Designing optical systems for concentrating the flux of thermal neutrons and x-rays is severely constrained by the requirement of grazing incidence, i.e., the exceedingly small angles for total external reflection at mirror surfaces. As a result, the design principles established for non-imaging (i.e. flux concentrators) optics for visible light must be reconsidered. We present new concepts for improving the attainable flux density from neutron sources. In particular, we show how nested axisymmetric mirror systems including up to three reflections can achieve significantly higher concentrations.
In the case of neutrons the refractive index is slightly less than unity for most elements and their isotopes .
Consequently, thermal and cold neutrons can be reflected from smooth surfaces at grazing-incidence angles. Hence, the
optical technologies developed for x-ray astronomy can be applied for neutron focusing. The focusing capabilities of
grazing incidence neutron imaging optics have been successfully demonstrated using nickel mirrors. The mirrors were
fabricated using an electroformed nickel replication process at Marshall Space Flight Center. Results of the neutron
optics experiments and current status of the multilayer coating replication technique development are presented.