The present disclosure relates to an improved optical arrangement for an optical imaging system or the like, comprising: an optical device; a digital micromirror device having a plurality of individually addressable micromirrors; a convex mirror; and a concave mirror concentric to the convex mirror. The convex mirror and the concave mirror define an optical triplet which is located in an optical path with the digital micromirror device and the optical device. The concave mirror comprises two concave mirror sections, one or both concave mirror sections being moveable relative to the convex mirror so as to control an image mapping between the digital micromirror device and the optical device.