The AFIT MEMS Interferometric Gyroscope

With the invention of Micro Electro-Mechanical Systems (MEMS) it has become possible to fabricate micro-inertial sensors. These new sensors have application in creating autonomous guided weapons systems. New technologies like Micro Unmanned Aerial Vehicles (UAVs), which cannot use conventional inertial sensors, rely on technologies like micro-inertial sensors to operate. Also, such sensors have the capability to reduce both power and space consumption on conventional aircraft. This technology is not yet mature, and current micro-inertial sensors do not have the accuracy required for highly precise navigation. To try to increase the accuracy of micro-inertial sensors, researchers are turning toward micro-optical gyroscopes. Creating a working micro-optical gyroscope is a difficult proposition as their small size precludes micro-optical gyroscopes from having large enough path lengths to sense useful rotation rates. Techniques need to be developed to create micro-optical gyroscopes with path lengths long enough to sense navigation grade rotation rates. This research proposes a new type of MEMS optical gyroscope. The device, called the AFIT MiG is an open loop Sagnac interferometer on a MEMS die. Mirrors are placed on the die to spiral light inward from the outside to the center of the die thereby increasing the optical pathlength of the device. When the AFIT MiG was simulated using flight profiles generated in MATLAB, the optical path length of the device was long enough to measure rotation rates, which were greater in strength than the noise inherent in the measurement.