Integration and testing of the GRAVITY infrared camera for multiple telescope optical beam analysis

Gordo, Paulo; Amorim, A.; Abreu, Jorge; Eisenhauer, F.; Anugu, Narsireddy; Garcia, Paulo J. V.; Pfuhl, O.; Haug, M.; Sturm, E.; Wieprecht, E.; Perrin, G.; Brandner, W.; Straubmeier, C.; Perraut, K.; Naia, M. Duarte; Guimarães, Margarete C.

doi:10.1117/12.2056572

Cited by 2 publications

(8 citation statements)

References 2 publications

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“…The large bandwidth of the diode allows to track image jitter of up to ~1kHz. Located behind the laser tracker module, the acquisition camera [5], [6] of GRAVITY monitors slow image drifts on sky and at the same time monitors the pupil position.…”

Section: The Fiber Couplermentioning

confidence: 99%

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The fiber coupler and beam stabilization system of the GRAVITY interferometer

et al. 2014

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We present the installed and fully operational beam stabilization and fiber injection subsystem feeding the 2nd generation VLTI instrument GRAVITY. The interferometer GRAVITY requires an unprecedented stability of the VLTI optical train to achieve micro-arcsecond astrometry. For this purpose, GRAVITY contains four fiber coupler units, one per telescope. Each unit is equipped with actuators to stabilize the telescope beam in terms of tilt and lateral pupil displacement, to rotate the field, to adjust the polarization and to compensate atmospheric piston. A special roof-prism offers the possibility of on-axis as well as off-axis fringe tracking without changing the optical train. We describe the assembly, integration and alignment and the resulting optical quality and performance of the individual units. Finally, we present the closed-loop performance of the tip-tilt and pupil tracking achieved with the final systems in the lab..

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Section: The Fiber Couplermentioning

confidence: 99%

“…The pupil tracker of the acquisition camera [5] provides the feedback for the pupil stabilization loop. The optical and mechanical development of the acquisition camera is the work-package of the University of Lisbon.…”

Section: Sensormentioning

confidence: 99%

The fiber coupler and beam stabilization system of the GRAVITY interferometer

et al. 2014

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“…Liquid Nitrogen (LN2) is one of the most common cooling agents in near infrared astronomical instruments. For example, acquisition camera (Gordo et al 2014) is a multiple telescope's near infrared beams analyzing instrument which is refrigerated with LN2. The advantages of keeping near infrared instruments at low temperatures are to minimize detector's readout and dark noises and it also reduces thermal emissions in the near infrared originated from the instrument structure.…”

Section: Introductionmentioning

confidence: 99%

“…The acquisition camera, a sub instrument of GRAVITY (Eisenhauer et al 2011), is designed to operate at LN2 temperatures. GRAVITY is a beam combiner instrument, which combines four very large telescopes (8 m) beams of European Southern Observatory (ESO) and delivers very precise astrometric measurements of stars positions in the vicinity of Milky Way Galactic Center supermassive Black Hole (Gordo et al 2014). The acquisition camera instrument has been built (optical alignment and assembly) at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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A Low Cost Auto-filling and Refrigeration Rate Regulated Liquid Nitrogen Controller for Near Infrared Instruments

Anugu

Amorim

Garcia

et al. 2018

UPjeng

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Liquid Nitrogen is one of the key refrigerating elements in cooling near infrared science instruments to reduce the dark, readout noises and thermal emissions in the near infrared originated from the instrument structure. Usually, a small liquid nitrogen tank connected to the near infrared instrument is auto filled from a large Dewar in order to maintain required low temperatures during the experiment for several hours. The detectors used in these instruments are quite expensive and they need to be cooled down steadily (< 2K/min) to avoid mechanical damage. The steady state cooling of the detector is the key requirement to be considered while cooling down the detector. In this paper, a controller is developed to auto-fill the liquid nitrogen tank and also to keep the refrigeration rate of the detector below 2K/min. A systematic survey of auto-filling controllers is studied. The auto-filling of liquid nitrogen from Dewar to tank is implemented with a standard on-off controller. To address the critical refrigeration rate of the detector, two approaches are studied: a) by fixed time pumping; b) by feedback the detector cooling rate. In this work we have used inexpensive equipment to develop this controller. It is very successfully used for GRAVITY acquisition camera, a near infrared instrument for European Southern Observatory. This controller has been stable and efficient for our experiment. This low cost controller can be used for any student laboratory and research.

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Integration and testing of the GRAVITY infrared camera for multiple telescope optical beam analysis

Cited by 2 publications

References 2 publications

The fiber coupler and beam stabilization system of the GRAVITY interferometer

The fiber coupler and beam stabilization system of the GRAVITY interferometer

A Low Cost Auto-filling and Refrigeration Rate Regulated Liquid Nitrogen Controller for Near Infrared Instruments

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