Closed-Loop Alignment of X-ray Spectrometers

Abstract

Traditionally, spectrometers are manually aligned to the optical axis of the X-ray source using visual aids such as lasers or by manual mechanical means, with the goal of being able to characterize the emission spectra of the source by taking spectral measurements. However, manual adjustment is time-consuming and tedious, especially when thick collimators with small apertures are used, which considerably increases the effects of human error. This leads to inaccurate characterization of emission spectra and might be a cumbersome process to do repeatedly and systematically, if the X-ray origin is shifted at any point of time later. Precise and accurate alignment is expected by manufacturers of industrial X-ray sources, and measurement of the source emission spectrum is an important part of characterizing the source's performance, which is made possible by aligning the spectrometer to the optical axis of the X-ray source. This thesis project focuses on developing an automated setup using motorized stages to position the spectrometer and a closed-loop Nelder-Mead optimization mechanism to perform the alignment and demonstrate the results compared to manual alignment. The obtained results are compared with theoretical Monte-Carlo simulations of the X-ray source flux to observe similarities.