The Spectrograph Esopo: Scientific Goals, High-Level Requirements, And Introduction To The Design

In this paper we present the Medium Resolution Spectrograph ESOPO, an instrument designed and built for the 2.1 m Telescope at the Observatorio Astronomico Nacional at San Pedro Martir. We discuss the Scientific Goals and the High Level Requirements necessary to translate these goals to optical, mechanical and control specifications. We make an introduction to its conceptual dual-arm design. The optical design is based on a non-classical configuration. The gratings are illuminated in a conical mode working in a quasi Littrow configuration which has the advantage of optimizing the efficiency and the pupil area on the grating. We show here the results of an experimental evaluation of the concept. The optical design, mechanical structure, slit-mask and acquisition system, control systems, and a study of thermal compensators, are discussed briefly, references to more extended contributions in these proceedings are made. The management schematics of the project are briefly discussed.