42 results about "Larmor precession" patented technology

The invention discloses a rubidium atomic magnetometer and a magnetic field measuring method. Based on the principle of nonlinear magneto-optic rotation, and through combination of timing control and tracking type frequency locking control, the atomic magnetometer achieves a large dynamic measurement range, high magnetic field sampling rate and high sensitivity. A DSP timing control module controls on-off of an acousto-optic modulator and a radio-frequency signal source in the physical part of the rubidium atomic magnetometer according to timing combination to adjust the magnetic field sampling rate N. The DSP timing control module further controls acquisition triggering of a data acquisition card. A calculation unit gets the Larmor precession frequency (f) through fast Fourier transform with use of a received rubidium atom Larmor precession free relaxation signal, and further calculates the value of an external magnetic field. The calculation unit selects a high magnetic field sampling rate module or a low magnetic field sampling rate module before measurement according to the pre-judged dynamic range of a to-be-measured magnetic field, and sets whether a tracking type frequency locking work mode is used when the low magnetic field sampling rate module is selected. In the working process, data is acquired and processed, and the value of the magnetic field is output.

The invention relates to an atomic spin procession detecting method and an atomic spin precession detecting device based on electro-optic modulation. Alkali metal atoms in a spin-exchange relaxation free state are used for sensing an external magnetic field or angular rate, thereby generating atomic spin Larmor precession. An electro-optic modulator is used for performing electro-optic modulation on detected laser. Through output light strength detection by the electro-optic modulator and demodulation of a phase-locked amplifier, output light strength and frequency doubling signal strength are obtained. Finally a signal acquisition and processing circuit measures an atomic spin precession signal, and furthermore measurement to the external magnetic field or inertia can be realized. According to the atomic spin procession detecting method and the atomic spin procession detecting device, advantages such as simple modulation, small size, high sensitivity, low temperature effect and simple operation condition in the electro-optic modulator are exerted. The atomic spin procession detecting method and the atomic spin procession detecting device have relatively high sensitivity and relatively high stability. The novel atomic spin procession detecting method is based on an atomic spin effect and can be used for industrial integration and practical application of atomic spin sensing devices in future.

The invention relates to an aeromagnetic field vector detecting device and a detecting method, a DFB laser which has the same lasing frequency with an alkali metal atom D1 wire is adopted as a pump light source, the light emitted by the DFB laser generates circular polarization pump light polarized alkali metal atoms with free adjustable laser power through an optical isolator, an optical attenuator, a polarizer and a lambda/4 wave plate, and the atom is made to have macroscopic magnetic moment. A detected weak magnetic field in a y axis direction makes the magnetic moment to generate Larmor precession on an xoz plane around the y axis. The polarization plane rotation of the linearly polarized light caused by circular dichroism of a polarized atom, the pump light is removed, the deflection angle gradually vibrates and attenuates to zero, a zero-cross detection device is adopted to detect the time difference between the time of removing the pump light and the first zero crossing point, the Larmor prescession frequency can be obtained, and a magnetic-field vector value is obtained by dividing the Larmor prescession frequency by a gyromagnetic ratio. According to the invention, the device and the method have the advantages of high magnetic-field vector detection precision, fast response frequency and good repeatability, and are suitable for aeromagnetic field vector detecting mobile platform magnetic measurement.

The invention relates to a magnetic signal enhancing device for a low-field nuclear magnetic resonance imaging instrument and a making method thereof and solves the problem that low-field magnetic resonance imaging equipment is low in image signal-to-noise ratio and space resolution rate when compared with the prior art. An artificial electromagnetic structure resonance unit comprises a metal square spiral line etched on the upper surface of a substrate, a metalized via hole is formed in each of two ends of the metal square spiral line and penetrates the substrate, a metal microstrip line is printed on the lower surface of the substrate and connected with the metalized via holes, and a non-magnetic patch capacitor is welded on the metal microstrip line. The artificial electromagnetic structure resonance unit formed by connecting the metal square spiral line on the front of the substrate with a microstrip loaded with the non-magnetic patch capacitor on the back of the substrate throughthe metalized via hole has negative magnetic conductivity at low-field magnetic resonance Larmor precession frequency, and the artificial electromagnetic structure resonance unit can effectively enhance magnetic resonance radio frequency field magnetic signals by utilizing the negative magnetic conductivity.

