An optically interrogated microgyroscope using an out-of-plane lamellar grating

This paper describes the design and principle behind the demonstrated novel lamellar grating out-of-plane gyroscope design. The sensing mechanism is based on out-of-plane motion of movable light-reflecting beams changing the phase relationship between the light reflected off the two sets of beams. This phase relationship is manifested as an intensity change in the zeroth-order diffracted light. The device consists of two in-plane 180° out-of-phase vibrating masses with a set of overlapping light-reflecting beams behaving essentially as a lamellar grating. The commercial SOI-MUMPS process was used to fabricate a prototype. The gyroscope demonstrated a sensitivity of 17.8 μV/(°/s) and linearity error of less than 0.6%. Design issues were addressed and show promise to be overcome. Post-fabrication tuning and better optics design can improve the performance greatly with respect to the current prototype setup.