MEMS based ring laser gyroscope with reduced lock-in

摘要

A ring laser gyroscope (RLG) includes moveable mirrors and a Micro-Electro-Mechanical Systems (MEMS) actuator coupled to the moveable mirrors to cause a respective displacement thereof that induces a phase modulation on counter-propagating light beams relative to one another. The induced phase modulation creates an optical path difference between the counter-propagating light beams corresponding to a virtual rotation that reduces the lock-in of the RLG.

主权项

1. A ring laser gyroscope, comprising:
an active gain medium for generating first and second light beams; a closed optical path through which the first and second light beams counter-propagate; first and second moveable mirrors within the closed optical path; a Micro-Electro-Mechanical Systems (MEMS) actuator coupled to the first and second moveable mirrors to cause a respective displacement thereof that induces an induced phase modulation on the first and second light beams relative to one another, thereby creating a modulated optical path length difference between the first and second light beams corresponding to a virtual rotation to reduce the lock-in, wherein the MEMS actuator is configured to continuously displace the first and second mirrors with a pre-defined motion profile and with arbitrary phase shift therebetween to produce the induced phase modulation; wherein the first and second moveable mirrors are corner cube mirrors, wherein each of the corner cube mirrors includes two flat mirrors placed at right angles to each other, wherein displacement of the corner cube mirrors by the MEMS actuator changes an optical path length experienced by the first and second light beams without changing the closed optical path through which the first and second light beams propagate; wherein the first and second corner cube mirrors are mechanically coupled together and actuated by a single MEMS actuator to achieve fully synchronized out-of-phase motion with equal mirror displacement; a semiconductor substrate including the first and second moveable mirrors and the MEMS actuator therein; a detector coupled to the closed optical path to detect a beat pattern caused by the first and second light beams counter-propagating through the closed optical path; and a processor coupled to the detector to receive the beat pattern and configured to determine the induced phase modulation based on the pre-defined motion profile, the processor further configured to determine an angular rotation rate of the ring laser gyroscope by eliminating the induced phase modulation from the beat pattern.