690 --> 00:32:44,520
(green laser pointer on the slides)

782
00:32:44,520 --> 00:32:48,610
<i>laughing</i>

783
00:32:48,610 --> 00:32:52,939
That's my man! <i>laughing</i>

784
00:32:52,939 --> 00:32:54,650
So okay!

785
00:32:54,650 --> 00:32:58,440
So we do have the adaptive secondary

786
00:32:58,440 --> 00:33:00,940
up there and then it goes back on the

787
00:33:00,940 --> 00:33:02,860
tertiary down there and then it goes over

788
00:33:02,860 --> 00:33:04,580
into the science instrument,

789
00:33:04,580 --> 00:33:11,999
all the wave front sensors and what not.

790
00:33:11,999 --> 00:33:14,879
Again, we do have a laser system.

791
00:33:14,879 --> 00:33:16,760
We have to place somewhere a launch system

792
00:33:16,760 --> 00:33:19,700
for the laser, a dichroic to separate

793
00:33:19,700 --> 00:33:23,480
between the laser light, the tip tilt light
and the science light.

794
00:33:23,480 --> 00:33:25,460
We do have to have a wave front sensor

795
00:33:25,460 --> 00:33:27,529
to check how the wave front looks like.

796
00:33:27,529 --> 00:33:29,039
We do have to have this tip tilt control.

797
00:33:29,039 --> 00:33:29,890
We have calibration source.

798
00:33:29,890 --> 00:33:31,240
A calibration source would be nice

799
00:33:31,240 --> 00:33:33,510
to calibrate the system during daytime,

800
00:33:33,510 --> 00:33:38,260
aircraft detection, yes, satellite avoidance,

801
00:33:38,260 --> 00:33:41,279
-also an issue here- and a control software.

802
00:33:41,279 --> 00:33:43,840
There are many people just writing...

803
00:33:43,840 --> 00:33:45,830
...just haha... writing software for this.

804
00:33:45,830 --> 00:33:51,350
And this is really hard.

805
00:33:51,350 --> 00:33:53,179
Some are also on the conference.

806
00:33:53,179 --> 00:33:54,370
They don't want to be pointed out

807
00:33:54,370 --> 00:33:56,200
as I learned, but you will find them

808
00:33:56,200 --> 00:34:01,059
at the conference, if you look at the right places.

809
00:34:01,059 --> 00:34:05,700
That's where the laser box is located.

810
00:34:05,700 --> 00:34:09,449
Just next to it is the electronics rack.

811
00:34:09,449 --> 00:34:10,839
How does this thing look like?

812
00:34:10,839 --> 00:34:12,730
So that is one of our lasers.

813
00:34:12,730 --> 00:34:17,839
It's about 20 W. Don't get your finger in there.

814
00:34:17,839 --> 00:34:19,099
<i>laughing</i>

815
00:34:19,099 --> 00:34:20,940
It really hurts.

816
00:34:20,940 --> 00:34:25,329
(Did you try?) No!

817
00:34:25,329 --> 00:34:30,260
There is a mandatory annual laser training of course.

818
00:34:30,260 --> 00:34:34,679
Yes, if you want to have something
like this at home,

819
00:34:34,679 --> 00:34:37,280
you do need a huge refrigerator next to it

820
00:34:37,280 --> 00:34:38,940
just for the cooling of that thing.

821
00:34:38,940 --> 00:34:41,580
This is nothing you want to have at home.

822
00:34:41,580 --> 00:34:46,418
Just because it's... that bulky... no..it's
not..

823
00:34:46,418 --> 00:34:47,818
but actually when you do

824
00:34:47,818 --> 00:34:49,379
this green laser pointer thingy

825
00:34:49,379 --> 00:34:50,790
then there is always this always this:

826
00:34:50,790 --> 00:34:52,770
"Don't use this for more than 10 seconds."

827
00:34:52,770 --> 00:34:54,429
Because why? Because the crystal inside

828
00:34:54,429 --> 00:34:55,429
heats up.

829
00:34:55,429 --> 00:34:56,980
And if you can't dissipate that heat

830
00:34:56,980 --> 00:34:58,770
the crystal at some point breaks

831
00:34:58,770 --> 00:35:00,710
and then your laser pointer is broken.

832
00:35:00,710 --> 00:35:02,990
This thing gets continuously cooled.

833
00:35:02,990 --> 00:35:06,510
So, therefore it's a bit more expensive.

834
00:35:06,510 --> 00:35:08,960
<i>laughing</i>

835
00:35:08,960 --> 00:35:10,250
If you than put it up,

836
00:35:10,250 --> 00:35:12,190
so this is still on the lab table

837
00:35:12,190 --> 00:35:13,589
when it was integrated and tested

838
00:35:13,589 --> 00:35:15,530
and than at some point it gets put all

839
00:35:15,530 --> 00:35:17,820
in a box with all this control mirrors

840
00:35:17,820 --> 00:35:20,020
and cameras and what not.

841
00:35:20,020 --> 00:35:22,030
But finally you see in the middle

842
00:35:22,030 --> 00:35:23,520
on this picture there is

843
00:35:23,520 --> 00:35:26,010
a focusing lens and then you see

844
00:35:26,010 --> 00:35:29,300
these 3 tiny little beam coming out of there

845
00:35:29,300 --> 00:35:32,359
which than expand on sky in size

846
00:35:32,359 --> 00:35:36,089
of course when they are in 12 km height

847
00:35:36,089 --> 00:35:38,730
but that's how they come out of it.

