An integrally-formed optical imaging system including at least two facing, reflective surfaces defining a single optical axis and formed on a single piece of material.

A small and inexpensive optical scanning apparatus is attained by an optical block 1 disposed between a rotating mirror 2 and a photosensitive body 3 and having specular surfaces formed at part of inner side of surface so that light from the rotating mirror 2 is reflected within the optical block 1 plural times back and forth and reaches the photosensitive body 3 in order to correct the curvature of field, the distortion aberration and the inclination of surface in an optical scanning system. The length of the optical path within the optical block including reflection is set to 60% or more of the whole length of optical path from the rotating mirror 2 to the photosensitive body 3. The surface of the optical block 1 on the side of the photosensitive body is formed into a curved surface to constitute a concave mirror. The rotating mirror and the photosensitive body are arranged in optically conjugate relation in sub-scanning direction by the focal distance.

An optical device includes a light transmitting non-linear optical material having a first face and a second face. The first and second faces oppose each other. The first face has a plurality of first reflecting portions provided thereon, and the second face has a plurality of second reflecting portions provided thereon. Each of the second reflecting portions corresponds to one of the first reflecting portions. Furthermore, the first and second faces are substantially flat except for at least one convex arcuate portion being formed on at least one of the first and second faces. Additionally, at least one of the first and second reflecting portions is obtained by coating a reflective material on the convex arcuate portion.