crosshair shaped cross section i e which values are delivered from the line sensors or psds the transmitters and receivers can also be mounted on the shaft ends 10 110 such that the light or laser beam 40 50 is emitted essentially axially parallel to the shaft end 10 the torsion or rolling range of interest for the indicated shaft ends is then computed from the difference values of the abscissa values of the measurement results delivered from the line sensors or the corresponding ordinate values and the distance of the line sensors from a center which is common to them this torsion or roll angle can be determined relatively accurately for the indicated dimensioning on the order of magnitude of roughly 5 microrad according to another configuration of the invention by means of a ground glass screen on which the light beam with a crosshair shaped cross section is incident and projecting optics which projects the image of the ground glass screen onto the line sensors indirect imaging of the light beam can be undertaken in this way it is possible to either enlarge the desired measurement range for example to 300 500 mm or optionally to reduce its size for example to 5 10 mm to reduce costs.