The opto-mechanical alignment procedure of the VLT Survey Telescope

TL;DR

This paper details an alignment procedure for the VLT Survey Telescope that uses specialized tools and laser-based methods to precisely align optical components independently of their mechanical manufacturing precision.

Contribution

It introduces a novel opto-mechanical alignment method that does not depend on the mechanical accuracy of the telescope components, using laser-based tools for precise optical axis determination.

Findings

Successful alignment of primary mirror, secondary, and correctors.

Alignment procedure independent of mechanical manufacturing tolerances.

Enhanced optical performance of the telescope.

Abstract

The VLT Survey Telescope is a f/5.5 modified Ritchey-Chretien imaging telescope, which is being installed at the ESO-Paranal Observatory. It will provide a one square degree corrected field of view to perform survey-projects in the wavelength range from UV to I band. In this paper we describe the opto-mechanical alignment procedure of the 2.61m primary mirror, the secondary and correctors lenses onto the mechanical structure of the telescope. The alignment procedure does not rely on the mechanical precision of the mirrors. It will be achieved using ad-hoc alignment tools, described in the paper, which allows the spatial determination of optical axes (and focuses where necessary) of the optical components with respect to the axis defined by the rotation of a laser beam mounted on the instrument bearing.