Abstract: A Cassegrain telescope uses a pivoted corrector plate to reduce back-reflections. A converging lens is added to the optical path inside a housing of the telescope to focus the light within the telescope. The modified Cassegrain design may be used a hybrid radio frequency and free-space optical commercial communications network.

Abstract: A low cost, high reliability system for correcting aberrations in optical signals is disclosed. A foreoptic assembly, such as a telescope, receives an incoming optical signal and directs it to an active optical element, such as a fast steering mirror. The incoming optical signal is diffracted by a diffractive optical element to shape the image that is formed at a wavefront sensor, such as a quad-cell. The wavefront sensor measures a tip-tilt aberration of the incoming optical signal and the active optical element is adjusted to correct the measured aberration. An outgoing optical signal can be transmitted along substantially the same optical path as the incoming optical signal, but in the opposite direction. Thus, the aberration measured from the incoming optical signal can be automatically accounted for in the outgoing optical signal.