Design considerations for optical pointing and scanning mechanisms

Optical pointing and scanning mechanisms require inter-related optical, mechanical and electrical engineering and manufacturing disciplines. Such devices are employed in extremely diversified fields of photographic imaging, forward looking infrared (FLIR) systems, laser projection displays (LPD), target acquisition, aerial reconnaissance, remote sensing, and free space laser telecom. The degrees of freedom commonly applied include rotary scanning, raster and vector scanning, and limited angle gimbals. Support systems include flexures, ball bearings, and gas bearings. The performance of the optical payload supported by the pointing or scanning mechanism is paramount and dominates the process of materials selection, structural analysis, actuator selection, and control system development. This paper introduces the tradeoffs among range and type of motion, actuator types, angular sensor types, bearing types, and control systems applied to these types of systems. Actual product design and performance data is presented for a high-speed rotary scanner, a fast "nodding" scanner for a FLIR a flexure supported fast steering mirror (FSM), and several ball bearing and a gas bearing gimbal designs.