POSITION SENSOR AND LITHOGRAPHIC APPARATUS

摘要

A position sensor is configured to measure a position data of a target. The position sensor includes a radiation source configured to irradiate a radiation beam, a first grating configured to diffract the radiation beam in a first diffraction direction into at least a first order diffraction beam, and a second grating, arranged in an optical path of the first order diffraction beam, the second grating being configured to diffract the first order diffraction beam diffracted at the first grating in a second diffraction direction substantially perpendicular to the first diffraction direction. The second grating is connected to the target. A first detector is configured to detect at least a part of the beam diffracted by the first grating, and at least one second detector is configured to detect at least part of the beam diffracted by the first grating and the second grating.