Calibration of a compact XUV soft X-ray monochromator with a digital autocollimator in situ

摘要

A digital autocollimator of resolution 0.1 mu rad (0.02 arcsec) serves as a handy correction tool for calibrating the angular uncertainty during angular and lateral movements of gratings inside a monochromator chamber under ultra-high vacuum. The photon energy dispersed from the extreme ultraviolet (XUV) to the soft X-ray region of the synchrotron beamline at the Taiwan Light Source was monitored using molecular ionization spectra at high resolution as energy references that correlate with the fine angular steps during grating rotation. The angular resolution of the scanning mechanism was <0.3 mu rad, which results in an energy shift of 80 meVat 867 eV. The angular uncertainties caused by the lateral movement during a grating exchange were decreased from 2.2 mu rad to 0.1 mu rad after correction. The proposed method provides a simple solution for on-site beamline diagnostics of highly precise multi-axis optical manipulating instruments at synchrotron facilities and in-house laboratories.