848
00:35:38,730 --> 00:35:41,339
And if you install this in the telescope,

849
00:35:41,339 --> 00:35:42,869
you actually have to tilt the telescope,

850
00:35:42,869 --> 00:35:44,280
because otherwise you can't reach it.

851
00:35:44,280 --> 00:35:48,880
And then you need your climbing gear.

852
00:35:48,880 --> 00:35:50,520
So once you have produced the lasers,

853
00:35:50,520 --> 00:35:52,310
you need to propagate them to a through

854
00:35:52,310 --> 00:35:57,849
a dust tube onto a launch mirror,

855
00:35:57,849 --> 00:36:00,369
a folding mirror and from there to

856
00:36:00,369 --> 00:36:02,960
a launch mirror.

857
00:36:02,960 --> 00:36:06,460
Yes and then it looks like this!

858
00:36:06,460 --> 00:36:09,730
Okay, so the lasers come from here into that

859
00:36:09,730 --> 00:36:11,690
and then over to the other side

860
00:36:11,690 --> 00:36:14,859
over the secondary mirror and then

861
00:36:14,859 --> 00:36:17,920
being shot right up into space

862
00:36:17,920 --> 00:36:20,450
like this.

863
00:36:20,450 --> 00:36:23,950
Okay, so if you want to have that at home,

864
00:36:23,950 --> 00:36:27,020
.... eh... but I can tell you the whole facility

865
00:36:27,020 --> 00:36:31,980
does cost less than one fully equipped Eurofighter

866
00:36:31,980 --> 00:36:44,750
<i>laughing</i>
<i>applause</i>

867
00:36:44,750 --> 00:36:48,470
Thank you for taking the hint.

868
00:36:48,470 --> 00:36:50,339
Yeah, that's how it looks like.

869
00:36:50,339 --> 00:36:53,260
It's.... yes it's... <i>laughing</i> ... yeah...

870
00:36:53,260 --> 00:36:56,620
<i>laughing</i><i>applause</i> Okay?

871
00:36:56,620 --> 00:36:59,960
okay... I have to admit this are a bit longer exposers.

872
00:36:59,960 --> 00:37:01,420
It's not that bright and green

873
00:37:01,420 --> 00:37:04,450
when you are actually at the telescope up
there.

874
00:37:04,450 --> 00:37:07,510
But if you have been in the dark long enough

875
00:37:07,510 --> 00:37:11,460
around ten minutes, then I really becomes bright.

876
00:37:11,460 --> 00:37:13,640
There is a little telescope that observes,

877
00:37:13,640 --> 00:37:15,859
where actually the spots are on sky.

878
00:37:15,859 --> 00:37:17,089
And if we have clear sky,

879
00:37:17,089 --> 00:37:19,260
then we have this constellation on the right.

880
00:37:19,260 --> 00:37:21,830
So that is how the lasers come up.

881
00:37:21,830 --> 00:37:25,330
As I said you do see them all the way up,

882
00:37:25,330 --> 00:37:26,990
but we are interested in the little dots

883
00:37:26,990 --> 00:37:27,490
at the end.

884
00:37:27,490 --> 00:37:28,910
You can barely see them.

885
00:37:28,910 --> 00:37:30,190
If there are high clouds,

886
00:37:30,190 --> 00:37:36,080
well than we produce something like this.

887
00:37:36,080 --> 00:37:39,000
We have the dichroic when the light comes
back down

888
00:37:39,000 --> 00:37:39,930
as said.

889
00:37:39,930 --> 00:37:42,349
Which separates the science light in red

890
00:37:42,349 --> 00:37:44,320
and the laser light in green.

891
00:37:44,320 --> 00:37:46,030
This is how it looks like.

892
00:37:46,030 --> 00:37:49,890
Actually the dichroic is right in front of
Sebatian there

893
00:37:49,890 --> 00:37:51,930
and from there it gets then reflected

894
00:37:51,930 --> 00:37:55,220
on a reflector and then up into the

895
00:37:55,220 --> 00:37:59,310
wave front sensing unit.

896
00:37:59,310 --> 00:38:03,990
So there is the dichroic, there is the reflector,

897
00:38:03,990 --> 00:38:06,420
and it goes over in this unit

898
00:38:06,420 --> 00:38:11,300
which is the wave front sensing unit

899
00:38:11,300 --> 00:38:13,349
which sits there, at the side.

900
00:38:13,349 --> 00:38:20,150
That's how it looks, when it gets installed.

901
00:38:20,150 --> 00:38:22,359
And that is how it looks inside.

902
00:38:22,359 --> 00:38:24,160
So you have the 3 laser beams coming

903
00:38:24,160 --> 00:38:26,619
from the side, from the sky, of course.

904
00:38:26,619 --> 00:38:27,720
You have patrol cameras

905
00:38:27,720 --> 00:38:30,030
which monitor where are these?

906
00:38:30,030 --> 00:38:32,570
Are they at the right spot?

907
00:38:32,570 --> 00:38:36,330
Do we have to steer the lasers a bit?

908
00:38:36,330 --> 00:38:42,160
Than we have some control for the position

909
00:38:42,160 --> 00:38:45,760
of the laser spots and the field.

