A novel axicon-structured lens

Abstract

A design method based on the theory of structured lenses gives a new type of axicon with long focal depth.

Simulation of X-ray diffraction profiles for bent anisotropic crystals

“…This requires a correct treatment of the crystal anisotropy. The unified formulation presented here extends the cases treated in literature for isotropic Bragg crystals like (Caciuffo et al, 1990;Erola et al, 1990) and for anisotropic Laue crystals (Shi, 2011) to the general case of two-moment bending Laue or Bragg anisotropic crystals.…”

“…In this section we analyze a Si111 crystal 0.07 cm thick used to focus a 50 keV X-ray beam in sagittal direction (Shi, 2011). The diffraction plane in the meridional direction is affected by the anticlastic curvature originated by the sagittal radius, which is much smaller that the typical radii used in meridional focusing.…”

“…Note that the Poisson's ratio and the anticlastic radius in a crystal cut along directions different from the crystallographic axes are different. Table 1 Compliance tensor s elements (×10 −12 m 2 /N) for most used cubic perfect crystals (Si, Ge: (Wortman & Evans, 1965), Diamond: (Berman, 1965); see review in (Hedayat et al, 2012) Equivalence for the compliance tensor indices for different reference frames used in literature:Shi (Shi, 2011), Honkimäki (Honkimäki, 2014, Schulze (Schulze, 1994) (Schulze & Chapman, 1995), and Zhang (Zhang et al, 2014 …”

“…This model has been successfully applied for calculating the diffraction profiles of high energy monochromators used in beamlines at many synchrotrons (APS, NSLS, ESRF, Spring-8, Petra, Diamond, etc.). Again, we present here a formulation that can be applied for crystals bent in two directions (meridional and sagittaly, thus unifying previous uses of the Penning-Polder theory for meridionally bent crystals, isotropic (Sanchez del Rio et al, 1997) or anisotropic (Schulze & Chapman, 1995), or for sagittal bending (Shi, 2011). Approximation level (d), thus solving TakagiTaupin equations will be addressed in a future work.…”