Optimization and Demonstration of a Fiber-Optic Gyroscope

Abstract: Fiber-optic gyroscopes play an important part in modern engineering. They are frequently used in transport systems, land surveying and in a wide variety of military applications to measure angular velocity. Consequently, it is of importance to be able to demonstrate the effects of such a component in a simple fashion for educational purposes. The goal of this bachelor thesis is to create an easy way to show the properties of a fiber-optic gyroscope. This will be done by creating a userfriendly visual display and an in-depth guide on how to operate and make calibrations for an existing gyroscope. It is important to note that the calibrations and optimizations are made for this particular apparatus and thus will not necessarily be applicable to similar constructions. The gyroscope itself uses a 1550 nm infrared laser beam that is split and coupled into opposite directions of a 14 km long coil of optical fiber. The beams are subsequently made to interfere and then measured. The measurement consists of a voltage signal that corresponds to the phase shift between the two beams. Thus rotating the gyroscope will change the voltage output which may then be translated to angular velocity. The tasks involved in this project will begin with finding the optimal signal. This is done by aligning the optical components using a visible HeNe laser with 632.8 nm wavelength. Then changing to the infrared laser and making careful adjustments to find the appropriate voltage output. Furthermore, the signal has to be transferred to a computer, which is done through an analog-to-digital converter. Once the signal can be detected, a visual interface can be created to show and use the voltage on the computer. The end result is a fiber-optic gyroscope with a useful display for demonstrations.