BINARY OPTIC-CORRECTED MULTISTAGE IMAGING SYSTEM

In accordance with the present invention, a BOE-corrected, off-axis image forming apparatus is disclosed. The apparatus has a first stage with a primary reflective element disposed to reflect light incident from an entrance pupil of the apparatus and form a real image at an intermediate image plane, and a second stage located off-axis with respect to the first stage. The second stage is defined by a secondary reflective and/or refractive assembly which re-images light from the intermediate image plane to a final image plane. A binary optical element (BOE), which has higher-order optical characteristics for providing aspheric correction but extremely low optical power, is provided in one of the stages for correcting aberrations introduced by the other optical elements in the apparatus. The BOE contributes no more than about 3% of the optical power provided by the stage which contains the BOE.