A magnetoencephalograph M1 includes: multiple pump-probe type optically pumped magnetometers 1A; a bias magnetic field forming coil 15 for applying a bias magnetic field in the same direction as a direction of pump light of each of the multiple pump-probe type optically pumped magnetometers 1A and in a direction approximately parallel to a scalp; a control device 5 that determines a current for the bias magnetic field forming coil and outputs a control signal corresponding to the determined current; and a coil power supply 6 that outputs a current to the bias magnetic field forming coil in response to the control signal output from the control device.

A structure for magnetic flux sensor conditioning is presented which partitions an input analog signal of unknown integrity into two: susceptible and insusceptible. The structure scrutinizes the susceptible signal partition, in view of additional guard sensor information, through a mixed-signal processing side-chain that employs a non-invasive physical magnetic attack detection algorithm. The side-chain either validates, or replaces with a best estimate, the susceptible signal partition, depending upon the absence or presence of attack, respectively. The structure finally recombines the scrutinized susceptible signal partition with the insusceptible signal partition. The result is an analog magnetic flux sensor signal that is robust against skillful, surreptitious, spoofing attacks. If unmitigated, such attacks may induce catastrophic consequences into systems relying upon the magnetic flux sensor.

Various embodiments comprise a laser bonded glass-silicon vapor cell for performing spectroscopy on particles like atoms or molecules. In some examples, the laser bonded glass-silicon vapor cell comprises a glass base, a glass top, a silicon piece, and a filling material. The silicon piece comprises at least one through hole. The lower surface of the silicon piece is hermetically bonded to the glass base. The upper surface of the silicon piece is laser bonded to the glass top. The filling material is positioned in a cavity formed by the through hole, the glass base, and the glass top. The filling material may comprise an alkali metal, a salt slush, an inert gas, or a vacuum encapsulation.

Various embodiments comprise a laser bonded glass-silicon vapor cell for performing spectroscopy on particles like atoms or molecules. In some examples, the laser bonded glass-silicon vapor cell comprises a glass base, a glass top, a silicon piece, and a filling material. The silicon piece comprises at least one through hole. The lower surface of the silicon piece is hermetically bonded to the glass base. The upper surface of the silicon piece is laser bonded to the glass top. The filling material is positioned in a cavity formed by the through hole, the glass base, and the glass top. The filling material may comprise an alkali metal, a salt slush, an inert gas, or a vacuum encapsulation.

Systems and methods are provided that facilitate high-sensitivity, carrier-resolved photo-Hall effect measurements. Majority and minority carrier properties can be measured and determined simultaneously. In one aspect, a system and method determine majority carrier type, density and mobility and, with modulated illumination, minority carrier mobility and photocarrier density. In another aspect, a system and method can determine hole and electron mobility, photocarrier density, absorbed photon density, recombination lifetime and diffusion length for hole, electron and ambipolar transport.

A magnetometer that finds a magnitude of an ambient magnetic field, comprising: a) a diamond cubic structure crystal, with an ensemble of paramagnetic defects oriented along each of the crystal's four tetrahedral axes; b) a microwave source that produces a microwave field at the crystal, of controllable frequency over a range that includes microwave resonance frequencies of paramagnetic defects oriented along all four axes; c) a light source that illuminates the paramagnetic defects with light that causes fluorescent emission from the paramagnetic defects; d) a light detector that measures the fluorescent emission; and e) a controller configured to: 1) measure the fluorescent emission at different microwave frequencies within the range, to obtain a spectrum of the paramagnetic defect ensemble; 2) calculate a variance property of the spectrum; and 3) calculate the magnitude of the ambient magnetic field from the variance property.

An optical fiber distributed sensing system may include an optical fiber for distributed sensing. The optical fiber may include a core including glass and diamond particles with nitrogen-vacancy (NV) centers distributed within the glass. The optical fiber may also include at least one glass layer surrounding the core. An optical source may be coupled to the optical fiber and operable from an end thereof. An optical detector may be coupled to the optical fiber to detect fluorescence therefrom.

An optical fiber distributed sensing system may include an optical fiber for distributed sensing. The optical fiber may include a core including glass and diamond particles with nitrogen-vacancy (NV) centers distributed within the glass. The optical fiber may also include at least one glass layer surrounding the core. An optical source may be coupled to the optical fiber and operable from an end thereof. An optical detector may be coupled to the optical fiber to detect fluorescence therefrom.

The present disclosure discloses a system and method for testing the spatial distribution uniformity of an alkali metal atom number density of an atom magnetometer. The system includes a detection laser, a laser beam expanding system, a polarizing element, a magnetic shielding system, an alkali metal atom gas chamber, a beam profile camera, a beam splitting prism, etc., which are sequentially arranged in a light advancing direction. In the method, based on an optical absorption principle, light intensity attenuations of linearly polarized light before and after passing through the alkali metal gas chamber are tested by using the beam profile camera with pixels in the level of um, a two-dimensional distribution matrix of an atom number density in space is calculated, and the distribution uniformity of the atom number density is analyzed by using a discrete coefficient.

The present disclosure discloses a system and method for testing the spatial distribution uniformity of an alkali metal atom number density of an atom magnetometer. The system includes a detection laser, a laser beam expanding system, a polarizing element, a magnetic shielding system, an alkali metal atom gas chamber, a beam profile camera, a beam splitting prism, etc., which are sequentially arranged in a light advancing direction. In the method, based on an optical absorption principle, light intensity attenuations of linearly polarized light before and after passing through the alkali metal gas chamber are tested by using the beam profile camera with pixels in the level of um, a two-dimensional distribution matrix of an atom number density in space is calculated, and the distribution uniformity of the atom number density is analyzed by using a discrete coefficient.