Beam steering optical arrangement using risley prisms with surface contours for aberration correction

Abstract

A steerable optical arrangement. The inventive arrangement includes a first prism mounted for rotation about an optical axis and a second prism mounted for rotation about the optical axis. In accordance with the inventive teachings, the first prism and/or the second prism have at least one surface contoured to correct for optical aberration. In the illustrative embodiment, the first and second prisms are Risley prisms. In addition, the illustrative implementation includes a first motor arrangement for rotating the first prism about the optical axis and a second motor arrangement for rotating the second prism about the optical axis. A controller is provided for activating the first and second motors to steer the beam at an angle &phgr; and nod the beam at an angle &thgr;. At least two surfaces at least one prism is contoured to correct for astigmatism, coma, trefoil and other non-rotationally symmetric aberration. The contour is effected by laser etching, micro-machining or optical thin-film coating of the prisms in the manner disclosed herein.