|
KMID : 1151820180120010017
|
|
Journal of the Korean Society of Radiology
2018 Volume.12 No. 1 p.17 ~ p.22
|
|
|
Calculation of Reflectivity for W/Si Multilayer Mirror of Small d-Spacing
|
|
Chon Kwon-Su
|
|
|
Abstract
|
|
|
|
Multilayer mirrors are optical elements that can replace single crystal optical elements such as silicon or germanium, and they have artificial diffraction plane of a thickness of several nanometers. We examined the first Bragg angle and the reduction of reflectivity by variation of layer thickness in a W/Si multilayer mirror of small d-spacing. A W/Si multilayer mirror for an incidence angle of 0.55° and an energy of 17.5 keV was designed and showed a maximum reflectivity of 72.67%. When the thickness of tungsten or silicon layer was simultaneously changed, the first Bragg angle was shifted and the reflectivity was reduced. When there was a change in thickness for one layer of W/Si multilayer, no change in the reflectivity was showed but the unevenness of the envelope was observed. Reduction of reflectivity was also observed at random Gaussian thickness variations. It is possible to predict the tolerance of multilayer mirror by examining the reflectivity degradation according to the thickness change in the W/Si multilayer mirror of small d-spacing.
|
|
|
KEYWORD
|
|
|
X-ray Optics, Multilayer Mirror, d-Spacing, Reflectivity
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|