Abstract: A helium magnetometer includes a helium cell containing helium, preferable .sup.4 He. A solid state laser strikes the helium cell at one end with a laser having a wave length of 1082.91 nm in the embodiment of a .sup.4 He cell. The helium atoms precess at known frequencies for different magnetic fields. The transparency of the helium cell at 1082.91 nm with .sup.4 He is a function of the resonance of the atoms within the helium cell. A radiation detector positioned on a second end of the helium cell opposite the end where the laser strikes detects the laser when transmitted through the helium cell and produces an electrical signal in response to the transmitted laser. The resonance of the helium cell is enhanced by a Voltage Controlled Oscillator, VCO, which provides a variable output frequency to a pair of coils positioned on the sides of the helium cell and electrically connected to the VCO to receive the variable output frequency.

Abstract: In a multi-slice magnetic resonance imaging system which employs a train of plural RF NMR nutation pulses, the frequency spectrum and/or magnetic gradient employed for succesive pulses is controlled so as to effect more nearly equal full-width-half-magnitude (FWHM) or other spatial dimensions of actual nuclei nutation variation versus distance curves for all of the slice selective nutation pulses. The result is a reduction of any "gap" of non-imaged volume disposed between the succession of selected MRI slice volumes.

Abstract: A polarized internal target apparatus with a polarized gas target of improved polarization and density achieved by mixing target gas atoms with a small amount of alkali metal gas atoms, and passing a high intensity polarized light source into the mixture to cause the alkali metal gas atoms to become polarized which interact in spin exchange collisions with target gas atoms yielding polarized target gas atoms.

Abstract: A system for measuring the earth's magnetic field includes a magnetometer and apparatus for maintaining a predetermined magnetometer tilt in the magnetic meridional plane regardless of changes in vehicle heading. The magnetometer is of the type whose optimum measurement sensitivity is defined by a cone of predetermined angle that is symmetric about its optical axis. It is engaged to a planar platform by gimbal apparatus forming orthogonal axes of rotation that cooperates with a rotatable hemispherical strip to allow the magnetometer to be continuously repointed during changes in the heading of a carrier vehicle so that it is maintained in the magnetic meridional plane at a predetermined tilt angle.

Abstract: An apparatus for measuring the magnitude of a magnetic field in one embodiment includes a .sup.3 He cell having an oscillator connected thereto for producing an electrical discharge for metastable .sup.3 He atoms, a .sup.4 He lamp having an oscillator connected thereto for producing .sup.4 He radiation and an optical path to the .sup.3 He cell including a lens for collimating the .sup.4 He radiation and a circular polarizer. The imaged .sup.3 He atoms and .sup.4 He radiation interact to magnetize a portion of the .sup.3 He atoms in a direction parallel to the direction of the ambient magnetic field. After the cell magnetization, an oscillatory magnetic field normal to the ambient field is established by coils connected to a frequency synthesizer which is scanned over a frequency interval including the free precession (Larmor) frequency. This action rotates the direction of magnetization of the .sup.

Abstract: A nuclear magnetic resonance gyroscope which derives angular rotation thef from the phases of precessing nuclear moments utilizes a single-resonance cell situated in the center of a uniform DC magnetic field. The field is generated by current flow through a circular array of coils between parallel plates. It also utilizes a pump and readout beam and associated electronics for signal processing and control. Encapsulated in the cell for sensing rotation are odd isotopes of Mercury Hg.sup.199 and Hg.sup.201. Unpolarized intensity modulated light from a pump lamp is directed by lenses to a linear polarizer, quarter wave plate combination producing circularly polarized light. The circularly polarized light is reflected by a mirror to the cell transverse to the field for optical pumping of the isotopes. Unpolarized light from a readout lamp is directed by lenses to another linear polarizer.

Abstract: A method and apparatus for optical pumping of an NMR cell by means of laser light. A current driver provides an a.c. current waveform as injection current to a laser diode. The resulting laser intensity spectrum closely approximates the absorption spectrum of the cell to thereby increase the signal generated for a given power input.

Abstract: A nuclear magnetic resonance gyroscope which derives angular rotation thef from the phases of precessing nuclear moments utilizes a single-resonance cell situated in the center of a uniform DC magnetic field. The field is generated by current flow through a circular array of coils between parallel plates. It also utilizes a pump and read-out beam and associated electronics for signal processing and control. Encapsulated in the cell for sensing rotation are odd isotopes of Mercury Hg.sup.199 and Hg.sup.201. Unpolarized intensity modulated light from a pump lamp is directed by lenses to a linear polarizer, quarter wave plate combination producing circularly polarized light. The circularly polarized light is reflected by a mirror to the cell transverse to the field for optical pumping of the isotopes. Unpolarized light from a readout lamp is directed by lenses to another linear polarizer.

