Abstract: An optical scanner for imaging lines in an object plane (10) onto a linear array (18) in a focal plane (16) either continuously or discretely and comprising a set of four mutually perpendicularly oriented plane corner mirrors (28, 30, 32, 34) providing a reflecting path (L.sub.1, L.sub.2, L.sub.3, L.sub.4, L.sub.5) describing a parallelogram and a plane parallel scanning mirror (22) with a front and back reflecting surface (M.sub.o, M.sub.oo) located mid-way between the first and fourth corner mirrors (28, 34) and oriented so that in the mid scan position (45.degree.) it is parallel to the first corner mirror (28) and therefore perpendicular to the fourth corner mirror (34). As the scan mirror (22) rotates, rays (L.sub.o, L.sub.i) incident from a plurality of lines (15, 17) in the object plane (10) are selectively directed through the optical system arriving at a common intersection (P.sub.oo) on the back surface (M.sub.oo) of the scanning mirror where the rays are colinearly directed (L.sub.