Pulsed operation of a light barrier that can be operated in a normal mode and in a compensation mode includes repeating a cycle of transmitting electromagnetic radiation over a transmission period recording measured radiation values at various measurement times and establishing whether extraneous light is incident on the detector by examining a measured value curve of the recorded measured radiation values. The respectively next cycle in the normal mode being run through when no extraneous light is incident, and in the compensation mode when extraneous light is incident, at least one compensation measure being carried out in the compensation mode in order to compensate the influence of extraneous light.