The invention discloses an integrated measurement method of a constant and a non-orthogonal angle of a three-axis coil, and belongs to the technical field of optical detection, and magnetic field detection and analysis. Based on a problem that the precision of magnetic fields generated by the three-axis coil directly affect the sensitivity of an ultrahigh sensitivity magnetic field/inertia measurement device based on the non-spin exchange theory, the invention provides the integrated measurement method of the constant and the non-orthogonal angle of three-axis coil based the atomic spin Larmor precession theory. The provided method fills a gap of lack of a rapid and efficient integrated measurement method of the constant and the non-orthogonal angle of a three-axis coil, and provides preconditions and guarantee for the sensitivity of atom magnetometers.

The invention discloses a novel radio frequency atom magnetometer and an implementation method thereof. According to the invention, the method comprises the steps: enabling the laser wavelength to bestable, and keeping resonance between the laser wavelength and the alkali metal atom ground state energy level; enabling a polaroid to be perpendicular to the direction of the laser beam to change laser into linearly polarized laser; enabling the linearly polarized laser to pass through the atomic gas chamber and to be received by the photoelectric detector, wherein the direction of the linearly polarized laser is parallel or vertical to the direction of the to-be-measured alternating magnetic field; enabling the static magnetic field to be stable and unchanged, wherein the direction is parallel to the linear polarization laser direction, and the radio frequency field direction is perpendicular to the to-be-measured alternating magnetic field direction; enabling the photoelectric detectorto detect the light intensity value change of all the linearly polarized lasers passing through the atomic gas chamber and outputting a voltage value, collecting the voltage value through the feedbackcontroller, and performing feedback control on the signal generator, so that the absolute value of the difference between the radio frequency field frequency and the to-be-measured alternating magnetic field frequency is equal to the Larmor precession frequency of alkali metal atoms; and calculating the frequency and the magnetic induction intensity of the to-be-measured alternating magnetic field according to the magnetic resonance spectrum. The method has the advantages of simple operation and large measurement range.

The invention discloses a current metering device and method based on quantum natural references. The current metering device comprises a to-be-measured magnetic field generation assembly, a pumping-detection type atom magnetometer 3 and a quantum current measurement assembly. The to-be-measured magnetic field generation assembly comprises a magnetic shielding cylinder 1, a standard coil 2 and a current source 8. The magnetic shielding cylinder 1 is used for shielding a geomagnetic field, the standard coil 2 is arranged in the magnetic shielding cylinder 1 in an axial symmetry mode, and the current source 8 inputs a current to the standard coil 2 to generate a to-be-measured magnetic field. A probe part of the pumping-detection type atom magnetometer 3 is arranged at the geometric center of the standard coil 2 and is used for measuring a uniform magnetic field on the axis of the standard coil 2. The quantum current measurement assembly comprises a standard resistor 4 calibrated by a quantum resistance reference and a standard voltmeter 5 calibrated by a quantum voltage reference. Based on the principle that a magnetic field value measured by the pumping-detection type atom magnetometer 3 and a current value in the standard coil 2 are in a linear relation, metering of a current in a wide measuring range from microampere (10 <-6 > A) to ampere (A) is achieved. The coil coefficient of the standard coil 2 is traced to three quantum natural references including Josephson effect (voltage), quantum Hall effect (resistance) and Larmor precession effect (magnetic induction intensity).

