Fabrication of X-Ray Optics for a Portable Total Reflection X-Ray Fluorescence Spectrometer Using Electrolytic in Process Dressing Grinding and Magnetorheological Finishing

Problem statement: A portable X-ray elemental analyzer (total reflection X-ray fluorescence spectrometer) has been developed since 2006 and this spectrometer made it possible to perform ultra trace elemental determination. The intensity of scattered X-rays that become background noise in a spectrum is reduced with the improvement in surface accuracy of an X-ray reflector used in the portable spectrometer and therefore using an X-ray reflector with an ultra-precision specular surface can lead to further improvement in detection limits obtained by the portable spectrometer. Approach: In the present paper, a combination of electrolytic in process dressing (ELID) grinding and Magnetorheological Finishing (MRF) is applied to fabricating an X-ray reflector for the portable spectrometer. Magnetorheological finishing is used as final finishing after ELID grinding. Results: A peak to valley value of 107 nm and a root mean square value of 17 nm in a surface cross section with a length of 27 mm are obtained with the use of ELID grinding and MRF. Conclusion: X-ray reflectors having a large specular surface can be fabricated using a combination of ELID grinding and MRF. Using a grinding wheel containing diamond abrasive grains finer than those in the present paper in ELID grinding can lead to further improvement in surface accuracy of an X-ray reflector.