In conventional triangulation systems for 3-D sensing there is a trade-off between range of depth and resolution. We propose a triangulation system with a large depth of field (1 m or more) and, at the same time, high resolution (20µm or better). The system is based essentially on a tele-axicon in the illumination device and on the use of the Scheimpflug condition in the observation device. A suitable scanning-by-deflection geometry is described.