A detector (110) and a method for optically determining a position of at least one object (112). The detector (110) comprises at least one optical sensor (114) for determining a position of at least one light beam (134) and at least one evaluation device (164) for generating at least one item of information on a transversal position of the object (112) and at least one item of information on a longitudinal position of the object (112). The sensor (114) has at least a first electrode (126) and a second electrode (128). At least one photovoltaic material (130) is embedded in between the first electrode (126) and the second electrode (128). The first electrode (126) or the second electrode (128) is a split electrode (136) having at least three partial electrodes (140, 142, 144, 146). The detector and the method can determine three-dimensional coordinates of an object in a fast and efficient way.