DOME-DISC: Diffractive optics metrology enabled dithering inertial sensor calibration

We demonstrate 107-ppm accurate scale-factor and bias calibration of a commercial Coriolis force gyroscope, in which the typical un-calibrated scale factor variations are ~100,000-ppm. In this paper, we present a proof-of-concept result on calibration architecture - Diffractive Optics Metrology Enabled Dithering Inertial Sensor Calibration (DOME-DISC). DOME-DISC consists of a piezoelectric dither stage to provide built-in mechanical stimulus to the gyroscope attached to it. The motion of the dithering stage is measured by imaging an optical diffraction pattern created by an incident laser off diffraction gratings on the dither stage. In order to calibrate the gyroscope, the stage motion needs to be measured accurately and precisely. The motion of the stage is measured using the Nano Optical Ruler Imaging System (NORIS), with absolute accuracy of ~30nm over several millimeters, stable over several hours. NORIS provides parts-per-million stage motion measurement accuracy. In this paper, an angular dither motion of 0.1 to 0.5 degrees was optically measured with ~ 0.1 millidegree resolution. By measuring the scale factor and bias for a gyroscope on the dither stage mounted directly on a commercial rate table, and matching the gyroscope input-output curve to 100ppm, we demonstrate the capability to measure in-package gyroscope characteristics within the error limits of the commercial rate table.