Compensation of scale factor nonlinear error introduced by harmonic distortion for open-loop fiber optic gyroscopes

The scale factor (SF) of a gyroscope is the ratio of the detec-tion output rotational rate and the input, and is expected to be a constant. However, for open-loop interferometric fiber optic gyroscopes (IFOGs) with sinusoidal modulation, harmonic amplitudes are inevitably affected by detection defects, such as nonuniform frequency response of the photodetector or unequal gain of amplification circuits. As a result, harmonic distortion leads to SF nonlinearity, which seriously hinders the accuracy of high-precision gyroscopes. In this Letter, the theoretical form of the SF error introduced by harmonic distortion of open-loop gyroscopes is analyzed, and an effective and simple compensation method is pro-posed. Instead of traversing the whole dynamic range, the proposed method simplifies the calibration pretest, where only a section of the dynamic range needs to be tested. Experimental results on an open-loop IFOG prototype show that, with our proposed method, the SF nonlinear error is suppressed to 2.5 ppm within the range -300 to +300 degrees/s, which is 33 times less than that before compensation. (c) 2023 Optica Publishing Group

Automated summary

This letter analyzes the scale factor nonlinearity error introduced by harmonic distortion in open-loop interferometric fiber optic gyroscopes, and proposes an effective and simple compensation method. Experimental results show that with this method, the scale factor nonlinear error is suppressed to 2.5 ppm within the range of -300 to +300 degrees/s, which is 33 times lower than before compensation.