Balanced Filters for an Annular Counter

Abstract

Annular counters are finding increasing application in x-ray diffraction. They are well suited for detection of weak diffracted beams because of their ability to capture an entire Debye ring. This is especially true in the case of microfocus diffractometers, where the Illuminated sample area may be a spot less than 100 microns in diameter. Unfortunately, the geometry of the annular counter precludes the use of a diffracted beam, monochromator. However, near monochromatic conditions can be achieved by using balanced filters to bracket the K alpha line, or any other line of interest. We discuss here the application of balanced filters to the Rigaku microdiffractometer, which uses Debye-Scherrer optics.