All Figures

Figure 1: Composite photograph of the AMBER instrument in the integration room of the Laboratoire d'Astrophysique de Grenoble in 2003. The instrument was complete but for its enclosure and for the beam commutation device. Some integration and test tools are also still present on the table. The beams (white lines) arrive in the bottom left of the picture and travel from the left to the right. They are split spectrally by dichroïcs in K, H, and J bands (respectively red, green, and blue from left to right) before being fed into single-mode optical fibers that filter each beam spatially. After the spatial filters, the bands are merged together by a symmetrical set of dichroïcs, then travel right to left through cylindrical optics and a periscope, and is finally focused on the entrance slit of the cryogenic spectrograph in the upper left corner. The 1600 Kg AMBER table is 4.2 by 1.5 m and supports about 300 Kg of optical and mechanical equipment.

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In the text

Figure 2: The basic concept of AMBER. First, each beam is spatially filtered by a single-mode optical fiber. After each fiber, the beams are collimated so that the spacing between the output pupils is non redundant. The multiaxial recombination consists in a common optics that merges the three output beams in a common Airy disk containing Young's fringes. Thanks to a cylindrical optics anamorphoser, this fringed Airy disk is fed into the input slit of a spectrograph. In the focal plane of the spectrograph, each column (in the figure, but in the reality each line) of the detector contains a monochromatic image of the slit with 3 photometric (P1, P2, P3) zones and one interferogram (IF). In this figure, the detector image contains a view rotated of of the AMBER real-time display showing three telescope fringes, in medium-resolution between 2090 and , on the bright Be star Arae. The three superimposed fringe patterns form a clear Moiré figure because, in that particular case, the three OPDs were substantially different from zero during the recording. Note that the vertical brighter line indicating the Br emission line.

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In the text

Figure 3: Raw detector image from amber obtained in the three-telescope low-resolution mode on the star  Bootis in April 2006. The stellar signal is spectrally dispersed in the vertical direction and each (pair of) detector line contains a spectral channel. The rows of K band and H band occupy respectively the upper and the lower half of the screen. From left to right, the first, second, and fourth columns represent the photometric beams for the each one of the free telescopes, while the third column contains the interferometric signal, with three superimposed fringe systems.

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In the text

Figure 4: Exploration of the u-v plane using spectral coverage. The two figures represent the typical fringed visibility function as a function of u and v, as produced by a binary. On the left we have the u-v tracks obtained with a single spectral channel and 10 hours of observations with UT1-UT3-UT4. On the right, we represent the u-v coverage obtained from 1.05 to 2.4 microns with only one snapshot observation with the same telescopes. As demonstrated by (Millour et al. 2007), the constraints on the binary angular separation are similar for the left and right u-v coverages, but in the spectrally resolved case we obtain the spectra of the components in addition.

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In the text

	Figure 5: Data used for spectral calibration. Top: source spectrum ( ); Middle: the calibrator star flat spectrum (shifted by -0.5); Bottom: the reference Gemini spectrum (shifted by -1). Note the atmospheric water-vapor doublets at 2.01 and used for calibration in K-band medium-resolution observations.
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In the text