The LINC-NIRVANA fringe and flexure tracker: cryo-ambient mechanical design

Thomas Bertram; Harald Baumeister; Werner Laun; Christian Straubmeier; Steffen Rost; Yeping Wang; Andreas Eckart

doi:10.1117/12.671378

28 June 2006 The LINC-NIRVANA fringe and flexure tracker: cryo-ambient mechanical design

Thomas Bertram, Harald Baumeister, Werner Laun, Christian Straubmeier, Steffen Rost, Yeping Wang, Andreas Eckart

Proceedings Volume 6268, Advances in Stellar Interferometry; 62683L (2006) https://doi.org/10.1117/12.671378
Event: SPIE Astronomical Telescopes + Instrumentation, 2006, Orlando, Florida , United States

Abstract

The correction of atmospheric differential piston and instrumental flexure effects is mandatory for interferometric operation of the LBT NIR interferometric imaging camera LINC-NIRVANA. The task of the Fringe and Flexure Tracking System (FFTS) is to detect and correct these effects in a real-time closed loop. Being a Fizeau-Interferometer, the LBT provides a large field of view (FoV). The FFTS can make use of the large FoV and increase the sky coverage of the overall instrument if it is able to acquire the light of a suitable fringe tracking reference star within the FoV. For this purpose, the FFTS detector needs to be moved to the position of the reference star PSF in the curved focal plane and needs to precisely follow its trajectory as the field rotates. Sub-pixel (1 pixel = 18.5 micron) positioning accuracy is required over a travel range of 200mm x 300mm x 70mm. Strong are the constraints imposed by the need of a cryogenic environment for the moving detector. We present a mechanical design, in which the Detector Positioning Unit (DPU) is realized with off-the-shelf micro-positioning stages, which can be kept at ambient temperature. A moving baffle will prevent the intrusion of radiation from the ambient temperature environment into the cryogenic interior of the camera. This baffle consists of two nested disks, which synchronously follow any derotation - or repositioning trajectory of the DPU. The detector, its fanout board and a filter wheel are integrated into a housing that is mounted on top of the DPU and that protects the FFTS detector from stray light. Long and flexible copper bands allow heat transfer from the housing to the LINC-NIRVANA heat exchanger.

Citation Download Citation

Thomas Bertram, Harald Baumeister, Werner Laun, Christian Straubmeier, Steffen Rost, Yeping Wang, and Andreas Eckart "The LINC-NIRVANA fringe and flexure tracker: cryo-ambient mechanical design", Proc. SPIE 6268, Advances in Stellar Interferometry, 62683L (28 June 2006); https://doi.org/10.1117/12.671378

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available