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https:/.../30c3-5311-en-lasers_in_space_h264-iprod.mp4

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    Welcome to our next talk.
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    This is Anja Kohfeldt. And she will be talkin about "Lasers in Space".
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    Please give her a warm round of applause.
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    Anja: Ja, hello everybody I also would like to welcome you to my talk.
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    As the Angel already said.
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    It is about lasers in space
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    and they more than just: "Pew! Pew!"
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    So that's what I want to talk about.
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    I'm a scientist at the Ferdinand-Braun-Institut in Berlin.
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    And I am a member of the Quantus Project group.
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    The Quantus Project has the main goal, to build an optical atom interferometer, in space.
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    And there we started at the drop tower in Bremen and now we are heading toward our sounding rocket
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    which will be launched in november next year.
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    In order to build this atom interferometer, we have to cool down atoms
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    and for that we semiconductors(?) or we need lasers, at a specific wave length.
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    And my job in this project is to build these laser modules.
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    So now you know what I'm doing.
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    My motivation for this talk today is:
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    At first lasers are cool!
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    I think everybody will agree to that.
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    I hope so.
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    In the past years there have been a lot of projects concerning lasers.
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    For example building lasers cutters or building laser projectors, or pimping you laser pointer to laser gun, burning stuff.
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    There are some pictures I found on the web.
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    And than there is the space side.
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    This whole space stuff got more and more affordable in the previous years.
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    There is more and more private activity in the space sector.
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    For example private companies building launching systems.
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    But there are also a lot of student and university programs to build there own satellite to make science in space, science in micro gravity.
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    And I think when we just follow this development there also will be
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    more, yeah, there also will be some hacking possible in space in the next years.
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    There is also a personal motivation.
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    Whenever I tell somebody that I am building lasers for space applications, there is always this:
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    "Oh, you are building orbital death lasers!"
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    No, I don't.
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    [Someone booing in the audience, causing the others to breaks out into laughter.]
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    Actually I'm very happy that I don't do that.
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    This talk will be about other applications of lasers in space.
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    When you google lasers in space, you find a lot pictures like that.
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    And they are beautiful. They really are.
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    They have lasers, they have space.
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    But I won't talk about that, because these lasers are on earth.
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    They are guiding the stars very often or laser shows. Both applications.
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    Very useful, very nice pictures. Here they are.
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    Okay? Nice.
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    So, I would like to talk about a little laser 101.
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    Telling what is a laser? What can you do with a laser? What is space?
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    And, well, as I said already, the applications of it.
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    Lasers. Laser: "light amplification of stimulated emission of radiation"
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    Yeah, ok. We knew that.
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    It's a device emitting monochromatic and coherent light.
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    And that's nothing else but:
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    Light with the same wavelength, in the same direction and the same polarization.
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    With that properties you can focus photons on a very, very small area,
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    because there are lot of photons doing the same thing.
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    And that's why you have a very high power density
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    and that is why you can use lasers for example for welding, for cutting
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    or for delivering data over very, very long distance
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    What do you need to build a laser?
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    You need active medium.
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    This active medium, or the electrons in this active medium, are stimulated by a pump.
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    This either an optical pump or an electrical pump or whatever pump.
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    And you need a resonator to sort the right photons.
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    And when it comes to the classification of lasers, you basically vary the active medium.
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    So for example there are solid state lasers, where you use a crystal.
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    A very good example for a solid state laser is the neon doped XXX XXX laser. The YaC Laser, as we are used to call that.
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    This laser or this type of laser is used industry, but you also find it in laser-light-shows.
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    There are a lot of applications for that.
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    In contrast there are semi-conductor lasers.
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    They are a lot smaller.
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    You see, the green one on the left is the YaC Laser, in the center you find the semiconductor laser.
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    They a are a lot smaller, they are cheaper, they are more efficient.
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    And you can tune the wavelength over a certain range.
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    As an example here, there is the indium gallium nitride laser, which you will find in you Blue-Ray-Player
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    or the aluminium gallium arsenide diode, which is commonly used in DVD-Players, and stuff like that.
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    I think everybody owns at least one of them.
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    There are gas lasers.
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    For example helium-neon-lasers.
