Abstract
The thermal performance under variable temperature conditions of fiber coils with double-cylinder (D-CYL) and quadrupolar (QAD) winding methods is comparatively analyzed. Simulation by the finite element method (FEM) is done to calculate the temperature distribution and the thermal-induced phase shift errors in the fiber coils. Simulation results reveal that D-CYL fiber coil itself has fragile performance when it experiences an axially asymmetrical temperature gradient. However, the axial fragility performance could be improved when the D-CYL coil meshes with a heat-off spool. Through further simulations we find that once the D-CYL coil is provided with an axially symmetrical temperature environment, the thermal performance of fiber coils with the D-CYL winding method is better than that with the QAD winding method under the same variable temperature conditions. This valuable discovery is verified by two experiments. The D-CYL winding method is thus promising to overcome the temperature fragility of interferometric fiber optic gyroscopes (IFOGs).
Highlights
The interferometric fiber optic gyroscope (IFOG) is an inertial instrument extensively used in navigation, orientation, and stabilization systems in recent years [1]
It is well know that the stability performance of an IFOG is greatly worsened under the influence of time-varying temperature gradients, especially asymmetric temperature excitation, the key problem in developing highly-accurate IFOGs is the compensation of thermally induced drifts errors [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21]
Considering the characteristics of IFOGs, we concluded that thermally induced drift errors are mainly caused by the following five factors: unstable wavelength of the light source, the temperature drift of integrated optical devices (Y waveguide) [2], unstable performance of electronics, unstable performance of PN dark current and thermal noise of the photoelectric detector, and thermally induced changes of the refractive index of the fiber coil
Summary
The interferometric fiber optic gyroscope (IFOG) is an inertial instrument extensively used in navigation, orientation, and stabilization systems in recent years [1]. The principal configuration of IFOG consists of six parts: light source, optical coupler, Y-branch, electro-optical phase modulator, photoelectric detector and fiber coil. Considering the characteristics of IFOGs, we concluded that thermally induced drift errors are mainly caused by the following five factors: unstable wavelength of the light source, the temperature drift of integrated optical devices (Y waveguide) [2], unstable performance of electronics, unstable performance of PN dark current and thermal noise of the photoelectric detector, and thermally induced changes of the refractive index of the fiber coil. In order to overcome the thermally induced drift errors, some measures can be adopted to suppress the inducing factors. To exclude the influence of the light source wavelength on spectral characteristics under temperature variation conditions, an erbium-doped superfluorescent fiber source (SFS) is adopted [3].
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