coudé focus kânun-e ârenjvâr, ~ kudé Fr.: foyer coudé An → optical system in which the → beam of light from the → primary mirror is reflected down through the instrument's → polar axis by a path bent like an → elbow. Since the focus remains fixed with respect to the Earth, light can be analyzed with permanently installed instruments. In addition long → focal lengths allow higher → spectral dispersions. From Fr. coudé "elbowed," from coude "elbow," L. cubitus; → focus. |