To provide an elliptic polarimeter, a measuring device and a method, a lithography device and a method.
The elliptic polarimeter has an optical component and a detector. The optical component has two double-refractive parts which carry out optical communication via a boundary surface. The light incident on the boundary surface is divided into two reflecting components and two transmitted components. The detector is performed so as to measure the characteristics of at least three components in these four components. The polarizing state of the incident light can be determined, based on the measured characteristics.