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    The helium-neon-lasers built in the current wave mode.
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    And it's now used, for example for calibration or in schools.
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    And the CO2 laser is one with very, very high power density.
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    It's a pulse laser, used for example for welding.
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    And there are the dye lasers, which can tune the wave length on a very, very long range.
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    They are very often used for spectroscopy, for example.
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    So whatever you want to do, you have to chose your laser your laser type with your application.
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    And they vary a lot in their output power, in there mode, whether they are pulsed or not pulsed
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    and their wavelength, but also in their size and complexity, yeah.
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    And you just have to chose the right one.
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    This is important especially when we are going to space.
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    Here are some common applications for lasers.
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    You use them in measuring, in optical data transmission,
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    they are used in the multimedia sector and also in the production sector.
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    But not only at home, or industrial or in medicine, but also in space.
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    So space, here we are.
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    The common definition of space is: "Hundred kilometres above the sea level."
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    But whenever there is, for example an Apollo astronaut, when they are talking about space,
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    they are talking about 50 miles, which is an older definition of space, based in the US.
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    You can go to space via satellite, you have the space station
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    and sometimes at the space station you have an operator, like a person operating your experiment. Might be useful.
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    There have been orbital experiments. Especially the times with a space shuttle.
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    And there are sounding rockets, which are rockets going up up to approximately a thousand kilometres max,
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    and falling down, but in the meantime you can perform experiments in zero gravity.
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    Why do you want to go to space?
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    Well, there are a lot of reasons.
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    For example the observation of distant galaxies, the earth weather,
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    there are communication satellites, just to transfer data,
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    you can or you want to perform science up there.
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    For example because of the lack of gravity or the lack of atmosphere.
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    There is navigation and there is also the military purpose, you can't deny that.
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    But it's not that easy going to space.
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    Whenever you want to go there, there are a lot of restrictions.
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    For example the size and the weight.
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    When you want to launch something into space, you have costs approximately four to five thousand dollar a kilo.
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    Although this price is decreasing, it's still high enough.
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    You are very limited in you power consumption, cause you don't have, i mean
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    it's a closed system, right? You have you solar panel, but that's it.
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    And sometimes some other energy sources, which may disappear after a while.
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    Everything you want to send up there has to survive the launch and sometimes it has to survive the landing.
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    When it's coming back to earth, there might be applications where you might use that.
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    Very often there is no operator.
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    Like no one pressing buttons. So everything has to run autonomously.
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    And your stuff needs quite a long life time, cause you don't want to switch parts once a year on a satellite.
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    So you normally don't do that.
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    So, as I said in the beginning, I'm a scientist.
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    And this is a lab.
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    It's not my lab, I'm very happy about that.
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    But this is an experiment quite close to that what we want to do.
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    And as you might assume, this is not a good idea to launch that.
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    It won't hold.
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    It won't survive the launch and probably it won't work up there.
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    So what did we do? You have to choose an appropriate technology.
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    That's why we are using semiconductors for exmaple.
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    They are much smaller, they are much more energy efficient.
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    You have to space qualify all the components you are using.
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    You have to take care of the materials you are using.
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    You can't use whatever a XXX for example, because you have this out gassing problem.
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    Your device has to operate in vaccum, very often at least.
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    You have to minimize everything.
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    You want to fix every part.
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    You don't want to much movable parts. Because there won't be anybody to fix your setup, afterwards.
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    And you have to work in a clean environment, when you integrate something.
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    Dust is a problem, for example.
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    You don't want to have any particles around.
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    You have to test and characterize everything and once again and once again.
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    And you have to document everything. Like more than everything.
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    So this are some pictures of my lab.
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    On this side, you see a characterization setup.
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    In our lab, it's not clean room, yet!
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    We are not working on a satellite mission, it's just a sounding rocket.
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    But we wear these funny lab coats and funny hats.
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    So maybe you see that person there in the middle, it's a colleague of mine.
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    If you see that: "Hello!" :)
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    And on the other side it's the integration station, of our lasers.
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    And some setup around to characterize everything.
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    So, just to show the result of our effort.
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    It's a semiconductor based master oscillator power amplifier, of the size of that.
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    Its like 8 centimetres long and 2.5 centimetres wide.
