Method for inspection of a target object, control system and inspection system

A method for inspection of a target object (38), the method comprising irradiating a reference surface (66) having a non-flat reference profile (68) with radiation (58); determining reference response data based on detected radiation (58) having interacted with the reference surface (66); irradiating a target object (38) with radiation (58), the target object (38) comprising a target surface (70) having a non-flat target profile (72) corresponding to the reference profile (68); determining inspection response data based on detected radiation (58) having interacted with the target object (38); and determining at least one parameter of the target object (38) based on the reference response data and the inspection response data. An alternative method; a control system (18) for controlling an emitter system (40) and a detector system (42); and an inspection system (14) comprising a control system (18), an emitter system (40) and a detector system (42), are also provided.