APPARATUS

摘要

According to an aspect of the invention, there is provided a detector module for defining at least a part of a wall of a vacuum chamber of a charged particle beam assessment tool, the delector module comprising: a detector configured to operate in the vacuum chamber, the detector being configured to be alignable with an incidental charged particle beam path; and a support for defining at least a part of the wall of the vacuum chamber, the support comprising a feedthrough to which the detector is mounted, wherein the detector is electrically connected through the feedthrough . wherein applied disturbances deform the support; wherein the detector module is configured so that, with disturbances to the detector and/or support, the position of the detector during operation of the detector is maintained relative to the incidental charged particle beam path.