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    It has nor movable parts and it's a specific wavelength, cause we need that for our application.
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    We want to cool down rubidium.
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    It has an output power greater than 1.2 Watts.
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    So, how much is that?
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    Well, a laser pointer has a 1 milliwatt.
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    An illegal laser pointer has 100 milliwatt.
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    And this is ten times stronger.
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    And the efficiency we have now is 22%.
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    When we fuck of the wavelength, when we don't care about that at all, than we can achieve an even higher efficiency and a higher output power.
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    But in our application the wavelength is mandatory.
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    So now, when it comes to testing you need some documents telling you, what to test.
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    And how to test and so on.
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    So, there are a couple of standards and most of the standards are based in the military sector.
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    The standard which is very important for us is, for example, the MIL-STD-883.
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    Which describe test methods of micro circuits and thats a really huge document.
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    It's about 630 pages thick.
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    And it describes the purpose of a test, the apparatus, the test conditions and the procedure and the failure criteria
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    ...of environmental tests, of mechanical tests and of electrical tests.
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    So in this picture down there you see our laser system.
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    The silver cube is the entire laser system, we have in our experiment.
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    It contains 8 lasers and a spectroscopy module and a switching module.
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    And this setup is on a shaker.
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    So here we are performing a random vibration test on acceptance level.
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    And we passed. So I'm very, very happy about that.
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    And of course there a lot more tests we have to perform.
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    But it looks good, so far.
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    So now we have our hardware, what else can we do with that than building weapons and atom interferometers?
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    Of course we have the interferometer is a very common application.
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    Just to name the LIDAR system, it's a combination of radar, but with light.
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    And this one is used for as alterometer(?) for example.
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    Or to map surfaces. For example of some distant planets, of the moon, of the earth, of whatever.
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    Systems are sending out a beam
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    and they are analysing the reflected beam concerning the phase shift
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    and than they now how far the reflector is away.
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    And with that you can measure very precisely distance.
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    You need that for example in docking operations. In the picture up there you see the ATV satellite docking station.
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    I think it was in 2007. You have several other satellites, for example mapping the planet.
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    Ant there is also another mission I would like to point out.
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    This is the LISA mission, which wants to point out gravitational waves.
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    Unfortunately the LISA project cut down. And now it's just LISA Pathfinder.
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    A proof-of-concet mission, which is scheduled in 2015.
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    But there are of course a lot of more applications, I just picked out some which I fond interesting.
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    Spectroscopy is also a very nice application.
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    When it comes to spectroscopy, you analyse the beam concerning of the absorption or reflecting photons coming back.
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    So you are also sending up a laser beam and it comes back and you simply look what is coming back.
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    And with that you can analyse matter with a chemical composition of matter around.
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    For example on Curiosity, the Mars rover they are looking for methane gas by spectrography.
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    So they have at least two spectrometers on board of this little guy.
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    And another application which gains more and more importance in space are optical atomical clocks.
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    It's a time keeping device, but optical clocks operating with lasers are even more precise than radio operated ones.
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    And there are some new generations of optical atomic clocks, cause they are even more precise in space.
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    For example there is the ACES mission, which is a french mission, which was scheduled at the end of this year.
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    Unfortunately a newer launching date, but I think it won't be launched next year.
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    Maybe you know even more than I do.
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    And there is also another mission called X quest, which is still in preparation.
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    So, this is everything I have on measurement.
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    Free space optical communication is maybe an application3, most of you know what it is.
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    You have your optical carrier, the laser beam,
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    and you modulate you data either with phase shifting or with binary on-off keying.
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    The binary on-off keying is the most common one.
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    Compared to the commonly used RF-transmission you can go over longer distances,
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    it needs less power and you have a higher transmission rate.
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    Still it depends on the weather and the atmosphere on earth, when you want transfer data down to earth.
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    As an example I can name the Laser Communication Terminal.
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    It's build from TISAD(?) and it was first tested on the satellite ARTEMIS.
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    It had a downlink and an intersatellite bandwith of 50 Mbps. This was in 2001.
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    In 2008 there was another inter-satellite connection between XXX and XXX and they received 5.5 Gbps.
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29:22

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