The invention relates to a rubidium atomic magnetometer, belonging to the technical field of atomic magnetometers. The rubidium atomic magnetometer is designed based on a magneto-optic resonance technology. According to the rubidium atomic magnetometer, rubidium atoms are highly polarized by utilizing pumping laser generated by a pumping laser device, the rubidium atoms are driven to conduct Larmor precession by means of interaction between the polarized rubidium atoms and detection laser generated by a detection laser device, and a precession frequency is obtained according to subsequent analysis and processing of a detected signal; and absolute measurement of a space weak magnetic environment is realized by combining a relationship between the magneto-optic resonant frequency and an external magnetic field. The rubidium atomic magnetometer has the advantages of high sensitivity, low energy consumption, low cost, small size and the like, has broad application prospect in aspects of space physics and geophysics, deep space magnetic field detection, military anti-submarine, biomedicine and the like, and is of important research value.

The invention provides a laser heating nuclear magnetic resonance gyroscope, which consists of: a quartz vacuum chamber, an atomic gas chamber, a 3D orthogonal coil, a heating laser light source, an optical fiber temperature measurement module, a pumping laser light source, a detection laser light source, a balance photoelectric amplifier, and a lock-in amplifier. Specifically, the lock-in amplifier analyzes the amplified detection optical signal output by the balance photoelectric amplifier and a reference drive signal of the 3D orthogonal coil to obtain the reference drive signal's frequencycomponent information of the 3D orthogonal coil in the balance photoelectric amplifier, and the frequency component information is sent a programmable logic controller; the programmable logic controller controls the power of the heating laser light source according to the surface temperature of the atomic gas chamber, and resolves the larmor precession frequency information of the nuclear magnetic resonance gyroscope according to the frequency component information. The laser heating nuclear magnetic resonance gyroscope provided by the invention can thoroughly eliminate complementary magneticfield interference caused by electrical heating and resistance temperature measurement, and can effectively improve the detection precision and sensitivity of the nuclear magnetic resonance gyroscope.

The invention discloses an atomic magnetometer probe based on an optical virtual magnetic field technology, which relates to the technical field of atomic magnetometers, and aims to solve the problemsthat the existing atomic magnetometer is low in signal-to-noise ratio and cannot perform high-sensitivity measurement on a magnetic field. The atomic magnetometer probe comprises a laser, a 1/2 waveplate, a polarization beam splitter prism, a 1/4 wave plate, an atomic gas chamber, a photoelectric detector, a semi-transparent and semi-reflective mirror, a frequency discrimination module and a PIDfeedback circuit. The atomic magnetometer probe utilizes laser to control atoms to extract magnetic field information sensed by the atoms, namely, utilizes the relationship between the spin of unpaired electrons or helium atom electrons on the outer layer of gaseous alkali metal cesium atoms and a magnetic field, controls the electron energy level transition in the atoms through an optical method, and realizes the frequency measurement of atomic Larmor precession, and thus, high-sensitivity measurement of the atomic magnetometer on the magnetic field is realized. The atomic magnetometer probeis suitable for the detection field.

The invention provides a system and method for increasing the signal-to-noise ratio of a Larmor precession signal of an Overhauser magnetic sensor. The system comprises the Overhauser magnetic sensor,a sensor excitation unit, an FID signal processing unit and a power supply battery, wherein a signal excitation end of the Overhauser magnetic sensor is connected with a radio frequency excitation signal in the sensor excitation unit, a signal receiving end of the Overhauser magnetic sensor is connected to a direct-current pulse excitation end and the FID signal processing unit through a single-pole double-throw switch, and a signal connection path of the Overhauser magnetic sensor is selected by controlling the single-pole double-throw switch. According to the method, an LC resonance and narrow-band filter is utilized firstly to limit the frequency band of the Larmor signal, primary noise reduction is performed, a time-frequency peak filtering algorithm is used for performing secondary noise reduction and signal reconstruction on the Larmor signal, random noise and noise introduced by a conditioning circuit can be further suppressed, and the signal-to-noise ratio of the Larmor signalis substantially increased.

