Disturbance Effects On A Ground Based Precision Tracking System

A major concern when considering the design of a ground based precision tracking system, is the optical jitter that will result from various environmental disturbances. This paper considers disturbances including wind, angular seismic, linear seismic, gyroscope noise, electronics noise, and atmospheric turbulence. The disturbances may couple into a tracking system by applying forces or torques directly on the optical components, or by transmitting through the control loops which in turn place jitter into the optical path. The tracking system design can be altered by using different control system configurations to reject the expected disturbances. For instance, if seismic disturbances are large and expected to cause jitter in the optical train it may be desirable to add an autoalignment system to maintain dynamic optical train alignment. A further level of complexity is the selection of a reference for the autoalignment system. It might be a gyroscope stabilized mirror or simply a softly suspended mirror. This paper reports a trade study between the various disturbances and the various hardware configurations that result in some general guidelines when selecting the components in the design of a precision tracking system.