FIGURING OF MILLIMETER-THICK ELLIPTICAL MIRROR SUBSTRATE USING NUMERICALLY CONTROLLED LOCAL WET ETCHING WITH LOW-PRESSURE POLISHING M.Nagano1, F.Yamaga1, N.Zettsu1, D.Yamazaki2, R.Maruyama2, K.Soyama2 and K.Yamamura1

1.Introduction Recently, various measurements using neutron beam have attracted much attention because of the ability to identify hydrogen atoms and water molecules exactly, sensitivity to magnetism and hard penetrating power. And high-intensity proton accelerator facilities are constructed for neutron research such as J-PARC in Japan, ISIS-TS2 in UK and SNS in USA. However, neutron intensity is very weak compared with that of X-ray in the synchrotron orbital radiations, even in these latest neutron sources. Therefore, high performance optical devices for focusing of neutron beam are required to realize practical measuring. Reflective aspherical supermirror optics would offer advantage for focusing neutron beam with a wide wavelength range since it has no chromatic aberration.