Abstract: An optical-physics package used in an atomic frequency standard is miniaturized and the performance thereof improved. The optical-physics package includes a microwave cavity in which is positioned a filter cell and an absorption cell, preferably located in close physical proximity to one another. The microwave cavity may double as an oven, and is preferably designed to operate in the TE111 mode with "E" probe microwave coupling. Dielectric loading is provided by the filter cell and absorption cell to reduce the internal dimensions of the microwave cavity.

Abstract: There is disclosed a magnetic alignment device and method for its fabrication in which the aligned magnetic moments of a gas enclosed within a container have an increased relaxation time, hence an increase signal to noise output.One embodiment is a nuclear magnetic resonance gyroscope including a container for gas having a layer of rubidium hydride on its inner surface. Enclosed within the container is rubidium vapor and xenon-131 gas.The layer of rubidium hydride is manufactured by reacting hydrogen gas and rubidium at a temperature between approximately 70.degree. and about 250.degree. C. In one specific method, a layer of rubidium hydride is formed by heating rubidium and hydrogen gas at about 85.degree. for about 7 days.

Abstract: There is disclosed a nuclear magnetic alignment device for use in a nuclear magnetic resonance gyroscope and the like. One embodiment includes a container for gas having a layer of rubidium hydride on its inner surface. The container comprising a spherical portion and a tip portion, is rotationally symmetric about an axis of symmetry. Enclosed within the container is a nuclear moment gas having a nuclear electric quadrupole moment, such as xenon-131, and an optically pumpable substance, such as rubidium. A portion of the rubidium is a vapor. The remainder is a condensed pellet which is deposited in the tip of the container such that the pellet is also rotationally symmetric about the axis of symmetry of the container. A layer of rubidium hydride is deposited on the inner surface of the container.

Abstract: A nuclear magnetic resonance gyro using two nuclear magnetic resonance gases, preferably xenon 129 and xenon 131, together with two alkaline metal vapors, preferably rubidium, potassium or cesium, one of the two alkaline metal vapors being pumped by light which has the wavelength of that alkaline metal vapor, and the other alkaline vapor being illuminated by light which has the wavelength of that other alkaline vapor.

Abstract: A signal processor which involves separation of the cell signals from a magnetic resonance gyro (MRG) using phase locked loops that also serve as frequency multipliers, phase shifting one cell output to maintain phase comparisons within the monotonic region of the phase detectors, PDM/Digital conversion of the MRG signals and finally microcomputer processing to obtain gyro angle to the required resolution and update 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: Apparatus for determining the composition of mercury-cadmium-telluride or other alloy semiconductors by using a four-photon mixing phenomenon. Means are provided for a pair of colinear laser beams of different optical frequencies such that the colinear beams passed through a sample of Hg.sub.1-x Cd.sub.x Te or other alloy semiconductors to produce emissions beams of the original incident optical frequencies and two or more additional optical frequencies formed by an electron spin-flip interaction. A magnetic field means is employed for varying a magnetic field across the sample during passage of the colinear beam from the points substantially below to substantially above the resonant field of the sample to produce a spin-flip signal which has a peak amplitude. Detector means are adapted to receive the emission beams to identify the spin-flip signal peak from which the spin-level splitting factor can be measured. Upon measurement of the spin-level splitting factor, the value for x can be calculated in Hg.sub.

Abstract: A method for line narrowing in nuclear magnetic resonance (NMR) studies in solids is described. The method employs quasi-continuous amplitude modulation of an rf field wherein the field is eliminated at intervals for short periods of time at or about the time when the amplitude for both the maximum and minimum approach zero, these intervals creating windows where the NMR signal can be observed.

Abstract: Disclosure is made of a magnetic field gradient measuring device comprising two sensors arranged at points of a magnetic field which are to be investigated, and connected with their outputs to inputs of a phase detector. Each of the two sensors comprises an absorption cell filled with atoms of a working matter. Arranged at the input of said absorption cell is a light source intended for optical pumping of atoms of the working matter. At the output of said absorption cell there is arranged a photocell intended to register the beam of light passing through the cell. The cell itself is located inside a radio frequency coil energized with current of a variable frequency close to the magnetic transition resonance frequency of atoms of the working matter, which is determined by the magnetic field intensity at the sensor location. The coils are energized by a means common for both sensors.