  We propose and design novel axisymmetric focusing mirrors, known as Wolter
optics, for small-angle neutron scattering instruments. Ray-tracing simulations
show that using the mirrors can result in more than an order-of-magnitude
increase in the neutron flux reaching detectors, while decreasing the minimum
wave vector transfer. Such mirrors are made of Ni using a mature technology.
They can be coated with neutron supermirror multilayers, and multiple mirrors
can be nested to improve their flux-collection ability. Thus, these mirrors
offer simple and flexible means of significantly improving existing and future
SANS instruments. In addition, short SANS instruments might become possible,
especially at compact neutron sources, when high-resolution detectors are
combined with Wolter optics.
