Figuring of plano-elliptical neutron focusing mirror by local wet etching

Local wet etching technique was proposed to fabricate high-performance aspherical mirrors. In this process, only the limited area facing to the small nozzle is removed by etching on objective surface. The desired objective shape is deterministically fabricated by performing the numerically controlled scanning of the nozzle head. Using the technique, a plano-elliptical mirror to focus the neutron beam was successfully fabricated with the figure accuracy of less than 0.5μm and the focusing gain of 6. The strong and thin focused neutron beam is expected to be a useful tool for the analyses of various material properties.