Noise Analysis of a Passive Resonant Laser Gyroscope.

Kui Liu,Karl Ulrich Schreiber,Ke Li,Zehuang Lu,Zongyang Li,Xiaohua Feng,Yuanbo Du,Fenglei Zhang,Jie Zhang

doi:10.3390/s20185369

Abstract

Large-scale laser gyroscopes have found important applications in Earth sciences due to their self-sufficient property of measurement of the Earth’s rotation without any external references. In order to extend the relative rotation measurement accuracy to a better level so that it can be used for the determination of the Earth orientation parameters (EOP), we investigate the limitations in a passive resonant laser gyroscope (PRG) developed at Huazhong University of Science and Technology (HUST) to pave the way for future development. We identify the noise sources from the derived noise transfer function of the PRG. In the frequency range below , the contribution of free-spectral-range (FSR) variation is the dominant limitation, which comes from the drift of the ring cavity length. In the to frequency range, the limitation is due to the noises of the frequency discrimination system, which mainly comes from the residual amplitude modulation (RAM) in the frequency range below 2 Hz. In addition, the noise contributed by the Mach–Zehnder-type beam combiner is also noticeable in the 0.01 to 2 Hz frequency range. Finally, possible schemes for future improvement are also discussed.

Highlights

Optical interferometers have important applications in the field of precision measurement.Large-scale interferometers have much better sensitivity and resolution; many ground-breaking works benefiting from their high sensitivities have been reported
The establishment of the absolute scale factor and all systematic errors are essential for the measurement of the Earth orientation parameters (EOP), Lense–Thirring frame dragging detection, and the search for the Lorentz violation by such high-resolution gyroscopes [37]
We found that in different frequency ranges, the most prominent noise sources of the gyroscope are different

Summary

Introduction

Optical interferometers have important applications in the field of precision measurement.Large-scale interferometers have much better sensitivity and resolution; many ground-breaking works benefiting from their high sensitivities have been reported. Optical interferometers have important applications in the field of precision measurement. Large-scale Sagnac interferometers play a vital role in measuring the rotation of the Earth [4]. Instruments based on the Sagnac effect have many applications in different fields [4,5,6,7,8,9,10,11,12,13,14,15,16]. Optical gyroscopes utilize the non-reciprocal phenomenon inside a ring cavity introduced by the rotation of the cavity frame based on the Sagnac effect, which means two beams would experience an unequal round-trip travel time in opposite directions inside an identical light path of a rotating ring interferometer. The interferometric gyroscopes convert the travel time difference into the accumulated phase difference of the opposite beams, while the resonant gyroscopes measure the Sensors 2020, 20, 5369; doi:10.3390/s20185369 www.mdpi.com/journal/sensors

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