910
00:38:45,760 --> 00:38:47,310
The Pockel cells are the ones

911
00:38:47,310 --> 00:38:49,520
that do this opening and closing in front

912
00:38:49,520 --> 00:38:50,230
of the shutter.

913
00:38:50,230 --> 00:38:52,089
You can't use a mechanic shutter in front

914
00:38:52,089 --> 00:38:52,890
of the CCD.

915
00:38:52,890 --> 00:38:55,280
We have to do this electro optically

916
00:38:55,280 --> 00:38:59,970
So you have a polarization of the laserbeams.

917
00:38:59,970 --> 00:39:03,440
And you have a polarizer... a cross polarizer

918
00:39:03,440 --> 00:39:05,420
and then you just turn the polarisation

919
00:39:05,420 --> 00:39:06,740
of the crystals.

920
00:39:06,740 --> 00:39:08,410
It's an electro optical effect

921
00:39:08,410 --> 00:39:10,700
and then it gets passed through

922
00:39:10,700 --> 00:39:12,700
or it gets blocked.

923
00:39:12,700 --> 00:39:15,540
Then you also of course have this lens slit arrays

924
00:39:15,540 --> 00:39:19,080
in there and then the CCD

925
00:39:19,080 --> 00:39:21,599
which actually records this dot pattern.

926
00:39:21,599 --> 00:39:23,470
You remember, this 4 by 4...

927
00:39:23,470 --> 00:39:25,540
well it's not 4 by 4 in our case we do

928
00:39:25,540 --> 00:39:28,660
have a bit more resolution.

929
00:39:28,660 --> 00:39:32,339
The sensory looks like this.

930
00:39:32,339 --> 00:39:35,589
This is actually a custom build CCD.

931
00:39:35,589 --> 00:39:37,170
Very special.

932
00:39:37,170 --> 00:39:38,599
The imaging area is in the middle

933
00:39:38,599 --> 00:39:40,990
and when you read out the thing,

934
00:39:40,990 --> 00:39:43,250
you split the image in half,

935
00:39:43,250 --> 00:39:44,720
you transfer it to the sides

936
00:39:44,720 --> 00:39:46,960
to the frame store area and than read it out.

937
00:39:46,960 --> 00:39:49,210
'Cause read out is slow, transfer is fast.

938
00:39:49,210 --> 00:39:51,380
And you have to do this a thousand times

939
00:39:51,380 --> 00:39:54,190
a second at very low read out noise,

940
00:39:54,190 --> 00:39:58,560
which is only 4 electron read out noise.

941
00:39:58,560 --> 00:40:01,109
For the experts here in the audience,

942
00:40:01,109 --> 00:40:05,030
this is very good.

943
00:40:05,030 --> 00:40:08,280
It's not many pixels but it's more than enough for us.

944
00:40:08,280 --> 00:40:09,730
So how does this look like?

945
00:40:09,730 --> 00:40:11,030
It looks like that!

946
00:40:11,030 --> 00:40:13,380
So there you have your pattern again,

947
00:40:13,380 --> 00:40:15,130
regularly spaces pattern of course

948
00:40:15,130 --> 00:40:19,310
from 3 laser guild stars you get 3 patterns

949
00:40:19,310 --> 00:40:21,900
and then you analyse, well, the position,

950
00:40:21,900 --> 00:40:24,230
the relative position, the absolute position

951
00:40:24,230 --> 00:40:26,490
of those stars on their grid,

952
00:40:26,490 --> 00:40:29,530
and somehow compute this slopes

953
00:40:29,530 --> 00:40:33,070
from there feed them back, compute then

954
00:40:33,070 --> 00:40:35,530
actually electrical information from them

955
00:40:35,530 --> 00:40:37,450
which you can than feed into your

956
00:40:37,450 --> 00:40:39,240
deformable mirror again

957
00:40:39,240 --> 00:40:42,950
which sits on top of the telescope

958
00:40:42,950 --> 00:40:47,180
and then hopefully everything works.

959
00:40:47,180 --> 00:40:49,780
This you can digest at home.
<i>laughing</i>

960
00:40:49,780 --> 00:40:52,220
It's in the stream now so it will be

961
00:40:52,220 --> 00:40:54,329
saved for all eternity

962
00:40:54,329 --> 00:40:55,240
and all the aliens

963
00:40:55,240 --> 00:40:57,940
which record all the electromagnetic field

964
00:40:57,940 --> 00:41:00,790
from Bielefeld... (mumbling)

965
00:41:00,790 --> 00:41:02,050
<i>laughing</i>

966
00:41:02,050 --> 00:41:05,579
Anyway, so, just in short.

967
00:41:05,579 --> 00:41:08,550
There is down in green there is this thing

968
00:41:08,550 --> 00:41:12,140
that goes up from the lasers through

969
00:41:12,140 --> 00:41:14,660
some steering mirrors.

970
00:41:14,660 --> 00:41:19,710
We have diagnostics, then we got to focus

971
00:41:19,710 --> 00:41:21,530
check launch mirror one and launch mirror two

972
00:41:21,530 --> 00:41:24,579
onto sky and then we go back

973
00:41:24,579 --> 00:41:27,000
up there N1 is the primary mirror.

974
00:41:27,000 --> 00:41:29,099
And then we go through this whole chain

975
00:41:29,099 --> 00:41:31,740
and there are various control loops

976
00:41:31,740 --> 00:41:35,109
sitting in there.

