Patent ID: 8876294

Claim:
An image forming apparatus comprising: an optical scanning device including a light source element configured to radiate a light beam, an optical deflector configured to deflect the light beam two-dimensionally, a concave mirror configured to deflect the light beam deflected by the optical deflector, and a target scanning surface that is transparent and having a two-dimensional image formed thereon by the light beam deflected from the optical deflector via the concave mirror; and a projection optical system including a convex mirror and configured to enlarge and project the two-dimensional image on a target projection surface; wherein the target projection surface includes a reflection surface of a half mirror, wherein the half mirror is positioned outside of the image forming apparatus and configured to transmit a part of a light incident on the half mirror and reflect another part of the light incident on the half mirror, wherein the optical deflector and the concave mirror are arranged, so that a sign of a deflection angle of the optical deflector and a sign of a deflection angle of the concave mirror become opposite to each other.