Use of an arrangement for characterizing mode propagation time differences in an optical multimode fibre to be characterized, the arrangement comprising: a laser for generating a coherent input light beam, a light modulator for modulating the input light beam into a modulated light beam, wherein the light modulator is a spatially resolved light modulator, by means of which the electrical field strength (E x,y) and/or the phase of the input light beam of individual cross-sectional regions (x,y) can be modified, in particular reduced, a graphics card for controlling the light modulator, a multimode fibre to be investigated, into which the modulated light beam is injected, and a light sensor for capturing an output light beam emerging from the multimode fibre, wherein the use comprises the following method steps: • generating the coherent input light beam, comprising in particular collimated light, by means of the laser, • exposure of the spatially resolved light modulator with the input light beam in reflection at an angle with respect to the perpendicular to the plane of reflection of the light modulator, as a result of which a spatially modulated light beam is generated, which is reflected out of the input light beam and follows a different path to that from which it has come, • guiding the spatially modulated light beam by means of the multimode fibre to be investigated, wherein an output light beam exits the multimode fibre to be investigated, • capturing the output light beam by the sensor and • evaluation of the output light beam, • wherein by means of the spatially resolved light modulator one mode of the fibre is selectively excited and its propagation time measured. a laser for generating a coherent input light beam, a light modulator for modulating the input light beam into a modulated light beam, wherein the light modulator is a spatially resolved light modulator, by means of which the electrical field strength (E x,y) and/or the phase of the input light beam of individual cross-sectional regions (x,y) can be modified, in particular reduced, a graphics card for controlling the light modulator, a multimode fibre to be investigated, into which the modulated light beam is injected, and a light sensor for capturing an output light beam emerging from the multimode fibre, wherein the use comprises the following method steps: • generating the coherent input light beam, comprising in particular collimated light, by means of the laser, • exposure of the spatially resolved light modulator with the input light beam in reflection at an angle with respect to the perpendicular to the plane of reflection of the light modulator, as a result of which a spatially modulated light beam is generated, which is reflected out of the input light beam and follows a different path to that from which it has come, • guiding the spatially modulated light beam by means of the multimode fibre to be investigated, wherein an output light beam exits the multimode fibre to be investigated, • capturing the output light beam by the sensor and • evaluation of the output light beam, • wherein by means of the spatially resolved light modulator one mode of the fibre is selectively excited and its propagation time measured. • generating the coherent input light beam, comprising in particular collimated light, by means of the laser, • exposure of the spatially resolved light modulator with the input light beam in reflection at an angle with respect to the perpendicular to the plane of reflection of the light modulator, as a result of which a spatially modulated light beam is generated, which is reflected out of the input light beam and follows a different path to that from which it has come, • guiding the spatially modulated light beam by means of the multimode fibre to be investigated, wherein an output light beam exits the multimode fibre to be investigated, • capturing the output light beam by the sensor and • evaluation of the output light beam, • wherein by means of the spatially resolved light modulator one mode of the fibre is selectively excited and its propagation time measured.