977
00:41:35,109 --> 00:41:37,070
And all this things have to talk together

978
00:41:37,070 --> 00:41:40,720
on very high rates.

979
00:41:40,720 --> 00:41:44,579
Sometimes you see 1 kHz other things are a bit slower.

980
00:41:44,579 --> 00:41:50,030
This all needs highly sophisticated control software.

981
00:41:50,030 --> 00:41:51,950
And the programmers can be real proud

982
00:41:51,950 --> 00:41:54,050
of what they did in the past

983
00:41:54,050 --> 00:41:56,990
with all this control loops.

984
00:41:56,990 --> 00:42:00,200
The tip tilt is very... much much much easier,

985
00:42:00,200 --> 00:42:00,829
because all the...

986
00:42:00,829 --> 00:42:01,960
you remember this tip tilt

987
00:42:01,960 --> 00:42:03,400
so this all is moving around.

988
00:42:03,400 --> 00:42:06,030
So you have 4 quadrants at a little cell

989
00:42:06,030 --> 00:42:08,390
and it moves to somewhere up, down,

990
00:42:08,390 --> 00:42:09,060
left, right.

991
00:42:09,060 --> 00:42:10,760
You can easily detect that.

992
00:42:10,760 --> 00:42:14,280
That is feed into an array

993
00:42:14,280 --> 00:42:17,470
of 4 Avalanche Photon Diodes

994
00:42:17,470 --> 00:42:20,020
to actually record this and for that

995
00:42:20,020 --> 00:42:22,119
we don't need many photons.

996
00:42:22,119 --> 00:42:24,180
So this tip tilt star can comparably...

997
00:42:24,180 --> 00:42:28,130
be comparably dim.

998
00:42:28,130 --> 00:42:30,680
The calibration unit for the daytime calibration

999
00:42:30,680 --> 00:42:32,130
can be put into the beam,

1000
00:42:32,130 --> 00:42:34,150
so this arms can swing over,

1001
00:42:34,150 --> 00:42:35,750
over the primary mirror and then we can

1002
00:42:35,750 --> 00:42:40,910
inject artificial stars via a hologram

1003
00:42:40,910 --> 00:42:42,890
into the whole unit during daytime

1004
00:42:42,890 --> 00:42:44,510
and calibrate this whole thing.

1005
00:42:44,510 --> 00:42:48,560
And than yes, we are back here.

1006
00:42:48,560 --> 00:42:52,210
This is how we look like.

1007
00:42:52,210 --> 00:42:57,460
Maybe concentrate on this two areas first.

1008
00:42:57,460 --> 00:43:00,750
I will flip back an forth many times.

1009
00:43:00,750 --> 00:43:02,260
But, yeah, what is this?

1010
00:43:02,260 --> 00:43:04,400
Are this two stars which are just fuzzy

1011
00:43:04,400 --> 00:43:05,700
and dim?

1012
00:43:05,700 --> 00:43:07,510
Or is this an extended object?

1013
00:43:07,510 --> 00:43:09,480
The upper one may be a galaxy because it's

1014
00:43:09,480 --> 00:43:11,030
elongated.

1015
00:43:11,030 --> 00:43:13,970
Okay, concentrate on that.

1016
00:43:13,970 --> 00:43:24,450
Well, it actually just a bunch of stars.

1017
00:43:24,450 --> 00:43:26,099
And this is over a huge field.

1018
00:43:26,099 --> 00:43:28,170
So the correction is not just in the middle

1019
00:43:28,170 --> 00:43:30,570
but you can see also at the very edges

1020
00:43:30,570 --> 00:43:33,040
of this image, we do see this improvement

1021
00:43:33,040 --> 00:43:34,540
in image quality.

1022
00:43:34,540 --> 00:43:39,480
Of course you can have the diagram, if you want.

1023
00:43:39,480 --> 00:43:43,190
So the blue line is without the thing beam activated,

1024
00:43:43,190 --> 00:43:44,300
open loop,

1025
00:43:44,300 --> 00:43:46,349
and if we close the control loop, to do

1026
00:43:46,349 --> 00:43:49,040
this measurement and correction in real time

1027
00:43:49,040 --> 00:43:53,589
we do squeeze all the energy into a few pixels

1028
00:43:53,589 --> 00:43:54,800
which of course also means

1029
00:43:54,800 --> 00:43:57,730
our signal to noise level in a single pixel

1030
00:43:57,730 --> 00:43:59,140
goes up tremendously.

1031
00:43:59,140 --> 00:44:00,460
Meaning you can decrease

1032
00:44:00,460 --> 00:44:03,320
your exposer time.

1033
00:44:03,320 --> 00:44:06,200
Which is important if you want to observe
galaxies

1034
00:44:06,200 --> 00:44:09,349
at this telescopes

1035
00:44:09,349 --> 00:44:12,480
it's 200 Dollars a minute.

1036
00:44:12,480 --> 00:44:16,460
<i>laughing</i>

1037
00:44:16,460 --> 00:44:18,370
It's not cheap.

1038
00:44:18,370 --> 00:44:23,920
Okay, good so... the thing...

1039
00:44:23,920 --> 00:44:27,520
just last week there was
another commissioning run

1040
00:44:27,520 --> 00:44:30,339
testing commissioning run for this system.

1041
00:44:30,339 --> 00:44:34,420
And my colleges José Borelli and Lorenzo Busoni

1042
00:44:34,420 --> 00:44:36,450
have done a nice video.

