Objective mirror assembly for a reflecting microscope comprising large aspheric aluminised speculum metal primary mirror made by I. H. Ford on C. R. Burch's mirror figuring machine at Bristol (Inv. No. 1986-113), plus a small aluminised spherical mirror, made from part of a ball bearing, in a kinematically designed mount allowing backlash-free adjustment of the primary mirror in the x and y directions and the secondary mirror in the z direction, made between about 1954 and 1964. Also an engineering drawing of the assembly.