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Figure 1: Scheme of the AMBER configuration: (1) multiaxial beam combiner; (2) cylindrical optics; (3) anamorphosed focal image with fringes; (4) "long slit spectrograph''; (5) dispersed fringes on 2D detector; (6) spatial filter with single mode optical fibers; (7) photometric beams. |
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Figure 2: General implementation of AMBER. The top scheme shows the light path from the VLTI to the detector. Detailed configuration below. The VLTI beams arrive in the lower left corner. OPM-CAU: Calibration and Alignment Unit. OPM-BCD: beam inverting device (Petrov et al. 2003). OPM-POL: polarization selecting device. OPM-SFK (SFH, SFJ): spatial filters for the K-, H-, and J-bands. OPM-ADC: corrector for the atmospheric differential refraction in H and J. OPM-ANS: cylindrical afocal system for image anamorphosis. OPM-OSI: periscope to co-align the warm and the cold optics. OPM-BYP: movable bypass directly sending the VLTI beams towards technical tools or towards the spectrograph to check VLTI alignment and acquire complex fields. SPG-INW: input wheel with image cold stop and diaphgram inside the spectrograph (SPG). SPG-PMW: pupil mask wheel. SPG-IPS: beam splitter allowing the separation between interferometric and photometric beams. SPG-DIU: light dispersion (gratings or prism). SPG-CHA: SPG camera. DET-IDD: chip. SPG-CSY and DET-CSY: cryostats of the SPG and of the Hawaii detector (DET). During final operation, the two cryostats are connected by a cold tunnel and share the same vacuum. |
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Figure 3: Picture of the AMBER instrument at the end of the integration at Paranal in March 2004 (by A. Delboulbé, LAOG). |
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Figure 4: Pictures of the K-spatial filter entrance. Left (picture by Y. Bresson, OCA): the three beams meet the dichroics and the parabolic off-axis mirrors before the injection through the Si birefringent single-mode fibers; Right (picture by A. Delboulbé, LAOG): the optical configuration is repeated at the exit of the fibers. Diaphragms control the beam size at the exit of the fibers and shutters select the interferometric arms. |
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Figure 5:
Left: illustration of photometric images (extreme) and interferometric image ( center) produced with the artificial source (H-band,
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Figure 6:
Above is the surface profile as measured with the micro-sensor of SAVIMEX on a test element: maximum roughness of 60 nm PTV and rms roughness of Ra 6.5 nm and Rq 8.2 nm; Below is the picture of the mirror allowing the manufacturing of the three injection optics in the SFJ as observed through the microscope (field of
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Figure 7: AMBER pupil configuration in J, H, and K with no anamorphosis. |
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Figure 8: Illustration: simulated optical transfer function (OTF) in which the coherent and incoherent energy peaks are not completely separated. The pupil separation is chosen such that the fringe peak center is not affected by the incoherent peak. |
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Figure 9: Optical design of the SPG. For the acronym definition see Table 2. |
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Figure 10: Physical overview of the AMBER detector hardware. |
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Figure 11: Image with the CAU light: dark current, photometric beams (P*), and interferometric beam (In). |
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Figure 12: Calibration and Alignment Unit (CAU). |
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Figure 13:
Relative axial rotation of one ADC system relative to the other one at ![]() ![]() |
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Figure 14:
Combined optical and positioning errors of the ADC. The spots represent the impacts of the beam for 3 wavelengths inside each band, J (black spots) and H (white spots), for 3 values of the zenithal angle z, and taking into account the following errors: prism angles manufacturing, error on the prism gluing, sensitivity of the axial rotation of the two glued prisms respective to the first one, tip/tilt of this rotation axis, tip/tilt of the 3-prisms assembly, sensitivity of the 360![]() |
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Figure 15:
Contributions to the throughput and instrumental contrast (
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Figure 16:
Left: spot diagram at the SFK fiber entrance using the light from the VLTI. The coupling loss ratio is about 2.6%. Right: spot diagram at the spectrograph entrance in the K-band. The associated Strehl ratio is 0.92. This optical quality leads to a differential WF rms error of ![]() ![]() |
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Figure 17:
Above: residual WF aberration at liquid nitrogen temperature as measured with external optical elements (
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