What is fiber optic gyro

Fiber optic gyro concept

Fiber optic gyro is a very important angular rate sensor. It has the advantages of long life, fast start-up, high accuracy, low power consumption, wide dynamic range, etc. It plays an extremely critical role in the fields of aerospace, weapon navigation, etc.

At present, fiber optic gyros mainly use two schemes: interferometric fiber optic gyro (IFOG) and resonant fiber optic gyro (RFOG). Interferometric fiber optic gyros are relatively mature. In order to improve the detection accuracy of the system and reduce noise, a super-radiation light source (SLD) and a polarization-maintaining fiber coil of up to several hundred meters are used. At the same time, it also brings a large system weight and a stable system The shortcomings of reduced sex and higher cost.

The resonant fiber optic gyroscope uses the principle of multi-wave interference between circulating beams, which can obtain higher detection accuracy in shorter optical fibers, which requires a high-coherent light source Δυ <100 kHz, low-loss polarization-maintaining coupler, and high Coherent light sources also introduce strong backscattering noise.

After that, a reentrant fiber optic gyroscope (REFOG) was proposed. This type of gyroscope uses a low coherent light source (SLD), which uses the principle of outgoing interference after the light transmitted in the resonant cavity transmits the same number of turns. High output curve fineness, high detection sensitivity can be obtained by active amplification of the optical amplifier. The disadvantage is that the output contains a lot of light without rotation information (directly entering the resonator through the coupler), making it in a passive situation The lower detection sensitivity is lower. Even in the active case, the gain saturation also puts a burden on the optical amplifier. Moreover, the use of SLD is always a compromise in the gyro solution, but the device has the disadvantages of more complicated process technology, lower output power (generally <150 μW), expensive price, and poor light source stability, especially limiting the multi-axis system Improvement of system accuracy of medium light source reuse scheme.

Principle analysis of a new type of resonant interferometric fiber optic gyroscope