Cartesian blind spot correction using two non-equal Risley elements.

Traditional Risley prism applications employ two identical prisms to create a pointing/steering function through axial rotation of the prisms. In system assembly, finite separation of the elements results in an inaccessible blind spot in the system output. Past blind spot corrections introduced a third element, increasing system complexity, size, weight, and power and complicating output angular resolution. An alternative method is presented, using two non-equal Risleys to overcome the blind spot in Cartesian space, at the cost of creating a blind spot in angular space. For a subset of Risley prism applications, the presented approach offers significant utility.