Light grid for detecting an object moved in a direction of movement, namely the y-direction, through a surveillance area of the light grid, having - a light emitting unit comprising a plurality of light emitters, - a light receiving unit comprising a plurality of light receivers, each of the light receivers being associated with one of the light emitters and a light receiver providing reception signals dependent on the incident light intensity, - each pair of associated light emitters (14-1 and 14-2, respectively) and light receivers (22-1 and 22-2, respectively) defines therebetween an effective light beam (28-1 and 28-2, respectively) which is defined in that at each distance x from the light emitting unit a partial shading of this effective light beam (28-1, 28-2) causes a measurable intensity change in the associated light receiver (22-1, 22-2) corresponding to the partial shading, and the effective light beams form the surveillance area in x-z plane, - an evaluation unit for evaluating the received signals, characterized - in that switching lines (A, B, C, D) are defined in the evaluation unit, a switching line (A; B; C; D) within an effective light beam indicates the locations x, y between a light-emitter/light-receiver pair at which an object edge lies when the partial shading of the effective light beam (28-1; 28-2) by the object generates a corresponding received signal, - in that two first, different switching lines (A and B) are defined for each light-emitter/light-receiver pair, - in that at least two further, second switching lines (C and D) of another light-emitter/light-receiver pair are defined, - in that at each point x of the switching lines, i.e. at each distance from the light emitting unit, a quotient of a difference between the y values of the first switching lines (A and B) and a difference between the y values of the second switching lines (C and D) has a different value, - in that the evaluation unit is designed such that, when the object is moved through the surveillance area, to determine the four points in time (t1, t2, t3, t4) at which the first and second switching lines (A, B, C, D) are crossed by the object edge, - and the evaluation unit is further designed to determine from these four points in time (t1, t2, t3, t4) the velocity (v) of the object and the distance x of the object from the light emitting unit in the surveillance area. - a light emitting unit comprising a plurality of light emitters, - a light receiving unit comprising a plurality of light receivers, each of the light receivers being associated with one of the light emitters and a light receiver providing reception signals dependent on the incident light intensity, - each pair of associated light emitters (14-1 and 14-2, respectively) and light receivers (22-1 and 22-2, respectively) defines therebetween an effective light beam (28-1 and 28-2, respectively) which is defined in that at each distance x from the light emitting unit a partial shading of this effective light beam (28-1, 28-2) causes a measurable intensity change in the associated light receiver (22-1, 22-2) corresponding to the partial shading, and the effective light beams form the surveillance area in x-z plane, - an evaluation unit for evaluating the received signals, characterized - in that switching lines (A, B, C, D) are defined in the evaluation unit, a switching line (A; B; C; D) within an effective light beam indicates the locations x, y between a light-emitter/light-receiver pair at which an object edge lies when the partial shading of the effective light beam (28-1; 28-2) by the object generates a corresponding received signal, - in that two first, different switching lines (A and B) are defined for each light-emitter/light-receiver pair, - in that at least two further, second switching lines (C and D) of another light-emitter/light-receiver pair are defined, - in that at each point x of the switching lines, i.e. at each distance from the light emitting unit, a quotient of a difference between the y values of the first switching lines (A and B) and a difference between the y values of the second switching lines (C and D) has a different value, - in that the evaluation unit is designed such that, when the object is moved through the surveillance area, to determine the four points in time (t1, t2, t3, t4) at which the first and second switching lines (A, B, C, D) are crossed by the object edge, - and the evaluation unit is further designed to determine from these four points in time (t1, t2, t3, t4) the velocity (v) of the object and the distance x of the object from the light emitting unit in the surveillance area.