Abstract: A light source signal is amplitude modulated by a phase modulated sinusoid and passes through two directional couplers so that two beams are formed. The beams are transmitted to the ends of an optic-fiber coil for propagation therethrough in opposite circular directions. An optical phase modulator is present at one end of the coil so that a phase modulation of fixed frequency and amplitude is introduced to a first beam as it enters the coil and to the counterpropagating beam as it leaves the coil. The counterpropagating beams produce a signal at a photodetector which is a function of rotation rate. An electronic control unit is connected to the photodetector to generate a digital signal output as a frequency which is a measure of rotation rate. A feedback loop is completed by connecting a signal, produced by the control unit, to the amplitude modulated light source for nulling the phase shift due to rotation rate.

Abstract: A magnetic resonance gyroscope has auxiliary coils mounted adjacent the coils which normally produce the DC H.sub.o field for the gyro spin generators. The auxiliary coils establish an inhomogeneous H.sub.o field which results in a reduction of the rate bias shifts due to readout lamp plasma shifts. Alternately, rate bias shifts may be reduced by introducing a temperature differential between the two absorption cells employed in the gyro.

Abstract: A magnetic resonance gyroscope wherein the pump lamp includes an isotopic mixture of Hg, which controls the optical spectra of the pump beam to eliminate .sup.201 Hg alignment moments and to reduce light-induced frequency shifts. The inclusion of quarter-wavelength plates, reflection polarizers, and adjustable magnetic fields acting on the pump and readout lamps permit fine tuning control over the respective spectra to further enhance the rate bias stability of the gyroscope.

Abstract: In order to provide an all-angle gradient magnetometer, first and second magnetic resonance cells are mounted to a common base and separated by a predetermined distance. Circularly polarized pumping light is passed through the two cells orthogonally. Mixed with the circularly polarized pumping light is readout light which is linearly polarized. At the output of the cells appropriate filters are provided to filter out the pumping light whereafter the modulated readout light is detected in push-pull manner and fed back to modulate the pumping beams and at the same time fed to signal processing means to permit detecting phase differences between the outputs of the separated cells.

Abstract: An optically pumped magnetic resonance gyroscope wherein the direction of the magnetic fields intersecting the absorption cells of two interconnected spin generators may be oriented in the same or opposite directions, but are of unequal magnitude. The output from each spin generator comprises signals having frequencies characteristic of the two isotopes contained in the cell of each spin generator. These signals are applied to filter circuits each of which passes a desired frequency. Two signals are multiplied in frequency. A pair of phase difference sensors measure differences in phase between pairs of filter outputs, and controls the spin generators in such a manner as to return a first function of the phase differences to null. The output signal from the instrument, derived from a second function of the phase differences, represents the angular rotation of the gyro about a predetermined axis.

Abstract: A method and apparatus for making measurements of an electrically conductive material, which measurements can be used to determine the separate parameters thickness and conductivity without knowledge of the value of either of these parameters and in a manner giving improved freedom from sheet flutter, in which a transmitter coil is placed on one side of the sheet of material to be measured and a receiver coil on the other side at fixed distance from the transmitter coil and the transmitter coil is operated at two separate frequencies to obtain two relative phase relationships between the current in the transmitter coil and the electromotive force in the receiver coil such that the resulting phases differ in their functional relationships to thickness and conductivity, the frequency and phase being measured to obtain values which then can be used in independent equations to solve for at least one of thickness and conductivity.