1043
00:44:36,450 --> 00:44:38,810
The music btw. "hallo gamer"

1044
00:44:38,810 --> 00:44:42,599
it's royalty for ears...

1045
00:44:42,599 --> 00:44:46,040
If it was now darker therefore I asked,

1046
00:44:46,040 --> 00:44:47,880
this would come up nicer,

1047
00:44:47,880 --> 00:44:49,060
but let's see!

1048
00:44:49,060 --> 00:44:50,880
There is sound hopefully,

1049
00:44:50,880 --> 00:44:53,260
so the sound guys, let's see!

1050
00:46:40,720 --> 00:47:00,020
<i>applause</i>

1051
00:47:00,020 --> 00:47:02,540
Of course this a longer exposure.

1052
00:47:02,540 --> 00:47:07,089
It's not that starwars like

1053
00:47:07,089 --> 00:47:09,810
I would have loved to use some starwars

1054
00:47:09,810 --> 00:47:13,349
tones along those. But you know, all those rights

1055
00:47:13,349 --> 00:47:16,640
and... what not... yes... anyway!

1056
00:47:16,640 --> 00:47:17,770
That's how it looks like.

1057
00:47:17,770 --> 00:47:22,559
So you have 3 laser beams per eye.

1058
00:47:22,559 --> 00:47:24,910
Remember, we have 2 telescopes on one mount.

1059
00:47:24,910 --> 00:47:26,490
They look roughly in the same direction

1060
00:47:26,490 --> 00:47:28,630
but still...

1061
00:47:28,630 --> 00:47:31,460
So if you observe two telescopes

1062
00:47:31,460 --> 00:47:39,640
at the same time it's only 100 dollars a minute.

1063
00:47:39,640 --> 00:47:44,270
Yea, This is not so much the shiny part

1064
00:47:44,270 --> 00:47:47,130
on the dome itself, but if you actually

1065
00:47:47,130 --> 00:47:49,240
do stand on the mountain during night

1066
00:47:49,240 --> 00:47:50,859
and are a bit dark adapted,

1067
00:47:50,859 --> 00:47:54,800
you see the laser beams like that.

1068
00:47:54,800 --> 00:47:57,230
And don't be fooled!

1069
00:47:57,230 --> 00:47:59,770
If you are at the valley,

1070
00:47:59,770 --> 00:48:02,560
or very far away you hardly see them.

1071
00:48:02,560 --> 00:48:03,829
You don't see them at all.

1072
00:48:03,829 --> 00:48:04,990
You see them there.

1073
00:48:04,990 --> 00:48:08,079
If you are two kilometers off side already,

1074
00:48:08,079 --> 00:48:10,650
it's merely a dim greenish something.

1075
00:48:10,650 --> 00:48:13,390
If you are down in the valley 10 km off,

1076
00:48:13,390 --> 00:48:14,640
you don't see them any more.

1077
00:48:14,640 --> 00:48:17,460
If you take a camera, 5 minutes exposer, yes!

1078
00:48:17,460 --> 00:48:18,919
But otherwise, No!

1079
00:48:18,919 --> 00:48:20,180
There is no such thing as

1080
00:48:20,180 --> 00:48:22,690
"The people in the valley down can see like

1081
00:48:22,690 --> 00:48:29,350
these lasers pew pew every night.".. and no.

1082
00:48:29,350 --> 00:48:37,330
Ok, which gets me to the last part.

1083
00:48:37,330 --> 00:48:40,089
How, do you become

1084
00:48:40,089 --> 00:48:45,949
and how do you work as a laser rocket scientist?

1085
00:48:45,949 --> 00:48:48,099
Yes, I put this in the talk directly,

1086
00:48:48,099 --> 00:48:50,660
because I do get this question in the Q&A, normally,

1087
00:48:50,660 --> 00:48:52,690
when I talk about these things,

1088
00:48:52,690 --> 00:48:53,670
and it's always like:

1089
00:48:53,670 --> 00:48:58,659
"What do I need to do if I want to do this?"

1090
00:48:58,659 --> 00:49:01,520
Maybe you have already an idea about this

1091
00:49:01,520 --> 00:49:05,119
because you have seen
how complex this thing is.

1092
00:49:05,119 --> 00:49:12,859
And, there are so many things to do in these
kind of projects

1093
00:49:12,859 --> 00:49:16,150
and on various levels, also in the administration,

1094
00:49:16,150 --> 00:49:22,450
also for senior people, new people, maybe
master thesis works on that

1095
00:49:22,450 --> 00:49:28,819
or bachelor, or PHD or then as a post-doc.

1096
00:49:28,819 --> 00:49:30,160
It's very complex.

1097
00:49:30,160 --> 00:49:34,150
Yes, and it's not only about just shooting
lasers in the end.

1098
00:49:34,150 --> 00:49:39,250
Sometimes it's just about checking the cables

1099
00:49:39,250 --> 00:49:41,020
It needs to be done.

1100
00:49:41,020 --> 00:49:45,690
There is a tremendous amount of electronics
and electrics involved.

1101
00:49:45,690 --> 00:49:52,240
There are all the mechanical components in
such a system are custom built.

1102
00:49:52,240 --> 00:49:55,579
Either the institutes built it themselves

1103
00:49:55,579 --> 00:49:59,210
or they give it out of house.

1104
00:49:59,210 --> 00:50:01,319
There are these real time computers, for example.

