Characterization of a large-area full-field X-ray fluorescence imaging system based on a commercial full-frame CMOS camera

Abstract

A new large-area and low-cost full-field X-ray fluorescence imaging system was developed for simultaneous mapping of several chemical elements. It consists of a commercially available full-frame visible-light CMOS digital camera coupled to a tungsten pinhole-collimator. The X-ray fluorescence is produced by irradiating the sample with an external X-ray tube. The system magnification can be continuously adjusted from 0.55 to 1.43 by changing the position of the pinhole in the collimator. To allow X-ray sensitivity, the glass window of the CMOS sensor was removed and the front glass cover of the camera was replaced by an X-ray window. The x-ray spectra and 2D X-ray fluorescence images of different elements are obtained by processing a series of images acquired in a spectroscopy mode using the CMOS camera. The camera is able to resolve fluorescence lines up to 22 keV, with an energy resolution of 213 eV at 6.4 keV. The experimental spatial resolution is 105 μm when using a 90 μm pinhole at 1.43× magnification. The capabilities of the system in performing the 2D resolved X-ray fluorescence imaging were investigated by testing samples of different materials and geometries. The obtained X-ray fluorescence spectra and images show that the system is able to accurately identify the presence of several different elements and visualize their spatial distributions.