Opto-Mechanical Design of ShaneAO: the Adaptive Optics System for the 3-meter Shane Telescope

TL;DR

This paper discusses the opto-mechanical design challenges and solutions for the ShaneAO adaptive optics system on a 3-meter telescope, focusing on stability, deformation, and thermal compensation techniques.

Contribution

It presents novel mechanical design strategies and analysis methods to ensure optical stability and performance in a Cassegrain mounted adaptive optics system.

Findings

Finite element analysis predicts gravitational deformations.

Thermal deformation compensation achieved without low CTE materials.

Design techniques maintain optical stability within error budgets.

Abstract

A Cassegrain mounted adaptive optics instrument presents unique challenges for opto-mechanical design. The flexure and temperature tolerances for stability are tighter than those of seeing limited instruments. This criteria requires particular attention to material properties and mounting techniques. This paper addresses the mechanical designs developed to meet the optical functional requirements. One of the key considerations was to have gravitational deformations, which vary with telescope orientation, stay within the optical error budget, or ensure that we can compensate with a steering mirror by maintaining predictable elastic behavior. Here we look at several cases where deformation is predicted with finite element analysis and Hertzian deformation analysis and also tested. Techniques used to address thermal deformation compensation without the use of low CTE materials will also be discussed.