1105
00:50:01,319 --> 00:50:02,829
this is by the way our real time computer

1106
00:50:02,829 --> 00:50:05,880
from micrograde, if you want to look that up.

1107
00:50:05,880 --> 00:50:08,460
it's company. It builds these things.

1108
00:50:08,460 --> 00:50:10,650
They need to be programmed.

1109
00:50:10,650 --> 00:50:13,579
Oh, if actually somebody is here in the audience

1110
00:50:13,579 --> 00:50:15,599
with real hard core experience on

1111
00:50:15,599 --> 00:50:18,750
real time computing, coding and such things,

1112
00:50:18,750 --> 00:50:20,590
do talk to me!

1113
00:50:20,590 --> 00:50:23,540
<i>laughing</i>

1114
00:50:23,540 --> 00:50:26,540
Yeah, this is how our software system looks like.

1115
00:50:26,540 --> 00:50:31,839
A very small part of the GUIs. It's a lot of code

1116
00:50:31,839 --> 00:50:35,010
and a lot of work and a lot of sleepless nights

1117
00:50:35,010 --> 00:50:38,760
in front of these computers
and just testing it and testing it

1118
00:50:38,760 --> 00:50:41,829
and then testing some more,
and testing even more.

1119
00:50:41,829 --> 00:50:44,859
And, to be involved in these kind of projects,

1120
00:50:44,859 --> 00:50:48,560
you don't need to be a laser physicist,

1121
00:50:48,560 --> 00:50:51,479
because there is no one thing.

1122
00:50:51,479 --> 00:50:54,890
If you want to take 3 messages
out of this, it's:

1123
00:50:54,890 --> 00:50:57,060
it's a team effort, there are many tasks,

1124
00:50:57,060 --> 00:51:01,499
and there are many jobs,
and you have to pick one.

1125
00:51:01,499 --> 00:51:04,170
Because in this one job you do in these projects

1126
00:51:04,170 --> 00:51:06,500
you have to be very, very, very good.

1127
00:51:06,500 --> 00:51:09,750
Because there are other people that are very,
very, very good.

1128
00:51:09,750 --> 00:51:13,650
If you work in these kind of projects, if
you meet a new person for the first time

1129
00:51:13,650 --> 00:51:17,359
just assume that he or she knows
everything about this

1130
00:51:17,359 --> 00:51:18,940
and you know nothing.

1131
00:51:18,940 --> 00:51:24,130
You will quickly realize if that is true.

1132
00:51:24,130 --> 00:51:26,319
But otherwise, if you assume it
the other way round,

1133
00:51:26,319 --> 00:51:28,730
you just make a fool of yourself, okay?

1134
00:51:28,730 --> 00:51:29,849
Don't do that.

1135
00:51:29,849 --> 00:51:34,170
People in science, second most important thing
if you really want go into this,

1136
00:51:34,170 --> 00:51:38,740
people in science are just like
people outside science

1137
00:51:38,740 --> 00:51:42,429
meaning you will meet nice people
and you will meet.....

1138
00:51:42,429 --> 00:51:44,800
<i>laughing</i>

1139
00:51:44,800 --> 00:51:47,480
just like in life.

1140
00:51:47,480 --> 00:51:52,470
It's not that these things are spheres
where people are, you know

1141
00:51:52,470 --> 00:51:57,180
floating above the lab surface and nice coloured.

1142
00:51:57,180 --> 00:52:00,819
No, it's hard work.

1143
00:52:00,819 --> 00:52:04,829
And if you actually go into this
like study physics

1144
00:52:04,829 --> 00:52:08,640
or maybe if you want to construct this,

1145
00:52:08,640 --> 00:52:10,480
of course all the drawings are done by

1146
00:52:10,480 --> 00:52:13,339
people how have learned this in there studies,

1147
00:52:13,339 --> 00:52:16,810
so "Maschinenbau" what ever...

1148
00:52:16,810 --> 00:52:18,210
Go for that one.

1149
00:52:18,210 --> 00:52:21,079
Building optics needs optics experience.

1150
00:52:21,079 --> 00:52:23,520
If you want to actually build stuff,

1151
00:52:23,520 --> 00:52:26,079
well, there are many people in this institutes

1152
00:52:26,079 --> 00:52:28,099
or universities who work

1153
00:52:28,099 --> 00:52:30,500
in the mechanical fabrication departments

1154
00:52:30,500 --> 00:52:31,609
or electronics departments.

1155
00:52:31,609 --> 00:52:35,460
They just do PCB layouting all the time.

1156
00:52:35,460 --> 00:52:38,369
But this things do need sophisticated electronics

1157
00:52:38,369 --> 00:52:40,140
and this all custom built.

1158
00:52:40,140 --> 00:52:42,160
This is nothing you can buy of the shelf.

1159
00:52:42,160 --> 00:52:45,300
Nothing of it! Almost nothing.

1160
00:52:45,300 --> 00:52:46,500
And this means you might end up

1161
00:52:46,500 --> 00:52:48,819
with something equally cool.

1162
00:52:48,819 --> 00:52:51,099
It's not that you can have this one thing

1163
00:52:51,099 --> 00:52:53,829
and then BAM ten years later you will be

1164
00:52:53,829 --> 00:52:56,829
the laser-rocket scientist. You won't!

