Magnetic Optical Bearing (MOB) Design for Mirror Wavelength Scans in a Spaceborne Interferometer

NASA maintains the Geosynchronous Operational Environmental Satellite (GOES) fleet for severe weather observation and anomalous atmospheric behavior, such as the greenhouse effect. A critical instrument flown on these satellites is the Fourier Transform Infrared (FTIR) interferometer used for atmospheric element detection. Traditionally, the scanning element of this device has relied on mechanical designs such as flexures to yield long term, reliable, and accurate scanning motion and control. Although flight tested, flexure designs are subject to wear, singlepoint failures, and do not usually allow corrective active control in degrees-of-freedom other than in the primary axis of motion. Magnetic bearings designed for spaceborne interferometry can compensate for these deficiencies. However, previous designs been large, heavy and inefficient. This paper discusses a novel magnetic bearing configuration which alleviates these problems by using magnetic hybrid actuators. Here, three identical two degree-of-freedom magnetic hybrid actuators comprise a six degree-of-freedom actively controlled scanning magnetic opticaL bearing. The design of this overall system is developed in the paper. Furthermore, a prototype of one of the three identical actuators is designed, built and tested with the results discussed. Although presented in the context of optical devices, this magnetic bearing may also be possibly used in such devices as coordinate measuring machines, linear axis control, lithographic steppers, and other precision control devices.