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In the same section :
General views of AMBER
"Making of" of the Amber movie

Guided tour of the AMBER instrument
Monday 26 January 2004, by Florentin Millour

Amber is a mid-infrared instrument to use 3 telescopes ofthe VLTI at the same time, creating interference fringes from the light of a star.

Here I present the differents elements of the experiment AMBER and the related images taken during operation in Grenoble.

First of all, I put here a photo of the thermally controlled room where AMBER was tested in Grenoble. You can see the liquid nitrogen can used to cool down the detector and spectrograph (30kg of liquid nitrogen per day !)

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The control room is used to control the experiment from ouside because of the restricted access in the experiment room.

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First, to understand the complexity of this machine, I put a global photo of AMBER :

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All the elements have a separate function which I will discribe briefly. For more details, see the complete description of the instrument on the site.
First of all, the CAU, or Calibration and Alignment Unit which is used for internal calibration of the instrument. You can see the three holes corresponding to the telescopes beams going from the VLTI when AMBER will be installed at paranal.

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Then there are some shutters and neutral density filters that can be put in the way of the beams.

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You can find after a 45 degrees mirror called Bypass, which is used for alignment purposes.

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After that there are the polarizers who are used to artificially increase the useful measurment in AMBER, namely the visibility.

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Then you can find just after the polarizers the MCS plates which are used with the CAU to calibrate the instrument.

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After that, there is a big part of Amber, the spatial filters, which are used to make reliable calibration on the observed star. You can see in that photo the three spatial filters corresponding to the three infrared chromatic bands J,H and K.

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Here is an example of the structure of one of the three spatial filters : each of the three beams is injected to an optical fiber and transmitted to the other side of the instrument where the three beams are recombinated.

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In the J and H bands, the chromatic effect of the atmosphere cannot be neglected, that is why a system, the ADC (or Atmospheric ...) reshape the beam before injecting in the fibers.

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The light is then sent to a set of cylindrical mirrors to anamorphoze the beams and to send them to the spectrograph.

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After this operation, the beam is sent to the spectrograph with a periscope and the fringes are made on the detector (The golden box)

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