CARMENES. II: optical and opto-mechanical design Seifert, Walter Sánchez Carrasco, Miguel A. Xu, Wenli Sánchez Blanco, Ernesto Cárdenas, Concepción Becerril, Santiago Feiz, Carmen et al. Paper 8446-114 of Conference 8446 Date: Sunday, 01 July 2012 CARMENES is a fiber-fed high-resolution échelle spectrograph for the Calar Alto 3.5m telescope. The instrument is built by a German-Spanish consortium under the lead of the Landessternwarte Heidelberg. The search for planets around M stars with a radial velocity accuracy of 1 m/s is the main focus of the science planned. Two channels, one for the visible, one for the near-infrared range, will allow observations in the complete wavelength range from 0.55 to 1.7 mum. To ensure the stability, the instrument is working in vacuum in a thermally controlled environment. The optical design, as well as the opto-mechanical design, of both channels of the instrument and the front-end are described.