PROPERTIES OF CURVED X-RAY DIFFRACTORS WITH STEPPED SURFACES

Problems in the practical fabrication of high-efficiency x-ray diffractors are discussed and a diffractor with a stepped surface is proposed to overcome these problems. The effects of the diffracting materials' rocking curve width and x-ray penetration on the performance of diffractors with simple geometry are evaluated to determine when diffractor geometries involving doubly curved surface and planes are more advantageous than simple geometries. An example calculation of the performance of a stepped diffractor approximating the Wittry geometry (J. Appl. Phys. 68, 387, 1990) is given and experimental results are presented for the performance of a six-step diffractor using mica as the diffracting material and the fifth-order reflection of CuK-alpha radiation produced by a microfocus x-ray source. It is concluded that the stepped diffractor geometry is a viable solution to the problem of fabricating high-efficiency x-ray diffractors.