PLTP in situ measurement method of Wolter-I type mandrel

Abstract

Wolter-I type grazing incidence focusing mirrors are widely used for imaging applications in the field of x-ray astronomy. In an electroforming replication process, the accuracy of a mirror is directly determined by the mandrel. A portable long trace profiler (PLTP) is developed and implemented to measure the generatrix error of the Wolter-I type mandrels on an ultra-precision machine tool. The measurement accuracy is confirmed via optical flat measurement experiment. Two PLTP in situ measurement methods, pentaprism scanning and direct scanning, are studied. The comparison of the methods and the corresponding measurement errors are analyzed and discussed. The necessity of PLTP measurement in evaluating optical performance is illustrated through three-dimensional ray tracing.