Disclosed are apparatus and methods for inspecting or measuring one or more semiconductor targets. An incident beam is directed towards a first target as the first target substantially, continuously moves such that the incident beam remains directed at such first target during a first time period in which the first target substantially, continuously moves between a first position and a second position. An output beam scattered from the first target, in response to the incident beam being directed towards the first target during the first time period in which the first target substantially, continuously moves between the first and second positions, is detected such that information is obtained from the detected output beam during the first time period. The first time period is selected so that the information that is collected from the detected output beam during such first time period can be used to determine a characteristic of the first target.