Abstract: A method for positioning a device emitting and receiving optical radiation for measuring wear in the lining of a container involves fixing the coordinate systems of the device and the container to each other by measuring the position of specific fixing points (P1, P2, P3) in the coordinate system (16) of the device (1). The fixing points have a regular shape. The position of each fixing point is measured by deflecting optical radiation in two intersecting directions across the fixing point, by measuring the optical radiation reflected from the fixing point, by determining on the basis of the optical radiation reflected to the measuring device at least two intersections, in both deflection directions, between the fixing point and the optical radiation emitted, and by calculating, on the basis of these at least four intersections, a directing point, to which the optical radiation emitted by the device is directed for determining the coordinates of the fixing point.