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 m. 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.
Highlights
Neutron radiography is a collection of fast-developing imaging techniques that use the penetrating power of thermal and cold neutrons for elucidating the internal structure of materials and devices, from quantum magnets to running internal combustion engines [1,2]
Important applications of this technique include imaging of fuel cells [3], visualization of hydrogen blisters in iron [4], energy-selective imaging [5], visualization of magnetic fields and domains [6,7], nuclear fuel pins [8,9], porous and geological materials [10], etc. The need for both high spatial and temporal resolution is especially acute in operando studies of proton-exchange membrane fuel cells, where membranes that are a few microns thick are imaged through a thick metal casing, or when imaging hydrogen blisters
The Wolter type I microscope consists of a Wolter type I condenser with a paraboloid and hyperboloid (P-H) mirror pair and a Wolter type I objective with a hyperboloid-ellipsoid (H-E) mirror pair
Summary
Neutron radiography is a collection of fast-developing imaging techniques that use the penetrating power of thermal and cold neutrons for elucidating the internal structure of materials and devices, from quantum magnets to running internal combustion engines [1,2]. The attenuation can be due to the sample or by the magnetic analyzer downstream of the sample if a polarized beam is used for magnetic imaging Important applications of this technique include imaging of fuel cells [3], visualization of hydrogen blisters in iron [4], energy-selective (or Bragg-edge) imaging [5], visualization of magnetic fields and domains [6,7], nuclear fuel pins [8,9], porous and geological materials [10], etc. We previously demonstrated axisymmetric neutron imaging mirrors based on similar designs [18,21,22,23] Despite these developments, the optics that are suitable for polychromatic neutron imaging have relatively short focal lengths, and high solid-angle coverage has not yet been implemented, partially due to the complexity of the fabrication of high-precision mirrors and their novelty for neutron applications. Subtle differences between the three types of Wolter systems make the detailed comparison of their performances a difficult task
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
