A detector (110) for determining a position of at least one object (118) is disclosed. The detector (110) comprises: at least one optical sensor (112), the optical sensor (112) being adapted to detect a light beam (150) traveling from the object (118) towards the detector (110), the optical sensor (112) having at least one matrix (152) of pixels (154); and at least one evaluation device (126), the evaluation device (126) being adapted for determining an intensity distribution of pixels (154) of the optical sensor (112) which are illuminated by the light beam (150), the evaluation device (126) further being adapted for determining at least one longitudinal coordinate of the object (118) by using the intensity distribution.