A beam shaper has a beam shaping element with an optical property that varies spatially over the profile of an incoming light beam in order to generate a first shaped light beam from the incoming light beam. Then, the information received from a source device is prepared for transmission to the destination device. A variable displacement drive pump controlled by a displacement control member provides pressurized fluid to a drive motor. Common-mode level is established by voltages between current and control terminals of the positive-feedback transistors.