The invention relates to a magnetic field measuring device which comprises a laser detection module comprising a laser, a detector and a control module, and a magnetic induction module comprising an atomic gas chamber and a reflector. The magnetic induction module is arranged in a magnetic field to be measured, and a first optical signal with the frequency consistent with the transition frequency of atoms is input into the atomic gas chamber through the laser to polarize the atoms, so that the atoms in the atom air chamber perform Larmor precession under the action of the magnetic field to be measured; the control module performs amplitude modulation on the first optical signal, so that the modulated first optical signal is input into the atomic gas chamber and then returns to the atomic gas chamber through the reflective mirror to form a second optical signal, and the detector acquires a light intensity signal of the second optical signal and sends the light intensity signal to the control module; the control module determines the magnetic field intensity of the magnetic field to be measured according to the light intensity signal and the gyromagnetic ratio of the atoms. Electrical noise interference of the detector on atoms in the atomic gas chamber can be avoided, the sensitivity of the magnetic induction module is improved, and the temperature of the atomic gas chamber is reduced.

The invention discloses a non-invasive remote substance detection device based on ground and ball field nuclear magnetic resonance, which is based on a nuclear magnetic resonance technology principle, that is, by utilizing Zeeman energy level splitting and Larmor precession of a substance magnetic atomic nucleus induced by an earth magnetic field, a detection area is irradiated by extremely-low-frequency electromagnetic excitation pulses; a specific magnetic atomic nucleus absorbs photon energy carried by a specific radio frequency and jumps from a low energy level to a high energy level to generate a nuclear magnetic resonance signal; and a nuclear magnetic resonance signal is detected and sensed by virtue of a signal receiving device, so that qualitative and spatial positioning of a detected target substance is realized. The device has a clear scientific basis and a clear technical implementation approach, is not restricted by the type and physical form of a detected substance in the detection process, and does not change the physical and chemical properties of the detected substance, so that the device is a non-invasive remote substance detection device; and the device not only can be applied to underground mineral resource exploration, but also can be applied to related fields such as environmental protection and archaeological.

The invention belongs to the technical field of atomic measurement, and discloses a spin noise spectrum-based calibration device for measuring a weak field by a Hall magnetometer, which comprises a detection light source, wherein first detection light output by the detection light source passes through a first half-wave plate, a first polarizer and a lens, then enters an atomic gas chamber along an X direction, passes through a second half-wave plate, a first Wollaston prism, and then is detected by a first balance detector; the atomic gas chamber is arranged in a magnetic shielding cylinder, and a first Helmholtz coil used for providing a magnetic field in the Y direction is arranged in the magnetic shielding cylinder; the output end of the first balance detector is connected with a first fast Fourier transform dynamic signal analyzer. And the first fast Fourier transform dynamic signal analyzer is used for analyzing the detection signal to obtain a corresponding Larmor precession frequency. The device can realize calibration of the Hall magnetometer and can be widely applied to the field of magnetometer calibration.

The invention discloses a magnetic field gradient measurement method and an atomic magnetic gradiometer system. The method comprises the steps of controlling a light modulator to process laser, and obtaining pump light and probe light, controlling a light modulator to periodically modulate the pump light to obtain modulated pump light with a modulation signal, controlling the signal detector to receive second change detection light obtained after the detection light sequentially passes through the Larmor advance action of the first polarization state atom and the Larmor advance action of the second polarization state atom, and acquiring a polarization rotation angle signal of the second change detection light, demodulating a polarization rotation angle signal of the first change detection light, calculating to obtain the value of a first external magnetic field to be measured according to the frequency of the modulation signal, and acquiring the magnetic field intensity at the first polarization state atom at the same time. The sensitive and compact method for simultaneously measuring the magnetic field intensity and the magnetic field gradient is realized, common-mode noise in magnetic field gradient measurement can be inhibited, and the sensitivity and the precision of magnetic field gradient measurement are improved.