We propose a new design of a multi-axis atom interferometer (AI) gyroscope based on a grating chip, which allows a single input laser beam for atomic trapping and coherent manipulation. Multiple AIs are formed by the input laser beam along with the other four diffractive beams generated by the grating chip. The rotation induced phase shifts from different input axes lead to different spatial interference fringes due to the modulation of the atomic velocity. With the point source interferometry (PSI) and the spatially resolved detection, multi-axis rotations may be measured by imaging the final atomic cloud after the interferometer sequence and decoding the information of spatial fringes from different input axes. Monte-Carlo based simulation are used for evaluating the proposed scheme and its application as a multi-axis gyroscope.
Point-source interferometry (PSI) is a promising technique that enables the realization of compact and multi-axis cold-atom inertial sensors. However, scale-factor errors in the rotational signal, due to the shape and size of the initial atomic distribution, constitute a major drawback. In this paper, we present a method for calibrating the rotational scale-factor. This method relies on the application of a known bias rotation and a compensation scheme that decouples the PSI sensor from the vehicle’s rotational dynamics. We employ a Kalman filter protocol to track the scale-factor error, paving the way for real-time implementation of the calibration method. Through simulations, we demonstrate the effectiveness of the method and the stabilization of the PSI sensor scale-factor.
Using the technique of point source atom interferometry, we characterize the sensitivity of a multi-axis gyroscope based on free-space Raman interrogation of a single source of cold atoms in a glass vacuum cell. The instrument simultaneously measures the acceleration in the direction of the Raman laser beams and the component of the rotation vector in the plane perpendicular to that direction. We characterize the sensitivities for the magnitude and direction of the rotation vector measurement, which are 0.033
∘/s and 0.27
∘ with one second averaging time, respectively. The sensitivity could be improved by increasing the Raman interrogation time, allowing the cold-atom cloud to expand further, correcting the fluctuations in the initial cloud shape, and reducing sources of technical noise. The unique ability of the PSI technique to measure the rotation vector in a plane may permit applications of atom interferometry such as tracking the precession of a rotation vector and gyrocompassing.