1165
00:52:56,829 --> 00:52:58,740
You might become one

1166
00:52:58,740 --> 00:53:01,819
and then even after 10 years,

1167
00:53:01,819 --> 00:53:04,010
you might realize this is not the thing

1168
00:53:04,010 --> 00:53:07,660
you want to do forever.

1169
00:53:07,660 --> 00:53:09,380
So I have to correct

1170
00:53:09,380 --> 00:53:10,900
the introduction in one point:

1171
00:53:10,900 --> 00:53:12,750
I'm no longer working there.

1172
00:53:12,750 --> 00:53:14,819
I recently left.

1173
00:53:14,819 --> 00:53:17,849
I'm now have my own company.

1174
00:53:17,849 --> 00:53:19,270
I'm still involved in these things.

1175
00:53:19,270 --> 00:53:21,710
I do calculations for this kinds of things,

1176
00:53:21,710 --> 00:53:23,520
but I'm not at an institute any more,

1177
00:53:23,520 --> 00:53:25,900
because I decided for example for me

1178
00:53:25,900 --> 00:53:29,190
that the contract conditions in this type

1179
00:53:29,190 --> 00:53:33,440
of scientific work are not of the type,

1180
00:53:33,440 --> 00:53:38,400
which I want to live with any more.

1181
00:53:38,400 --> 00:53:40,500
Like one year contracts.

1182
00:53:40,500 --> 00:53:49,220
<i>applause</i>

1183
00:53:49,220 --> 00:53:51,760
And so there are many ways
of being involved in this

1184
00:53:51,760 --> 00:53:53,970
and don't just... don't just
focus on the this!

1185
00:53:53,970 --> 00:53:56,710
Focus on what you really want to do and

1186
00:53:56,710 --> 00:53:59,440
you might end up in this

1187
00:53:59,440 --> 00:54:00,650
and if you don't,

1188
00:54:00,650 --> 00:54:03,563
well you do something equally cool.

1189
00:55:52,879 --> 00:55:56,730
All right! Questions?

1190
00:55:56,730 --> 00:56:04,800
<i>applause</i>

1191
00:56:04,800 --> 00:56:06,839
Herald: Okay, first of all

1192
00:56:06,839 --> 00:56:10,450
thank you for our daily dosis of lasers.

1193
00:56:10,450 --> 00:56:13,730
I have said... Ich hab keine Zeit...

1194
00:56:13,730 --> 00:56:16,589
cause we have really not much time left for Q&A,

1195
00:56:16,589 --> 00:56:19,530
so I'm first asking the signal angel,

1196
00:56:19,530 --> 00:56:21,410
if there are any questions from the internet,

1197
00:56:21,410 --> 00:56:25,880
because... was that a 2? 2! ok.

1198
00:56:25,880 --> 00:56:28,670
because this people can't ask questions afterwards,
soo...

1199
00:56:28,670 --> 00:56:31,329
Peter: I'll be all congress and
if you want to reach me

1200
00:56:31,329 --> 00:56:35,699
directly 7319 is this telephone.

1201
00:56:35,699 --> 00:56:39,030
Herald: Ok, the signal angel questions.

1202
00:56:39,030 --> 00:56:41,130
Signal A.: Yeah, the first question from the
internet was:

1203
00:56:41,130 --> 00:56:43,559
How strong the laser actually is

1204
00:56:43,559 --> 00:56:45,509
or if it could be any danger for something

1205
00:56:45,509 --> 00:56:47,380
in the vicinity?

1206
00:56:47,380 --> 00:56:48,440
Peter: Actually, no!

1207
00:56:48,440 --> 00:56:51,210
So we shoot up around 15 to 20 W

1208
00:56:51,210 --> 00:56:53,290
per laser beam.

1209
00:56:53,290 --> 00:56:55,579
If there was actually a plane flying through

1210
00:56:55,579 --> 00:56:58,410
our laser beam,

1211
00:56:58,410 --> 00:57:01,380
then nothing happens to the pilots.

1212
00:57:01,380 --> 00:57:03,040
They don't get blinded or what not,

1213
00:57:03,040 --> 00:57:06,290
because it's di... the beamsize at that altitude

1214
00:57:06,290 --> 00:57:09,069
is so big already.. they will of course look like:

1215
00:57:09,069 --> 00:57:10,710
"Errr what is this?"

1216
00:57:10,710 --> 00:57:12,720
And that's what we do not want,

1217
00:57:12,720 --> 00:57:14,470
because then they might push some other buttons

1218
00:57:14,470 --> 00:57:16,660
which they are not suppose to push.

1219
00:57:16,660 --> 00:57:17,750
<i>laughing</i>

1220
00:57:17,750 --> 00:57:20,270
If you of course work directly at the system,

1221
00:57:20,270 --> 00:57:21,200
you have to maintain it,

1222
00:57:21,200 --> 00:57:24,140
you open it, you have to align the lasers

1223
00:57:24,140 --> 00:57:27,559
and what not beyond there self aligning capabilities,

1224
00:57:27,559 --> 00:57:29,619
you do have to wear
all this protective laser goggles

1225
00:57:29,619 --> 00:57:32,140
and what not, because if you do...

1226
00:57:32,140 --> 00:57:35,359
if you don't you do have instant eye damage.

1227
00:57:35,359 --> 00:57:39,189
It is not... no its instant.

1228
00:57:39,189 --> 00:57:41,400
You might not see it instantly.

1229
00:57:41,400 --> 00:57:45,160
But the instant... it's there instantly, period.

