Design of Neutron Microscopes Equipped with Wolter Mirror Condenser and Objective Optics for High-Fidelity Imaging and Beam Transport

Abstract

We present and compare the designs of three types of neutron microscopes for high-resolution neutron imaging. Like optical microscopes, and unlike standard neutron imaging instruments, these microscopes have both condenser and image-forming objective optics. The optics are glancing-incidence axisymmetric mirrors and therefore suitable for polychromatic neutron beams. The mirrors are designed to provide a magnification of 10 to achieve a spatial resolution of better than 10 μm. The resolution of the microscopes is determined by the mirrors rather than by the L/Dratio as in conventional pinhole imaging, leading to possible dramatic improvements in the signal rate. We predict the increase in the signal rate by at least two orders of magnitude for very high-resolution imaging, which is always flux limited. Furthermore, in contrast to pinhole imaging, in the microscope, the samples are placed far from the detector to allow for a bulky sample environment without sacrificing spatial resolution.

Neutron instrument concepts for a high intensity moderator at the European spallation source

“…While such installations have not been considered in these preliminary simulation models, back-of-the-envelop calculations show that the instrument would support a number of applications in this www.nature.com/scientificreports/ regime from crystalline phase mapping to dark-field contrast imaging, probing apart from macroscopic structures also microscopic structures through small-angle scattering analysis [47][48][49][50][51] . Furthermore, when considering to realize a long instrument cave, also the use of NMO, such as Wolter optics should be considered to leverage corresponding flux gains at high resolution for small samples as would be enabled by a microscopy-type setup with a condenser and objective lens 12 .…”

“…More specifically, SANS can profit from a larger high-intensity moderator providing a cold spectrum when considering larger samples, requiring a longer instrument, which in turn can also be used for higher resolution measurements. Alternatively, novel nested mirror optics (NMO) concepts such as Wolter optics [9][10][11][12] have been considered in order to harvest neutrons from the large moderator face and focus them on the detector in a relatively short instrument. Spin-echo is considered to profit from a similar strategy when focusing on the sample position, while e.g.…”