Optically compensated dual-polarization interferometric fiber-optic gyroscope

Abstract

We first introduce optical compensation into the field of interferometric fiber-optic gyroscopes (IFOGs), using the opposite polarity of the disturbance between two orthogonal polarization states to suppress polarization-fluctuation-induced noise. A dual-polarized IFOG, in which the fast and slow axes of polarization-maintaining fiber work simultaneously, is implemented and tested. Interference signals of the two axes are added to achieve optical compensation. Experiments show that the IFOG's sensitivity is effectively enhanced in compensated output: all Allan variance indices are improved, among which bias instability is reduced from 0.335 and 0.227 deg/h(fast and slow axes output, respectively) to 0.061 deg/h.

Quadrature demodulation with synchronous difference for interferometric fiber-optic gyroscopes

“…The polarization maintaining IFOG is one of the typical IFOG structures meeting the requirement of reciprocity [3,20,21]. Figure 1 shows the open-loop polarization maintaining IFOG used in our experiment, and implementation details of modulation and demodulation.…”

“…By substituting φ I and φ Q for φ s in Eq. (21) in Appendix respectively, we get two detection results of the rotation rate with different signs as Ω I = −Ω, and Ω Q = Ω. As shown by Eq.…”

“…(9), where signals are in their ideal forms. In practice, detected results have error terms induced by noise, which are changing over time [10,21] …”

A numerical algorithm to determine straightness error, surface roughness, and waviness measured using a fiber optic interferometer

“…This enables fiber optic interferometry to be used in various applications in medicine [3,12,[18][19][20] and industry [21][22][23]. Fiber optics have the advantage of low loss, safety, low cost, accessibility to small places due to their small size [24].…”

“…As the distance between the target and the sensing fiber changes due to the movement of the target or the probe, an optical path difference between the laser beam internally reflected from air/glass interface in the fiber and the laser beam reflected from the target develops, resulting in interference between these two beams. The resulting intensity [19][20][21][22][23][24][25][26][27][28][29] detected by the photo-detector is given as [26]: Phase difference can be expressed as a function of optical path difference as:…”