Characterizing the vibration environments of the Gemini telescopes

Disturbance Modelling for Minimum Variance Control in Adaptive Optics Systems Using Wavefront Sensor Sampled-Data

“…For example, the mechanical vibration that is caused by excitations of on-site instruments usually exhibits narrow-band high-frequency components, the structural responses of large telescopes are within a low frequency band of natural resonances, and the atmospheric turbulences exhibit a (roughly) constant component below a corner frequency and a roll-off at high frequency on a Zernike basis [ 25 ]. In addition, the compensation of tip and tilt are one of the main tasks of AO [ 2 , 23 , 26 ]. Hence, an adequate identification of the disturbance source model is of great interest, which, in turn, allows for the development and implementation of effective control techniques.…”

“…Currently, the Large Binocular Telescope (LBT) in Arizona, USA, reaches a combined effective aperture of m, whilst the Gran Telescopio Canarias (GTC) in the Canary Islands, Spain, reaches an effective aperture of m. This kind of modern telescopes is used for deep universe exploration as well as sharp high-definition images. However, the attainment of such images is subject to the inherent effects of the atmosphere and the vibrations of different equipment that are part of the telescope, see e.g., [ 2 ].…”

“…Adaptive optics (AO) is an optical technique that is used to improve astronomical images by compensating the effect of wavefront distortions caused by atmospheric turbulences and mechanical vibrations [ 3 , 4 ]. AO systems are very sensitive to vibrations acting in the propagation of the light [ 2 , 5 , 6 ]. Mechanical vibrations are typically induced by wind or elements within the instrumentation of the system, such as fans and cooling pumps.…”

“…Mechanical vibrations are typically induced by wind or elements within the instrumentation of the system, such as fans and cooling pumps. Hence, the modelling and mitigation of disturbances are a subject of increasing importance in many observatories [ 2 , 7 , 8 , 9 , 10 ]. This mitigation is achieved by deforming a deformable mirror (DM) in order to compensate the optical aberrations that are measured by a wavefront sensor (WFS), which, in turn, implies the need for both an accurate model of the complete AO system and adequate controllers.…”

Management of equipment vibration for extremely large telescopes

“…ESO undertook a major program at the very large telescope (VLT) to minimize vibration and to define requirements for instruments 1,2 and identify the best low-vibration cooling options for future instruments. 3 Teams at Gemini also undertook a large program to find vibration sources, 4 finding the biggest contributing sources to image degradation were instrument cryocoolers 5 and cooling fans. Similar programs have been run at Keck 6 and the Large Binocular Telescope.…”