Experiences with global laser tracker alignment of the 32.5-m LMT primary surface

Andrea Leon-Huerta; Maribel Lucero Alvarez; Emilio Hernández Rios; Lizeth Cabrera Cuevas; David Castro Santos; Carlos Tzile Torres; Josefina Lázaro Hernández; David M. Gale; Gopal Narayanan; David R. Smith; Grant Wilson

doi:10.1117/12.2056856

28 July 2014 Experiences with global laser tracker alignment of the 32.5-m LMT primary surface

Andrea Leon-Huerta, Maribel Lucero Alvarez, Emilio Hernández Rios, Lizeth Cabrera Cuevas, David Castro Santos, Carlos Tzile Torres, Josefina Lázaro Hernández, David M. Gale, Gopal Narayanan, David R. Smith, Grant Wilson

Author Affiliations +

Proceedings Volume 9151, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation; 91513Q (2014) https://doi.org/10.1117/12.2056856
Event: SPIE Astronomical Telescopes + Instrumentation, 2014, Montréal, Quebec, Canada

Abstract

The Large Millimeter Telescope Alfonso Serrano (LMT) currently has a primary reflector of 32.5m diameter composed of 84 panels, each having a surface area of approximately 10 square meters. Each panel is supported on four electromechanical actuators, allowing for the correction of tip-tilt, piston and twist. The actuators are designed to perform active surface compensation of gravity deformations as a function of elevation. Following the setting and installation of individual panels, an approximation for global alignment of the primary surface is carried out using a total station. An RMS error of 200 - 500μm is expected for this process. Final global alignment is conducted using holography at 12GHz for elevations corresponding to the location of geostationary sources. As an intermediate alignment option for the antenna at zenith, the use of a laser tracker has been explored. Global alignment of a large primary surface with a laser tracker presents the common problems related to the contact measurement of a large object in a non-metrology environment. Key issues are the stable location of fiducial points and the relatively slow data collection rate. Additionally the high altitude site (4600m, 15000ft) with mean temperatures around zero degrees Celsius, presents a challenge for our interferometer-equipped trackers. In this paper we present first results using a tracker located near the antenna vertex, and mechanical adjusters in place of actuators. An RMS error of around 100μm was achieved. Limiting factors included inadequate fiducials and slow mapping speed. Proposals for reduced data collection times and improved metrology robustness are presented.

Citation Download Citation

Andrea Leon-Huerta, Maribel Lucero Alvarez, Emilio Hernández Rios, Lizeth Cabrera Cuevas, David Castro Santos, Carlos Tzile Torres, Josefina Lázaro Hernández, David M. Gale, Gopal Narayanan, David R. Smith, and Grant Wilson "Experiences with global laser tracker alignment of the 32.5-m LMT primary surface", Proc. SPIE 9151, Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation, 91513Q (28 July 2014); https://doi.org/10.1117/12.2056856

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