1230
00:57:45,160 --> 00:57:48,290
So really, folks, don't experiment on this

1231
00:57:48,290 --> 00:57:49,589
laser stuff at home,

1232
00:57:49,589 --> 00:57:53,319
if you are not following basic
laser safety rules.

1233
00:57:53,319 --> 00:57:56,290
Not prying this things from the DVD burners

1234
00:57:56,290 --> 00:58:00,540
or no blue ray thingys "uuh does it really work?"

1235
00:58:00,540 --> 00:58:02,030
Just, just don't!

1236
00:58:02,030 --> 00:58:05,329
Your eyesight is not worth it. period.

1237
00:58:05,329 --> 00:58:08,080
It's not!

1238
00:58:08,080 --> 00:58:10,849
Herald: Please remember to cover
your still working eye!

1239
00:58:10,849 --> 00:58:13,500
Peter: Yeah... only look into the laser
beam

1240
00:58:13,500 --> 00:58:16,130
with your remaining eye.

1241
00:58:16,130 --> 00:58:17,489
Herald: The other question?

1242
00:58:17,489 --> 00:58:20,040
Signal A. :And the second question from the internet

1243
00:58:20,040 --> 00:58:21,940
was... It's actually commenting that,

1244
00:58:21,940 --> 00:58:24,230
this was a very cool concept already been used

1245
00:58:24,230 --> 00:58:26,520
and where do you see this going

1246
00:58:26,520 --> 00:58:28,849
in the next 10 years, so what's the outlook

1247
00:58:28,849 --> 00:58:31,820
for observation from the Earth's surface

1248
00:58:31,820 --> 00:58:33,250
in the next 10 years?

1249
00:58:33,250 --> 00:58:34,569
Peter: Oh, of course

1250
00:58:34,569 --> 00:58:36,089
the telescopes will get bigger and bigger.

1251
00:58:36,089 --> 00:58:38,170
The next generation of the telescope is coming up

1252
00:58:38,170 --> 00:58:39,660
in the 2020s.

1253
00:58:39,660 --> 00:58:41,369
The European Extremely Large Telescope

1254
00:58:41,369 --> 00:58:45,200
will be about roughly around
40 meters in diameter.

1255
00:58:45,200 --> 00:58:47,220
These are so huge they can't work in

1256
00:58:47,220 --> 00:58:49,250
seeing limited operation any more.

1257
00:58:49,250 --> 00:58:54,030
They do have to have laser AO all the time.

1258
00:58:54,030 --> 00:58:55,609
It will look similar to this.

1259
00:58:55,609 --> 00:58:57,349
So this is in that sense also

1260
00:58:57,349 --> 00:58:58,650
a technology demonstrator.

1261
00:58:58,650 --> 00:59:01,910
There will be a combined thing.

1262
00:59:01,910 --> 00:59:03,850
You may remember this diagram

1263
00:59:03,850 --> 00:59:06,260
with the one sodium laser in the middle

1264
00:59:06,260 --> 00:59:07,740
and the others outside.

1265
00:59:07,740 --> 00:59:09,319
So these combined things.

1266
00:59:09,319 --> 00:59:12,240
And then you can also imagine something,

1267
00:59:12,240 --> 00:59:13,869
that you probe different heights

1268
00:59:13,869 --> 00:59:14,910
in the atmosphere,

1269
00:59:14,910 --> 00:59:18,130
because you do have different turbulence layers

1270
00:59:18,130 --> 00:59:22,480
and all of these then have their own

1271
00:59:22,480 --> 00:59:23,750
deformable mirror.

1272
00:59:23,750 --> 00:59:25,660
So it's a very comp... gets a very complex
set,

1273
00:59:25,660 --> 00:59:29,460
a multi conjugate AO as it's called.

1274
00:59:29,460 --> 00:59:30,700
And then there are of course

1275
00:59:30,700 --> 00:59:33,940
new... there is research being done on

1276
00:59:33,940 --> 00:59:36,950
how to detect this wave front

1277
00:59:36,950 --> 00:59:38,089
most efficently.

1278
00:59:38,089 --> 00:59:40,380
And there is a so called thing called

1279
00:59:40,380 --> 00:59:42,410
the pyramid sensor.

1280
00:59:42,410 --> 00:59:44,230
You can look for that, also

1281
00:59:44,230 --> 00:59:46,220
we do have one in our system.

1282
00:59:46,220 --> 00:59:47,730
And this is very efficient.

1283
00:59:47,730 --> 00:59:49,680
So it takes much less photons

1284
00:59:49,680 --> 00:59:52,750
to get to the same signal to noise level.

1285
00:59:52,750 --> 00:59:55,740
This is active research and... well...

1286
00:59:55,740 --> 00:59:58,140
Every major telescope of course now has this.

1287
00:59:58,140 --> 01:00:00,400
And every big telescopes in the future

1288
01:00:00,400 --> 01:00:04,870
will have this all over the place.

1289
01:00:04,870 --> 01:00:09,270
Herald: Okay, we're completely out of time.
Again.

1290
01:00:09,270 --> 01:00:10,580
Again, so thank you very much.

1291
01:00:10,580 --> 01:00:12,070
Peter: Thank you!

1292
01:00:12,070 --> 01:00:17,491
<i>applause</i>

1293
01:00:17,491 --> 01:00:22,851
<i>postroll music</i>

1294
01:00:22,851 --> 01:00:29,000
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