Gordon L. Mitchell

Dual Polarization Gyro

This paper presents a new fiber optic gyro configuration that is designed to provide independence from the principal bias errors due to the phase modulator. The configuration operates with optimum Π/2 phase shift for gyro sensitivity, 2x increase in scale factor and has been experimentally shown to provide a lOx improvement in immunity to modulator-induced bias errors.

Linearized fiber optic sensor readout

Interferometric sensors traditionally have been limited by their non-linear input-output characteristics. This paper presents a method for output linearization using four interferometer outputs corresponding to ±sin ct and ±coscp, where 4 is the relative phase of interferometer legs. These outputs are combined in an arctangent algorithm to extract (/). Applications to both Mach-Zehnder and Sagnac interferometers are discussed, with experimental data from a fiber gyro presented. The data taken over a 47r range of 4 demonstrate linearity and stability of the algorithm.

Fiber Optic Magnetometer Design

Magnetic sensors have been used in applications ranging from keyboard switches to submarine detection. Recently developed fiber optic magnetometers promise to provide high performance/moderate cost alternative to existing sensors. The special properties of fiber magnetometers such as directional response, high sensitivity, room temperature operation are discussed in the context of other magnetometers. Fiber magnetometer design considerations, fabrication procedures, and performance measurements using magnetostrictive alloy coatings are presented. Optimum performance is obtained with a 36% - 64% nickel-iron alloy electroplated over the polymer jacket on a single mode fiber. Sensor designs for fiber optic magnetometers are shown.

Numerical Modeling of Dual Polarization Interferometric Gyros and Sensors

In the research and development of fiber gyros there is a need for a capability to analyze and simulate the optical system. In order to predict performance, sensitivity, and the effect of changing parameters and imperfect components, some form of quantitative calculations would be very useful. Analytical methods quickly become intractable as the complexity of the system increases. For even the simplest fiber gyro configuration, for several optical paths, and for a few optical components, it is practically impossible to reduce a complete analytical description to a useful form. An accurate numerical simulation would be invaluable for low cost exploration of different designs, sensitivity calculations, and performance predictions.