Compact pnCCD-Based X-ray Camera with High Spatial and Energy Resolution: A Color X-ray Camera

For many applications there is a requirement for nondestructive analytical investigation of the elemental distribution in a sample. With the improvement of X-ray optics and spectroscopic X-ray imagers, full field X-ray fluorescence (FF-XRF) methods are feasible. A new device for high-resolution X-ray imaging, an energy and spatial resolving X-ray camera, is presented. The basic idea behind this so-called "color X-ray camera" (CXC) is to combine an energy dispersive array detector for X-rays, in this case a pnCCD, with polycapillary optics. Imaging is achieved using multiframe recording of the energy and the point of impact of single photons. The camera was tested using a laboratory 30 mu m microfocus X-ray tube and synchrotron radiation from BESSY 11 at the BAMline facility. These experiments demonstrate the suitability of the camera for X-ray fluorescence analytics. The camera simultaneously records 69 696 spectra with an energy resolution of 152 eV for manganese K(alpha) with a spatial resolution of 50 mu m over an imaging area of 12.7 x 12.7 mm(2). It is sensitive to photons in the energy region between 3 and 40 keV, limited by a 50 mu m beryllium window, and the sensitive thickness of 450 mu m of the chip. Online preview of the sample is possible as the software updates the sums of the counts for certain energy channel ranges during the measurement and displays 2-D false-color maps as well as spectra of selected regions. The complete data cube of 264 x 264 spectra is saved for further qualitative and quantitative processing.